Agilent 355 Sulfur and 255 Nitrogen
Chemiluminescence Detectors
Operation and Maintenance
Manual
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Warnings
English
This symbol on the instrument indicates that the user should refer to the man-
ual for operating instructions.
WARNING
Any operation requiring access to the inside of the equipment, could result in
injury. To avoid potentially dangerous shock, disconnect from power supply
before opening the equipment.
WARNING
WARNING
WARNING
For continued protection against fire hazard replace fuse with same type and
rating.
This symbol indicates that to comply with European Union Directive
2002/96/EC for waste electrical and electronic equipment (WEEE), the Ana-
lyzer should be disposed of separately from standard waste.
This is a safety Class I product. It must be wired to a mains supply with a protective
earthing ground incorporated into the power cord. Any interruption of the protective
conductor, inside or outside the equipment, is likely to make the instrument dangerous.
Intentional interruption is prohibited.
WARNING
If this instrument is used in a manner not specified by Agilent, the protection provided by
the instrument may be impaired.
WARNING
WARNING
High voltage is present in the instrument when the power cord is connected, even if the
main power switch is in the standby mode. To avoid potentially dangerous shock, discon-
nect the power cord before removing the side panels.
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Ozone is a hazardous gas and a strong oxidant. Exposure to ozone should be minimized
by using the instrument in a well-ventilated area and by venting the exhaust of the vac-
uum pump to a fume hood. The ozone generator should be turned off when the instrument
is not in use.
WARNING
Burner temperature Is extremely hot. Do not touch. Allow to cool before servicing.
WARNING
WARNING
WARNING
Hydrogen is an extremely flammable gas. Use appropriate care when handling. Inspect
all connections with a suitable leak detector.
Oxygen rich environments can promote combustion and even result in spontaneous com-
bustion under conditions of high pressure and exposure to contamination. Use only oxy-
gen rated components and ensure that components are oxygen clean prior to use with
pure oxygen.
Exceeding the gas inlet pressure of 25 psig (1.72 bar) may damage the hydrogen and oxi-
dant sensors or burst their connective tubing.
WARNING
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Español
Cualquier operación que requiera acceso al interior del equipo, puede causar
una lesión. Para evitar peligros potenciales, desconectarlo de la alimentación
a red antes de abrir el equipo.
WARNING
WARNING
WARNING
WARNING
WARNING
Para protección contínua contra el peligro de fuego, sustituir el fusible por
uno del mismo tipo y características.
Este símbolo en el instrumento indica que el usuario debería referirse al man-
ual para instrucciones de funcionamiento.
Esto es un producto con clase I de seguridad. Debe conectarse a una red que disponga de
tierra protectora en el cable de red. Cualquier interrupción del conductor protector,
dentro o fuera del equipo, puede ser peligroso. Se prohibe la interrupción intencionada.
Si este instrumento se usa de una forma no especificada por Agilent, puede desactivarse
la protección suministrada por el instrumento.
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Français
Chaque opération à l'intérieur de l'appareil, peut causer du préjudice. Afin
d'éviter un shock qui pourrait être dangereux, disconnectez l'appareil du
réseau avant de l'ouvrir.
WARNING
WARNING
WARNING
WARNING
Afin de protéger l'appareil continuellement contre l'incendie, échangez le fus-
ible par un fusible du même type et valeur.
Le symbol indique que l'utilisateur doit consulter le manuel d'instructions.
Ceci est un produit de Classe de sécurité I. L'instrument doit être branché sur
l'alimentation secteur par un fil de secteur prévu d'une prise de masse. Chaque
interruption du conducteur protégeant, à l'intérieur ou á l'extérieur de l'appareil peut
rendre l'instrument dangereux. Interruption intentionnelle est interdite.
Si l'instrument n'est pas utilisé suivant les instructions de Agilent, les dispositions de
sécurité de l'appareil ne sont plus valables.
WARNING
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Deutsch
Vor dem Öffnen des Gerätes Netzstecker ziehen!
WARNING
WARNING
WARNING
WARNING
Für kontinuierlichen Schutz gegen Brandgefahr dürfen bei Sicherungswech-
sel nur Sicherungen der gleichen Stärke verwendet werden!
Dieses Symbol auf dem Gerät weist darauf hin, dass der Anwender zuerst das
entsprechende Kapitel in der Bedienungsanleitung lesen sollte.
Dies ist ein Gerät der Sicherheitsklasse I und darf nur mit einem Netzkabel mit
Schutzleiter betrieben werden. Jede Unterbrechung des Schutzleiters au erhalb oder
innerhalb des Gerätes kann das Gerät elektrisch gefährlich machen. Absichtliches
Unterbrechen des Schutzleiters ist ausdrücklich verboten.
Wenn das Gerät nicht wie durch die Firma Agilent, vorgeschrieben und im Handbuch
beschrieben betrieben wird, können die im Gerät eingebauten Schutzvorrichtungen
beeinträchtigt werden.
WARNING
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Italiano
Qualsiasi intervento debba essere effettuato sullo strumento può essere
potenzialmente pericoloso a causa della corrente elettrica. Il cavo di alimen-
tazione deve essere staccato dallo strumento prima della sua apertura.
WARNING
WARNING
WARNING
WARNING
Per la protezione da rischi da incendio in seguito a corto circuito, sostituire I
fusibili di protezione con quelli dello stesso tipo e caratteristiche.
Il simbolo sullo strumento avverte l'utilizzatore di consultare il Manuale di
Istruzioni alla sezione specifica.
Questo strumento è conforme alle specifiche per I prodotti in Classe I - Il cavo di
alimentazione dalla rete deve essere munito di "terra". Qualsiasi interruzione del cavo di
terra all'interno ed all'esterno dello strumento potrebbe risultare pericolòsa. Sono
proibite interruzioni intenzionali.
Se questo strumento viene utilizzato in maniera non conforme alle specifiche di Agilent,
le protezioni di cui esso è dotato potrebbero essere alterate.
WARNING
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Dutch
Iedere handeling binnenin het toestel kan beschadiging veroorzaken. Om ied-
ere mogelijk gevaarlijke shock te vermijden moet de aansluiting met het net
verbroken worden, vóór het openen van het toestel.
WARNING
WARNING
WARNING
WARNING
Voor een continue bescherming tegen brandgevaar, vervang de zekering door
een zekering van hetzelfde type en waarde.
Het symbool geeft aan dat de gebruiker de instructies in de handleiding moet
raadplegen.
Dit is een produkt van veiligheidsklasse I. Het toestel moet aangesloten worden op het
net via een geaard netsnoer. Bij onderbreking van de beschermende geleider, aan de
binnenzijde of aan de buitenzijde van het toestel, kan gebruik het toestel gevaarlijk
maken. Opzettelijke onderbreking is verboden.
Indien het toestel niet gebruikt wordt volgens de richtlijnen van Agilent, gelden de
veiligheidsvoorzieningen niet meer.
WARNING
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The following symbols are used on the equipment:
Caution - Refer to manual for
operating instructions
Caution - Risk of electrical
shock.
Caution - Hot surface.
Atención - Ver documentación Atención - Riesgo de sacudidas Atención - Superficie caliente.
pertinente.
eléctricas.
Attention - Consultez les
ocuments d'accomagnement. électrique.
Attention - Risque de choc
Attention - Surface brûlante.
Vorsicht - Heisse Oberfläche.
Pericolo - Superficie rovente.
Voorzichtig - Heet oppervlak.
Vorsicht - Siehe beiliegende
Unterlagen.
Vorsicht - Risiko eines
Elektroschocks.
Pericolo - Vedi
documentazione allegata.
Pericolo - Pericolo di scosse
elettriche.
Voorzichtig - Raadpleeg di
bijehorende documentatie.
Voorzichtig - Hoge spanning,
levensgevaar.
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Contents
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Overview 40
2
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Coking 73
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Agilent 355 Sulfur and 255 Nitrogen Chemiluminescence Detectors
Operation and Maintenance Manual
1
Introduction
This manual will guide you in the installation, operation, and troubleshooting
of the Agilent 355 Sulfur Chemiluminescence Detector (SCD) and the Agilent
255 Nitrogen Chemiluminescence Detector (NCD). This manual is intended for
use with the Agilent 355 SCD or 255 NCD with the Dual Plasma Burner and
Controller.
This operation and service manual has some important conventions, such as
the use of boxed warnings. This information is deliberately set out from the
text for emphasis and should be followed to assure operator safety and proper
instrumental operation.
If you are installing the 355 SCD or 255 NCD yourself, follow the installation
procedures described in the following sections. If your instrument is already
installed, turn to the Operation section to begin.
17
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Specifications
Technical Information — 355 SCD
Sensitivity*
Typical < 0.5 pg S/second (signal to noise 3.3:1)
g S/g C > 2 x 107
Typical Selectivity
Linearity
>104
Precision and Stability†
<2% RSD 2 hours
<5% RSD 72 hours
Ozone flow through the Post Ozone Restrictor
Typical reaction cell pressure
20-30 mL/min at 3-6 psig
4 - 8 Torr RV5 Oil Sealed Pump
6 - 12 Torr Dry Piston Pump
250-400 Torr operating
800 °C
Typical Burner Pressure
Typical Burner Temperature
Typical Air Flow Rate
65 SCCM recommended
3-10 SCCM recommended with FID adapter
40 SCCM recommended
0-1V, 0-10V
Typical Hydrogen Flow Rate
Signal Output Ranges
Typical time to reach 800 °C from room
temperature
10 min typical(120 VAC, 60 Hz)
Typical safety shroud outside temperature
Recorder output
<65 °C at 800 °C Burner temperature typical
0-1 V or 0-10 V
* Burner temperature 800 °C, 80 SCCM air, and 60 SCCM hyrdrogen, test compound dimethyl sulfide in toluene.
† Based on thiopene in benzene at 1 ppm mass sulfur, 1 µL injection split 1:10, 30 m, 0.32 mm ID, 1 µm thick CP
wax (n=10 for 2.5 hours; n=42 for 72 hours).
Subject to change without notice.
Technical Information — 255 NCD
Sensitivity
<3 pg N/second (signal to noise 3:1) in both N
and nitrosamine modes
Selectivity
Linearity
g N/g C > 2 to 107 in N mode (selectivity in
nitrosamine mode is matrix-dependent)
>104
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Repeatability*
<1.5% RSD 8 hours (~ the same in N and
nitrosamine)
<2% RSD 18 hours (~3% RSD in nitrosamine
mode over 21 hours)
Gas flow through Ozone Generator
Typical reaction cell pressure
20-30 mL/min at 3-6 psig (inlet pressure)
4 - 8 Torr RV5 Oil Sealed Pump
6 - 12 Torr Dry Piston Pump
130 - 150 torr operating
900 °C
Typical Burner Pressure
Typical Burner Temperature
Typical Hydrogen Flow Rate
Typical Oxygen Flow Rate
Signal Output Ranges
6-10 SCCM
8 - 15 SCCM
0-1V, 0-10V, 0 - 10V
* Burner temperature 950 °C, 11 SCCM oxygen, and 6 SCCM hydrogen; 25 ppm N as nitrobenzene in toluene;
0.2 µL injection on column (HP 19095-121Z), n=7 for 3 hours; n=13 for 18 hours and n=10
n-dipropylnitrosamine in toluene at 4 µg/mL, 0.2 µL injection on column (HP 19095-121Z).
Physical Specifications
Power requirements
355 SCD Detector
115 VAC, 50/60 Hz, 1400 W
100 VAC, 50/60 Hz, 1400 W
220-240 VAC, 50/60 Hz, 650W
255 NCD Detector
115 VAC, 50/60 Hz, 1400 W
100 VAC, 50/60 Hz, 1400 W
220-240 VAC, 50/60 Hz, 650W
Dual Plasma Controller
100-120 VAC, 50/60 Hz, 200 W
220-240 VAC, 50/60 Hz, 200 W
Dimensions and weight
Detector
Height: 16.0 in (40.6 cm)
Width: 9.2 in (23.4 cm)
Depth: 21.8 in (55.3 cm)
355 SCD Weight: 34.0 lbs (15.0 kg)
255 NCD Weight: 37.5 lbs (17.0 kg)
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Dual Plasma Controller
Height: 5.0 in (12.7 cm)
Width: 9.5 in (24.1 cm)
Depth: 12.5 in (31.8 cm)
Weight: 9.9 lbs (4.5 kg)
Dual Plasma Burner
Height: 12.3 in (31.2 cm)
Diameter: 4.0 in (10.2 cm)
Weight: 1.9 lbs (0.9 kg)
Oil Sealed Vacuum Pump (RV5)
Height: 10.3 in (26.1 cm)
Width: 6.0 in (15.2 cm)
Depth: 16.9 in (43.0 cm)
Weight: 47.3 lbs (21.5 kg)
or
Oil Free Dry Piston Pump
Height: 12.0 in (30 cm)
Width: 9.0 in (22.9 cm)
Depth: 14.0 in (35.6 cm)
Weight: 29.9 lbs (13.6 kg)
Installation Category
Pollution Degree
II
2
Ambient Temperature
Relative Humidity
50 - 104 °F (10-40 °C)
Up to 95%, noncondensing
Intended for indoor use only
2,000 m (6,562 ft)
Normal Operating Environment
Maximum Altitude
Mains Supply Voltage
Fluctuation not to exceed 10% of nominal
voltage
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Theory of Operation
Sulfur Chemiluminescence Detector
The Agilent model 355 Sulfur Chemiluminescence Detector (SCD) is a
sulfur-selective detector for gas chromatography. Operation of the SCD is
based on the chemiluminescence (light-producing reaction) from the reaction
of ozone with sulfur monoxide (SO) produced from combustion of the analyte:
Sulfur compound (analyte) → SO + H O + other products
2
SO + O → SO + O + hη (<300–400 nm)
3
2
2
A vacuum pump pulls the combustion products into a reaction cell at low
pressure, where excess ozone is added. Light produced from the subsequent
reaction is optically filtered and detected with a blue-sensitive photomultiplier
tube and the signal is amplified for display or output to a data system. Figure 1
is a pneumatic flow diagram that illustrates how the components of the system
are integrated.
The Detector has an enclosed, dedicated (Dual Plasma) Burner designed to
enhance production of the SO intermediate. This Dual Plasma Burner mounts
in the detector port of the GC. A Dual Plasma Controller provides temperature
control and gas-flow regulation to operate the Dual Plasma Burner.
The Agilent model 355 SCD provides high sensitivity (<0.5 pg S/sec), with
linear and equimolar response over four orders of magnitude (per Sulfur
atom) while maintaining high selectivity over common solvents. The Agilent
SCD is compatible with most commercially available gas chromatographs.
Nitrogen Chemiluminescence Detector
Operation of the Agilent model 255 Nitrogen Chemiluminescence Detector is
based on the chemiluminescence or light-producing reaction of ozone with
nitric oxide formed from combustion. Reacting nitric oxide with ozone results
in the formation of electronically excited nitrogen dioxide. The excited
nitrogen dioxide emits light, a chemiluminescence reaction, in the red and
infrared region of the spectrum. The light emitted is directly proportionally to
the amount of nitrogen in the sample,
NO + O NO NO + hη (>800 nm)
3
2
2
The light (hη) emitted by the chemical reaction is optically filtered and
detected by a photomultiplier tube. The signal from the photomultiplier tube is
amplified for display or output to a data system. Organic compounds
containing nitrogen react to form nitric oxide, carbon dioxide, and water.
H2/O2
---------------
R-N + O
→ NO + CO2 + H2O
2
Δ
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Dual Plasma Controller
The Dual Plasma Controller provides all operational parameters of the Dual
Plasma Burner except for the Detector base temperature. The Detector base
temperature is controlled by circuitry in the GC. Parameters monitored or
regulated by the Controller include Burner temperature, Burner temperature
set-point, hydrogen and oxidant flow rates, and Burner pressure. The
temperature set-point, actual pressure, oxidant and hydrogen flow rates are
displayed by rotation of a 4-position switch. Power, valve operation,
temperature within set-point range and fault conditions are indicated with
LED illumination on the front display panel.
The Dual Plasma Controller incorporates several safety features. The safety
circuitry detects faults such as power loss, vacuum loss, thermocouple failure,
heater element failure, broken ceramic tube, or high temperature. When a fault
is detected, the Fault LED illuminates and hydrogen and oxidant flow is
stopped by normally-closed solenoid valves.
Dual Plasma Burner with the 355 SCD
The Dual Plasma Burner is based on the same chemistry and basic principles
of earlier SCD Burner designs. A key difference, however, is the addition of a
second “flame” or “plasma,” the lower is oxygen-rich and the upper is
hydrogen-rich. The Burner consists of a tower assembly that contains an outer
sheath for burn protection, a heating element, thermocouple, and combustion
tubes. Conversion of sulfur containing compounds to SO occurs within the
ceramic reaction chamber housed in the Burner assembly. Agilent also
provides a Flame Ionization Detector (FID) option for the simultaneous
collection of hydrocarbon and sulfur chromatograms for some GCs.
Dual Plasma Burner with the 255 NCD
Compounds eluted from the GC column are combusted in the Dual Plasma
Burner first by an oxygen rich flame (plasma) followed by catalytic combustion
on a Noble metal screen. For hydrocarbons, this two stage combustion
technique results in complete conversion of the matrix to products, such as
carbon dioxide and water, which do not chemiluminesce with ozone. Nitrogen
atoms in a compound are converted into nitric oxide and potentially other
nitrogen oxide species. In the second stage, the catalyst is used to convert
other nitrogen oxide species to nitric oxide, resulting in a high efficiency of
conversion.
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Description of Major Components
Dual Plasma Burner
The Dual Plasma Burner consists of a tower assembly that contains an outer
sheath for burn protection, a heating element, thermocouple, and combustion
tubes. In the SCD, conversion of sulfur containing compounds to SO occurs
within the ceramic reaction chamber housed in the Burner assembly and
potentially interfering hydrocarbons are oxidized to CO and H O, with air as
2
2
the oxidant. In the NCD, oxygen is used as the oxidant.
A fitting is located on top of the Burner. The vacuum line from the Detector
box is connected directly to the top of this fitting and H2 is input to the longer
side of this fitting. The air inlet is connected to the base of the Burner.
The Burner is mounted onto the GC by a model-specific mounting kit (see
www.Agilent.com/chem or contact Agilent for the most current information).
The GC column is inserted into the Burner using a 1/32" knurled nut and fused
silica adapter ferrule.
A cross-section illustration of the Dual Plasma Burner for the 355 SCD is
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Figure 2 Cross-Section of the Dual Plasma Burner for the 255 NCD
Dual Plasma Controller
The Dual Plasma Controller powers the Dual Plasma Burner and supplies its
gases. Hydrogen and oxidant should be provided at 25 psig (1.72 bar) and the
Controller is plugged into an appropriate AC electrical outlet.
Exceeding the gas inlet pressure of 25 psig (1.72 bar) may damage the hydrogen and oxi-
dant sensors or burst their connective tubing.
WARNING
The parameters monitored or regulated by the Controller include Burner
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temperature, hydrogen and oxidant flow rates, and Burner pressure. The
temperature, actual pressure, oxidant and hydrogen flow rates are selected for
display by rotation of a 4-position control knob. Power, valve operation,
temperature within set-point range and fault conditions are indicated with
LED illumination on the front display panel.
The Dual Plasma Controller incorporates several safety features. The safety
circuitry detects faults such as power loss, vacuum loss, thermocouple failure,
heater element failure, broken ceramic tube, or high temperature. When a fault
is detected, the Fault LED illuminates and hydrogen and oxidant flow is
stopped by normally-closed solenoid valves.
Ozone Generator
The SCD and NCD produce ozone by corona discharge using a clean,
pressurized air or oxygen source. Use of oxygen should increase ozone
production and, hence, Detector response. High voltage to the ozone generator
is applied only when the reaction cell pressure is less than 100 torr in the SCD
and less than 200 torr in the NCD. Gas flow through the ozone generator is
controlled by a pressure regulator and flow restrictors.
Ozone is a hazardous gas and a strong oxidant. Exposure to ozone should be minimized by
using the instrument in a well ventilated area, changing the chemical trap regularly, and
venting the exhaust of the vacuum pump. The ozone generator should be turned off when
the instrument is not in use to reduce maintenance requirements.
WARNING
Chemiluminescence Reaction Cell and Photomultiplier Tube
Sulfur monoxide (formed in the Burner) and ozone (produced in the ozone
generator located in the Detector) are mixed in the reaction cell. The cell is
designed such that the reaction between SO and O occurs directly in front of
3
the photomultiplier tube (PMT). A UV band pass filter (300 - 400 nm) located
between the reaction cell and the PMT selectively transmits the light emitted
by the SO/O reaction. Efficient combustion in the ceramic tubes coupled with
3
the UV band pass filter eliminates interference from non-sulfur containing
analytes (e.g. nitric oxide, olefins, etc.) which also undergo chemiluminescent
reactions with ozone. A background signal is typically present as a result of
ozone-wall interactions and low level sulfur contamination of Detector gases.
This background signal can be used as a troubleshooting aid (see Section 10).
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10
5
9
4
3
6
6
2
7
1
8
1. Ozone Generator
6. Vacuum Line
7. Particulate Filter
2. High Voltage Transformer
3. Photomultiplier Tube Socket
8. Pre-Ozone Restrictor
9. Post-Ozone Restrictor
10. Pressure Transducer
4. Photomultiplier Housing
5. Reaction Cell
Figure 3 355 SCD Left Side
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18
17
IN OFST
RV1
OUT OFST
RV2
11
I
AMP
TP10
1
TP8
TP12
TP2
TP13
OUT
TP5 TP4TP6 TP7
TP2
TP3
TP4
TP3
ALCO
13
TP5
TP1
TP12
12
HV/100
TP11
TP8
TP13
TO
GND
FRONT
TP1
PANEL
TP14
TP9
TP9
USA
TP10
TP6
TP7
TP16 TP15
TP11
SIEVERS RESEARC
ELECTRONICS
16
RV1
HV
LOAD
P4
NEUT
P5
PUMP
OUT
WHT
OZONE
PUMP
LOAD
P6
NEUT
P7
OZONE
GEN
WHT
15
LINE
P2
NEUT
P3
AC
WHT
14
11. Amplifier Cable
12. HV Cable
15. Fuses
16. Pressure Regulator
17. Transfer line
13. PMT Amplifier
14. EMI Filter
18. Front panel display
Figure 4 355 SCD Right Side
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Figure 6 255 NCD Right Side View
Pressure Transducer
Vacuum in the reaction cell is measured using a pressure transducer. The
pressure of the reaction cell can be monitored from the front panel and will
typically range from 5 to 10 torr depending on the type of vacuum pump used,
condition of the chemical (ozone) trap, ceramic tube position and the
condition of the combustion chamber. The range of response is from 0 to 760
torr.
Vacuum Pump
There are two choices of vacuum pumps for the 355 SCD and 255 NCD. A
two-stage, oil-sealed rotary vacuum pump is used to produce an operating
pressure between 3 and 10 torr in the reaction cell. The oil-free Dry Piston
pump produces a vacuum between 5 and 12 torr. All vacuum pumps serve the
same purpose:
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• Collection and transfer of the combustion gases from the Burner to the
reaction cell.
• Transfer of ozone from the ozone generator to the reaction cell.
• Reduction of non-radiative collisional quenching of the emitting species in
the chemiluminescent reaction cell.
The higher vacuum produced by the oil-sealed rotary pump facilitates a
shorter residence time in the reaction chamber, and therefore reduces the
incidence of collisional relaxation of the excited SO . This results in slightly
2
lower detection limits using the oil-sealed pump as compared to the oil-free
pump.
Chemical Trap
To protect the vacuum pump from exposure to ozone, a chemical trap is
located at the inlet of the vacuum pump. This trap contains a catalyst that
converts ozone to diatomic oxygen. This trap is a consumable part and should
be replaced every 90 days of continuous Detector usage.
Oil Coalescing Filter
The oil-sealed rotary vacuum pump is operated with the gas ballast partially
open to aid in the elimination of water produced in the Burner and transferred
to the pump. As a result of the open gas ballast and the high flow rates of
gases, oil vaporized in the pump can escape through the pump exhaust. To
minimize oil loss, an oil coalescing filter is placed on the pump exhaust to trap
vaporized oil and to return this oil to the vacuum pump oil reservoir. This is
not necessary for use with the oil-free pump. A replaceable element in the
filter is a consumable part and should be replaced every 90 days of continuous
use.
FID Adapter (Optional)
The Agilent 355 Sulfur Chemiluminescence Detector is designed to mount into
most GC detector ports and operate as a stand-alone sulfur detector. For some
applications it is desirable to monitor both sulfur and hydrocarbon
components using a single column without splitting. For this reason, Agilent
offers a few adapter kits to mount the Dual Plasma Burner onto a Flame
Ionization Detector for the simultaneous collection of FID and SCD
chromatograms. During dedicated SCD operation, 100% of the column effluent
passes through the Burner to the Detector. During simultaneous detection
approximately 10-20% of the FID exhaust gases are drawn into the Burner
through a restrictor, which reduces sulfur sensitivity to approximately 1/10 of
the signal observed in a dedicated SCD Burner.
NCD Reaction Cell
The model 255 NCD reacts nitric oxide from the Burner and ozone from the
Ozone Generator in the Chemiluminescence Reaction Cell. The reaction occurs
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directly in front of the photomultiplier tube (PMT). A red cut-off filter between
the reaction cell and the PMT selectivity transmits the light from the nitric
oxide and ozone reaction.
Efficient combustion in the ceramic tubes and the red cut-off filter eliminate
interference from non-nitrogen containing analytes (sulfur dioxide, alkenes,
olefins) that have chemiluminescence reactions with ozone.
A background signal is typically present as a result of ozone-wall interactions
and low level nitrogen contamination from carrier and detector gases. The
background signal is a useful troubleshooting aid.
NCD Photomultiplier Tube and Cooler
In the NCD, a red-sensitive PMT detects emissions from the nitric oxide and
ozone reaction. A thermoelectric cooler cools the PMT 40 °C below ambient
temperature to approximately -15 to -20 °C to reduce background noise from
the PMT. The cooler operates whenever the Detector is connected to AC power.
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25 psig max
25 psig max
S
S
Mass
flow
NC
NC
F.C.
F.C.
Mass
flow
Air
H2
P
Dual Plasma Controller
Dual
Plasma
Burner
355 SCD
Transfer
Line
Column
P
Reaction
Cell
PMT
Gas Chromatograph
Vent
Figure 7 Schematic for 355 SCD
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25 psig max
25 psig max
S
S
Mass
flow
NC
NC
F.C.
F.C.
Mass
flow
O2
H2
P
Dual Plasma Controller
Dual
Plasma
Burner
255 NCD
Transfer
Line
Column
P
Reaction
Cell
PMT
Gas Chromatograph
Vent
Figure 8 Schematic for 255 NCD, in Nitrogen Mode
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25 psig max
S
S
Mass
flow
NC
NC
F.C.
F.C.
Mass
flow
O2*
P
*Or O2, He, N2
Dual Plasma Controller
Dual
Plasma
Burner
255 NCD
Transfer
Line
Column
P
Reaction
Cell
PMT
Gas Chromatograph
Vent
Vacuum Pump
Figure 9 Schematic for 255 NCD, in Nitrosamine Mode
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Overview
Installation and start-up of the Agilent 355 SCD or 255 NCD by a qualified
Agilent Service technician is recommended. If you choose to install the
detector yourself, carefully read all of this chapter prior to installation of the
instrument.
Although every reasonable safeguard against shipping damage has been taken,
product damage may still occur due to excessive mishandling. If obvious
damage has occurred during shipment, contact Agilent. Shipping materials for
the 355 SCD or 255 NCD should be saved. If the instrument must be returned
to the factory, it must be packed in the original carton to reduce the chance for
damage during shipment. Replacement shipping containers can be purchased
from Agilent.
Substituting parts or performing unauthorized modification to the instrument may result
in a safety hazard.
WARNING
WARNING
Hydrogen is a flammable gas. Perform periodic leak tests to verify there are no leaks in
the hydrogen lines and connections. Before making any connections, shut off the hydro-
gen supply. Connect or cap all fittings at all times when using hydrogen.
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Step 1: Selecting a Location
The instrument should be placed on a clean, unobstructed surface
approximately 22" (55 cm) deep by 10" (24 cm) wide that can support 44
relationship between the major system components. To facilitate proper heat
dissipation, an additional 1-2" (2.5-5.0 cm) should be available at the rear and
on both sides of the instrument. Distance between the SCD and the GC is
limited by the length of gas and heater lines.
Position the Controller on top of the Detector box or in another convenient
location near both the Detector and GC. The Controller requires supplies of
hydrogen and oxidant (air for the SCD and oxygen for the NCD). The length of
the gas inlet lines limit the distance between the Controller and the Burner to
approximately 1 meter.
There are two pump options for the Detector, each with different size
requirements. The Edwards RV5 oil-sealed vacuum pump requires a 6.3"
(16cm) by 18.5" (47cm) area on a shelf or a nearby floor and a minimum height
clearance of 22" (58 cm). The pump weight is 52 lbs (24 kg). The Dry Piston
Pump (oil-free) requires a 9" (22 cm) by 14" (35 cm) area on a shelf or a nearby
floor and a minimum height clearance of 12" (30 cm). The pump weight is
30 lbs (13.6 kg). The distance to the 355 Detector for both pump options is
limited by the power cord connection—6 ft (2 m) for the oil-free piston pump or
8 ft (2.4 m) for the oil-sealed vacuum pump.
Consider placing the oil-sealed pump over a plastic or metal container to capture any oil
leaks or spills.
NOTE
Power Requirements
required.
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Figure 10 Drawing of the Detector with Dual Plasma Burner and Controller
Environmental Considerations
The instrument should be operated in an environment which is comfortable
for human habitation with reasonably constant temperature and humidity.
Operation of the instrument at elevated temperatures (>30 °C) may result in
an increased background noise from the photomultiplier tube.
Combustion Gas Requirements
The Agilent 355 SCD and 255 NCD both require a hydrogen source; the 355
SCD requires an air source, and the 255 NCD requires an oxygen source.
Oxygen may be used for the ozone generator in either Detector to obtain a
modest increase in sensitivity; the Dual Plasma Burner was designed for use
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with air as the oxidant in the SCD and oxygen as the oxidant in the NCD.
For the SCD, detector gases must be sulfur free (<1ppb) for proper Detector
operation. In general, bottled air is preferred to “house” air from a compressor
because compressors tend to generate lower quality air. In addition, pressure
fluctuations induced by the air generator may be detrimental to Detector
performance.
For the NCD and GC, use gases that are low in nitrogen and total
hydrocarbons. Use gases with an "instrument" or "chromatographic" purity
rating. Agilent recommends gases with a purity range of 99.995% to 99.9995%.
Do not use oil-pumped supplied air since it contains large concentrations of
hydrocarbons.
Use of appropriate traps on carrier, hydrogen and oxidant sources to improve
support gas quality, such as a sulfur trap gas purifier, is recommended. The
oxidant used to supply the ozone generator should be dry to prevent internal
corrosion. Use of a moisture trap or dryer is recommended.
Two-stage pressure regulators
The combustion gases must be supplied to the Controller at a pressure of
25 psig or less. Use a two-stage pressure regulator rather than a single-stage
regulator to eliminate pressure surges. High-quality, stainless-steel
diaphragm-type regulators are recommended. On/Off valves at the regulators
are useful but are not essential. Mount the valves at the outlet fitting of the
pressure regulators.
If you use gases with a two-stage regulator up-stream, it will be sufficient to
use single-stage regulators at the Detector.
Particle Filtration
Up-stream, inline particle filtration of 10 micron or better is required to
prevent damage to Controller and Burner components.
Ozone is a hazardous gas and a strong oxidant. Minimize exposure to ozone by using the
instrument in a well-ventilated area and venting the exhaust of the vacuum pump to a
fume hood. Turn off the ozone generator when the instrument is not in use.
WARNING
Supply Tubing for Combustion Gases
Use preconditioned and cleaned copper or stainless steel tubing to supply
gases to the 355 SCD and 255 NCD. Do not use ordinary copper tubing since it
contains oils and other contaminants. Plastic tubing is not recommended since
it is permeable to oxygen and other contaminants that can damage columns
and detectors or cause elevated background. Teflon tubing may be acceptable
in some clean environments.
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Secure all gas cylinders to an immovable structure or permanent wall. Store compressed
gases in accordance with all safety codes.
WARNING
WARNING
Wear eye protection when using compressed gas to avoid possible eye injury.
Venting Gases
During normal operation of the GC with the SCD, NCD, FID, other detectors
and split/splitless inlet purge, some of the carrier gas and sample vents
outside the GC. In addition, the vacuum pump will vent a small amount of
ozone and other combustion products. If the components of the sample are
toxic or noxious, vent the exhaust from the GC outlets to a fume hood. Also,
vent the exhaust from the vacuum pump to a fume hood.
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Step 2: Unpack and Inspect the Instrument
Before unpacking boxes, inspect them for signs of physical damage. If damage
is observed, photographs should be taken in order to make a claim with the
carrier should any equipment damage be found. Check contents of boxes
against the shipping documents. Contact Agilent as soon as possible should a
discrepancy be found.
Required Installation Tools
The following tools are recommended for installation of both the 355 SCD and
255 NCD:
• One adjustable wrench, with adjustment up to 1 inch (2.5 cm)
• One 1/4"-5/16" open-end wrench
• Two 3/8"-7/16" open-end wrenches
• Two 3/4"-9/16" open-end wrenches
• One 5/8" open-end wrench
• One 1/4" Nutdriver with hollow shaft (for FID restrictor)
• One Phillips head screwdriver
• One pair cotton gloves (for hand protection)
• One small flat-head screwdriver
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Step 3: Set Up the Vacuum Pump
Initial connections require access to the rear of the Detector and the vacuum
pump. Follow the installation instructions for either the RV5 Edwards pump
or the oil-free dry piston pump, depending on your configuration.
Exhaust gases from the pump should be vented to a fume hood to eliminate any potential
hazard.
WARNING
Installing the Edwards RV5 Pump Oil-Sealed Vacuum Pump
The normal surface temperature of the pump body at ultimate vacuum (operation) at
WARNING
ambient temperature of 20 °C is 50 °C to 70 °C. If you use the pump at a high ambient tem-
perature, the temperature of the pump body may exceed 70 °C, and you must fit suitable
guards to prevent contact with hot surfaces. For more information refer to the pump oper-
ating manual.
Do not operate the vacuum pump with the oil level below the minimum oil level mark or
above the maximum oil level mark.
WARNING
1 Install the chemical trap mounting bracket to the top of the pump with the
screws and provided wrench. The chemical trap is a white plastic cylinder
approximately 1 foot (30 cm) in length by 1.5 inches in (3.8 cm) diameter
2 Remove the protective cap from the pump inlet port.
3 Install the metal conical screen and black centering o-ring into the pump
4 Attach the aluminum 1/2-inch barbed adapter to the pump inlet port with
the metal clamping ring.
5 Slide the 2 inches Tygon vacuum hose over the pump inlet barbed adapter
and secure with a hose clamp.
6 Slide another hose clamp over the 2 inches Tygon vacuum hose.
7 Remove the plastic caps from the barb fittings on the ends of the chemical
trap.
8 Press the trap into the mounting bracket and the 2 inches of Tygon vacuum
9 Tighten the hose clamp.
10 Locate the Oil Return Line Kit.
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11 Remove the drain plug and the bonded seal from the oil mist filter. The
bonded seal looks like a metal washer with a black inner o-ring.
12 Install the bonded seal to the oil mist filter drain adapter. The drain adapter
looks like a drain plug with a small plastic nozzle.
13 Screw the black drain adapter and bonded seal into the oil mist filter.
14 Remove the plastic protective cover from the pump exhaust port. Place the
15 Place the oil mist filter onto the o-ring on the pump exhaust port. Install the
filter so that the gray half is above the white half of the filter (see Figure 11
16 Position the oil mist filter so the drain adapter points toward the gas ballast
17 Fit the clamping ring onto the adapter and oil mist filter and hand tighten.
18 Turn the gray plastic gas ballast knob counterclockwise to position II. Press
the knob down against the spring and continue to turn counterclockwise
until the knob is free. Remove knob from the pump. Confirm that the
spring is still in place.
19 Locate the tall aluminum gas ballast control assembly, and install the small
o-ring into the groove on the shaft.
20 Insert the gas ballast control assembly into the pump, pressing down
against the spring, and turn it clockwise until the nozzle on the assembly is
directly over the mark on the top of the pump.
21 Cut approximately 3/4 of the black silicone oil return line and insert the
steel restrictor approximately half-way into the line. If needed, use a small
screwdriver or other small tool to aid in positioning the restrictor.
22 Fit one end of the oil return line to the drain adapter on the oil mist filter.
Fit the other end of the line to the nozzle on the gas ballast adapter. Ensure
that the tubing is not tight and has no tight bends. Secure the line at each
end, using the black hose clips provided.
23 Add oil to the pump via either of the two oil fill caps. The oil level should be
between one-third and one-half when viewed in the oil sight glass. Replace
the oil fill cap prior to operation of the pump.
Do not operate the vacuum pump with the oil level below the minimum oil level mark or
above the maximum oil level mark.
WARNING
24 Place a hose clamp over the black heat shrink end of the 6’ Tygon vacuum
hose, and connect the hose to the barbed fitting labeled Exhaust on the
back of the Detector. Tighten the hose clamp securely.
25 The SCD should be placed near the GC and be accessible from the rear in
order to connect the electrical power and the recorder signal cable.
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26 The vacuum pump should be placed within approximately 3 feet of the
Detector (elevation not important), in order to connect the vacuum hose
from the back of the Detector to the chemical trap. A hose clamp should be
placed over the hose, and the hose should be connected to the straight end
of the chemical trap. Tighten the hose clamp securely.
Vent the exhaust gas from the vacuum pump to fume hood to eliminate any potential haz-
ard.
WARNING
27 Place the vacuum pump in an adequately ventilated area or connect an
exhaust line (not provided) to the outlet located at the top of the mist filter.
Attach an aluminum 1/2-inch barbed adapter to the outlet with the metal
clamping ring and another centering o-ring. Secure the exhaust line with a
hose clamp (not provided) to the aluminum adapter. Route the exhaust line
to a fume hood or other suitable discharge location.
water to condense in the exhaust line and drip back into the coalescing
filter. Alternatively, install a water trap using a vacuum flask after the
coalescing filter to capture excess water and prevent water from dripping
back into the coalescing filter.
It is imperative that water does not condense in the exhaust line and fall back into the
mist filter. It is recommended that transparent 3/8 inch (0.95 cm) id tubing be used as an
exhaust line.
WARNING
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Chemical
Trap
Ballast control
Oil return line
Oil mist
filter
Mounting
Bracket
Power switch
EDWARDS
Edwards
Mode selector
Figure 11 RV5 Oil-Sealed Vacuum Pump and Associated Traps (Front Side)
Chemical Trap
Ballast Control
Barbed VacuumInle
Oil Return
Line
Oil Mist
Filter
EDWARDS
Power
Plug
5
Figure 12 RV5 Oil-Sealed Vacuum Pump and Associated Traps (Back Side)
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Gas ballast
Inlet &valve
Pump exhaust
Retractable handle
Chemical
Trap
Oil fill caps
Pump inlet
Figure 13 RV5 Oil- Sealed Vacuum Pump and Associated Traps (Top)
Sometimes water condensation and accumulation are visible in the exhaust line. This is
normal. However, do not allow water to continue to accumulate after approximately one
week of operation. Significant water accumulation may indicate improper pump operation,
an improperly vented exhaust line, or a Burner leak. Water accumulation in the exhaust line
can cause damage to the pump, especially if allowed to fall back into the pump. Contact
Agilent for advice if water accumulation continues to occur.
NOTE
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Figure 14 RV-5 Oil-S ealed Vacuum Pump Exhaust Line
Setting the Gas Ballast Position (RV5)
Set the mode selector halfway between the High Vacuum mode, the small 6
selector to the High Throughput mode, the large 6 symbol.
The RV5 vacuum pump and the Oil Drain Kit with ballast flow control ensure
the vacuum pump operates continuously with a gas ballast flow. The purpose
of the ballast control is to sweep ambient air into the pump oil. The air purges
the water (created from the combustion of air and hydrogen in the Burner)
and the oil (vaporized by the pump) into the oil coalescing filter. The filter
separates the oil from the water, vents the air and water, and returns the oil to
the vacuum pump.
The Oil Drain Kit with the ballast control continuously returns trapped oil in
the oil mist filter to the vacuum pump. This feature reduces oil loss from the
pump and minimizes the need to refill the pump with oil.
The Oil Drain Kit with the ballast control supplied is configured so that the gas
ballast flow rate is equivalent to that with the gas ballast control on the pump
in position II. For most applications, there is no need to change the gas ballast
flow rate. If required, the gas ballast flow can be adjusted using the following
procedure.
1 The restrictor plate on top of the aluminum ballast control has three
screws. Remove the three screws that secure the restrictor plate. Do not
2 The restrictor plate has circular indentations. The position of the
indentations with respect to the indentation on the side of the oil return
assembly identifies the gas ballast flow setting. Turn the restrictor to the
required position:
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• To select no gas ballast flow (not recommended), turn the restrictor
plate so that none of the indentations are aligned with the indentation
on the side of the oil return assembly.
• To select low gas ballast flow, turn the restrictor plate so that the single
indentation on the restrictor plate is aligned with the indentation on the
side of the oil return assembly.
• To select high gas ballast flow (the setting the ballast control is shipped
from the factory), turn the restrictor plate so that the two indentations
are aligned with the indentation on the side of the oil return assembly.
Installing the Welch Dry Piston Vacuum Pump
The Welch Dry Piston Pump may be used as a direct replacement for an
oil-sealed vacuum pump for the NCD or SCD. This pump produces all the
advantages of an oil-free pump with little or no loss in instrument
performance, however, operating Detector and Burner pressures will typically
be a few Torr higher than those obtained with the oil-sealed pump.
To install the dry piston vacuum pump, follow these steps:
1 Remove the pump from its packaging and place on an accessible work
surface with the power cord side nearest to you and the pump "INLET" port
2 Verify that the voltage of the pump matches that of the Detector.
3 Open the plastic bag containing the Dry Piston Pump Kit. Locate the brass
elbow and brass barb (3/8" NPT). Remove their plastic protective caps and
wrap three or four turns of Teflon tape (not supplied) onto the threaded
connections. Screw the barb fitting into the elbow and tighten using
wrenches. Similarly, remove the plastic cap from the pump's inlet fitting
and screw elbow into it. Tighten the elbow so that the barb ends up pointed
parallel to the floor and pointed toward the power cord side of the pump.
4 Locate the mounting brackets, 4 small screws and washers and spring clips.
Use 2 screws and washers to attach the spring clips, one to each bracket.
5 Using the supplied Torx wrench, remove two Torx screws from the pump,
the right corner screw located closest to you and the closest screw to you
located immediately to the left of the pump's handle.
6 Attach the brackets to these locations using the Torx screws as showing in
7 Attach the short piece of ½" ID hose tubing supplied in the Dry Piston
Pump Kit to the brass barb and use one of the supplied hose clamps to
tighten it onto the barb.
8 Place a second hose clamp over the other end of the plastic tube. Insert the
barb on the elbow end of a Chemical Trap into the open end of the short
plastic hose that was just attached to the brass barb on the pump.
9 Rotate the Chemical Trap so that it is retained by the spring clips.
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10 Tighten the hose clamp located on the plastic tube and the elbow barb end
of the Chemical Trap.
11 Remove the plastic cap from the inlet end of the Chemical Trap. Taking the
clear end of the vacuum hose and another hose clamp attach the vacuum
hose to the inlet end of the Chemical Trap and tighten the hose clamp.
12 Attach the black end of the vacuum hose to the barb fitting located on the
back of the Detector box and tighten the last hose clamp onto it to make this
connection.
13 Using three or four wraps of Teflon® tape around NPT fitting of the
supplied muffler or user supplied exhaust fitting to the pump's "EXHAUST"
port. Any exhaust tubing attached to the pump exhaust should be
positioned to avoid the accumulation of water from condensation of water
vapor.
Vent the exhaust from the vacuum pump to a fume hood or other exhaust system to elimi-
nate any potential hazard.
WARNING
14 Place the vacuum pump where it will be located when the pump is
operated, within the length of the power cord to be attached to the female
connector on the back of the Detector.
15 Make sure that the On/Off switch on the pump is in the on position.
Operation Notes (Welch Pump)
1 The pump is designed to start against atmospheric pressure. Therefore, if
the pump is turned off inadvertently, it may be necessary to allow the
Detector pressure to rise before restarting the pump.
2 The only user maintenance required is the periodic replacement of the
piston sleeves and seals, e.g., after 8 months of continuous operation.
Consult the pump’s manual for further details.
3 Although, the pump is not damaged by exposure to ozone, use of the
Chemical Trap is highly recommended. Refer to the pump manual and seal
replacement kit instructions for more detailed information.
4 High line voltage will cause the pump to overheat and trip its thermal fuse.
5 When new, or after changing seals, the pump may require a short break-in
period (2-4 hours).
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Figure 15 The Welch Dry Piston Pump
Screws
Indentation
(Low Ballast)
Indentation
(High Ballast)
Restrictor Plate
Indentation
(Alignment Guide)
Figure 16 Oil Drain Kit with Ballast Control
6 Turn the switch on the vacuum pump to the On position.
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Note the position of the oil level in the window after operating the pump for
several hours. For the next several days of operation, recheck the oil level
daily. If the oil level is increasing, water is accumulating in the oil reservoir.
Confirm that the water vapor is properly being expelled from the oil mist
filter. If the oil level is dropping, excess air flow through the pump is forcing
oil out of the vacuum pump. Turn the restrictor plate so that the single
indentation on the restrictor plate is aligned with the indentation on the
side of the oil return assembly. After adjustment of the gas ballast, allow the
system to operate for an additional day and check the oil level again.
It is normal for the oil to appear foamy from air in the oil when viewing the oil
in the oil level window. The purpose of the ballast control is to sweep ambient
air into the pump oil. Ensure the oil level when the pump is operating is not
above the “Full” mark on the pump.
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Step 4: Connect the Power Cord
Connect the pump power cord to the female socket on the back of the Detector
and this switch should be turned On. Do not connect to the AC power supply at
this point in the installation procedure.
AIR INLET
RECORDER
OUTPUT
10V
EXHAUST
1V
100mV
FUSE 250 VOLTS
10 AMPS
VACUUM
PUMP
Voltage Label
Figure 17 SCD (230 V Unit) Rear Panel Diagram
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Step 5: Install the Dry Compressed Air or O2 Supply
Connect a 1/8" OD Teflon (PFA) line fitted with a 1/8" brass Swagelok nut from
compressed air or oxygen. The air regulator located inside the front door of the
Detector should be set to approximately 3-6 psi.
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Step 6: Install the Signal Output Cables
Signal output cables are available from Agilent as standard equipment and can
be used with most data systems. Confirm that the output cable supplied is
correct for your system. A standard cable fitted with two crimp lug connectors
is supplied for use with most integrators, recorders or data systems. Attach
the BNC connector end of the recorder cable to the matching output
connector, labeled RECORDER OUTPUT, on the back of the SCD (see
Standard Cable Connection
The standard recorder cable is connected to the integrator by installing the
red crimp-lug connector to the signal terminal (+) and the black crimp-lug
connector to the negative terminal (-). No additional ground connection is
required.
HP 3390 Series Integrator Cable Connection
The keyed-edge connector on the HP 3390 series cable is attached to the signal
input of HP 3390 series integrators. Note that the connector can only be
installed one way.
HP 3396 Integrator Cable Connection
The jack plug on the HP 3396 cable is attached to the analog signal input
connector at the rear of the integrator. This cable also works with the Agilent
35900 controller.
HP 5890 GC Analog Input Board
A cable made specifically for this input board is available. This board is used
when the SCD signal is input to ChemStation.
Agilent 6890 GC Analog Input Board
A cable made specifically for this input board is available. This board is used
when the SCD signal is input to ChemStation.
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Step 7: Install the Dual Plasma Burner
Remove the cover plates from the Detector area of the GC to expose the hole
into the oven through which a Detector is normally mounted. If the GC has
more than one available Detector position, pick the most convenient one.
that mounting fastener patterns will vary by GC manufacturer. Make sure the
notch in the inside liner is on the right, in order to accommodate the geometry
of the Burner as it sits in the shroud and mounting plate.
Figure 18 Dimensions of GC Liner Cut-Outs
Align the Burner mounting plate with the mounting screw holes on the GC.
Clear the hole into the GC oven of interfering insulation, and then secure the
mounting plate onto the oven with the screws provided. Attach the Burner's
heated base connector to the GC's temperature control circuit. Consult your
GC's operation or service manual to confirm proper connection of the 100 ohm
RTD sensor and the cartridge heaters.
Occasionally geometric design changes will occur within or between GC models. If the
mounting plate provided does not match up with the top of the GC, contact Agilent for
additional information.
NOTE
Position the Dual Plasma Burner (column end down) into the tapered fitting of
the heated base, with the lower hydrogen line and pin aligned with the slot in
the heated base. The Burner should be secure when properly positioned.
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Step 8: Install the Dual Plasma Controller
Position the Controller such that the gas lines from the Burner can be easily
attached to the back of the Controller. Connect the Controller to both a
hydrogen source and an oxidant source, per Step 1. Connect the gas supplies
to the 1/8" bulkhead unions marked "Oxidizer Inlet" and "Hydrogen Inlet."
Clean copper tubing (1/8" OD) is recommended.
Connect the two 1/16" gas delivery lines (provided) from the Burner to the
appropriate fitting on the rear of the Controller marked Oxidizer or Hydrogen
in the Outlets (to Burner) area. Use a 1/4" open-end wrench to tighten the nut
onto the bulkhead unions, using a 9/16" wrench to back-up the union.
Connect the yellow thermocouple plug from the Burner to the thermocouple
jack at the rear of the Controller. The thermocouple connector will only fit one
way, with the iron terminal (the one with the two grooves) down. Connect the
Burner heater line to the two pin locking connector on the back of the
Controller.
The Controller can be used for either 100/115 or 230 VAC. The correct voltage
for your Controller is set at the factory; however, this should be verified upon
installation. The voltage selection is shown through a small window on the
make sure that the proper fuses are installed. Contact Agilent for a
replacement fuse set.
Do not change the voltage selector without changing the main power fuse. Operating the
Controller box without the proper fuse may damage the electronics.
WARNING
Figure 19 Dual Plasma Controller Rear Panel
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Step 9: Install Column Connections
The Burner operates under reduced pressure and there will be a slight vacuum
on the end of the column. If a higher outlet pressure for the column outlet is
desired, fused silica capillary restrictors may be attached to the end of the
analytical column (both capillary and packed) prior to making the Detector
connection.
Capillary Columns
Place the column nut over the end of the capillary column. Place the
appropriate fused silica adapter ferrule onto column. Remove a few
centimeters from the end to remove any particles that may have entered the
column. Insert the GC column into the Burner by 108-109 mm from the upper
end of the nut (114-115 mm if measured from the flat bottom of the nut). Do
not force the column. The pathway is narrow and may take several tries to seat
it correctly. Tighten the column nut finger tight, or until sealed using a 7/16"
open-end wrench to back-up the hydrogen inlet fitting to prevent it from
slipping.
108-109 mm
114-115 mm
Figure 20 Measuring Column Insertion
Packed Columns and Columns with an Outside Diameter > 0.8 mm
Connect a short piece (0.5 m or less) of deactivated fused silica tube, for
example 0.32 mm internal diameter, to the Detector end of the column. Follow
the procedure for capillary column connection as above.
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Step 10: Install the Transfer Line
Connect the black transfer line (extending from the side of the Detector) to the
top connector on the Burner and tighten with a 3/8" open-end and 7/16"
open-end wrench (backing up the union on top of the Burner to prevent its
position form slipping).
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Detector Front Panel Controls
control, display output control, and power control. Each section is described
below. All the front panel LEDs are red in the ON mode and darkened in the
OFF mode except for POWER. This LED toggles green for ON and red for
STANDBY. In STANDBY mode, the front panel display and high voltage to the
photomultiplier tube (PMT) are turned off. The red LED in the STANDBY mode
serves as a reminder that power is still supplied to the instrument.
Figure 21 Front Panel Controls
Power Controls
ON: Turns on front panel displays and high
voltage to the PMT.
STANDBY: Darkens panel and turns off high
voltage to the PMT. Does not shut off main
power.
Turns pump ON (red) and OFF (dark).
Functions in both ON and STANDBY modes.
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Turns ozone generator ON or OFF.
Functions in both ON and STANDBY modes if the
pump is producing sufficient vacuum.
Display Output Controls
Controls the range of the front panel display
between high sensitivity (0.1-200mV) and low
sensitivity (0-2V). Does not affect recorder
output signal.
Displays the output signal of the SCD in
millivolts. (Note: Changing the output range of
the SCD by adjusting the recorder switch on the
back panel does not change the range of the
display.)
Displays the pressure of the chemiluminescence
reaction chamber in Torr (mm Hg)
Signal Controls
The SCD and NCD use analog amplifier circuitry for the measurement of the
current produced by the photomultiplier tube. Two Front Panel Controls are
used to adjust the output signal of the Detector.
Changes the gain of the amplifier by a factor of
100. For high sensitivity measurement of sulfur
or nitrogen compounds (measurement of low
levels of sulfur or nitrogen compounds), the
attenuation should be operated in the 1 position.
For samples containing high levels (ppm to
percent) of sulfur or nitrogen compounds, use
the 100 position.
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The baseline signal from the SCD and NCD can be
adjusted from 0 to 1% of the full scale recorder
output using the offset control. (e.g., +10 mV to
-10 mV for a 1 V full scale setting). This control
can be used to offset the background signal.
Dual Plasma Controller Controls
The Agilent Dual Plasma Controller provides easy access to basic settings.
Figure 22 Dual Plasma Controller Front Panel
Oxidizer and
Hydrogen Control
Knobs
Allow you to adjust the oxidizer and hydrogen flow
rate.
Temperature Control
Knob
Allows you to adjust the Burner temperature.
Selector Control Knob Changes the display to show the current value or
set point for each setting (temperature in °C,
pressure in Torr, oxidizer in sccm, or hydrogen in
sccm).
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Controller Status
Lights
Illuminate to reflect current status. The Power LED
indicates power is on; the Heater LED indicates
temperature set point has been obtained; the Valves
LED indicates the solenoid valves open; and the
Fault LED indicates a drop in pressure or excessive
details).
Initial Startup
Vacuum Test
With the 1/8" Valco cap on the black PFA transfer line still in place and the air
supply to the ozone generator off, set the internal air regulator to 0 psi (fully
counterclockwise), and power on the SCD or NCD by plugging the power cord
into the house power supply. The SCD and NCD will power up in STANDBY
mode, with the pump and the ozone generator OFF. For this test, the desired
mode is power ON, vacuum pump ON, ozone generator OFF, display range in
the low sensitivity mode and PRESSURE signal displayed. Press the following
controls in the order shown in order to start the vacuum pump and to view the
reaction cell pressure.
Press until green ON LED is lit
Press until red LED is lit
Press to display reaction cell pressure in torr
After the pressure has stabilized ( 5 minutes), record the pressure below.
~
Typical pressure in the reaction cell should be 1-2 torr with the oil-sealed
pump, or 5-8 torr for the oil-free pump.
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Reaction cell pressure, with air to ozone
generator OFF (0 psi setting on internal
regulator) and transfer line capped: ___________________ torr
Tighten connections if necessary and check to make sure pressure stabilizes in
the expected region. If proper pressure is not obtained contact Agilent for
assistance. If the reaction cell pressure is within the expected range, record
the value, reset the internal air regulator to 3-6 psi, turn the pump OFF and
proceed with the recorder test.
Recorder Test
The standard 355 SCD and 255 NCD recorder output configuration is 1 volt full
scale. In addition, an output range can be set with the recorder output
screwdriver to adjust the switch to the proper position for your integrator or
data system.
To check that the recorder cable has been properly connected to the integrator
or data system, set the integrator to a high sensitivity setting (e.g. attenuation
of x 1) and plot the background signal. Use the Output Offset to decrease the
Detector baseline. If the recorder cable is connected correctly, the baseline will
shift in response to changes in the Output Offset. If the polarity of the
connection is incorrect, a negative response will be observed when the
baseline is increased, and vice versa. Switch the polarity of the wires to
correct this problem. If no response is observed, re-check the signal
connections and repeat the test. Contact Agilent if there is no data system
response after completion of this test.
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Detector Interface Setup
Initial Checkout
Careful attention to eliminating leaks in the Detector interface will lead to
better Detector sensitivity and easier troubleshooting if problems develop.
1 Check that the gas connections have been made correctly and that they are
tight.
2 Plug the 3-prong connector for power on the Controller into a 100-volt,
50/60 Hz, 115-volt, 50/60-Hz or 230-volt, 50/60 Hz AC outlet.
3 Connect the oxidant delivery line to the oxidant inlet nut on the Burner.
Leave the heater cable disconnected and the thermocouple plugged in.
4 Connect the black PFA transfer line from the Detector to the top of the
5 Turn on the Controller, the Detector power, and the vacuum pump.
6 Let the system pump down to a stable pressure ( 5 minutes).
~
7 Read the pressure from the LCD display on the Controller. It should be <30
torr, with higher pressures observed for packed or megabore columns due
to the higher column flow. Record this pressure for reference.
Pressure of Burner with column flow but without hydrogen
and oxidant flow to Burner:_________ torr
The reaction cell pressure on the Detector should be less than 5 torr
(10 with oil-free pump).
8 If pressure readings are not within the above specifications, then there are
leaks in the system. Leak check all positive pressure points (swage nuts,
tees, crosses) with SNOOP or a leak Detector. Tighten fittings if necessary
and recheck the pressure. Confirm that the Burner fittings (oxidant inlet
nut, tee, and hydrogen nut) are strongly hand-tightened. If necessary,
tighten the gas delivery lines and transfer line. If pressure readings are still
high, contact Agilent for service.
Do not overtighten! Overtightening the fittings on the ceramic tubes can cause the tubes
to break. Vespel ferrules that are greatly distorted by overtightening cannot be used
again.
WARNING
9 Turn off the Controller and the vacuum pump.
10 Reconnect and/or turn on the hydrogen and oxidant supplies to the
Controller.
Adjust the hydrogen and oxidant inlet pressures to 25 psig (1.7 bar).
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Monitoring Oxidizer and Hydrogen Flow with the Dual Plasma Controller
Hydrogen will flow to the Burner only if the temperature is above 325 °C and
the pressure of the Burner is <575 torr.
Turn ON the vacuum pump at the Detector and the power to the Dual Plasma
Controller. The power LED should illuminate. When the temperature reaches
approximately 325 °C, the valve’s LED should illuminate, indicating hydrogen
and oxidant flow.
Use the Controller display knobs to select display of oxidizer or hydrogen flow.
Hydrogen gas is explosive and must be handled carefully. Keep away from sources of
ignition.
WARNING
The Burner is hot. Do not touch the Burner. Let the Burner cool before performing any
operations involving the Burner.
WARNING
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Start-Up Procedure
1 Turn on the GC and set the carrier flow rate.
2 Turn on the hydrogen and oxygen to the Dual Plasma Controller.
3 Turn the Detector from STANDBY to ON.
4 Press the PUMP button until the red LED illuminates. Make sure the
vacuum pump is running.
5 Turn on the oxygen to the ozone generator and set the regulator inside the
front door of the Detector to between 3 and 6 psig.
6 Allow the system to evacuate for approximately 1 minute before turning on
the ozone at the front panel. A properly functioning system will show a
background signal deflection between the ozone on and ozone off.
7 Turn ON the Dual Plasma Controller using the ON/OFF switch on the rear
panel of the Controller. As the Burner heats, the SCD or NCD background
will increase and then slowly decrease. The hydrogen and oxidant flow will
automatically start when the temperature of the Burner rises above
approximately 325 °C.
8 Check the LCD display of Dual Plasma Controller to confirm that all
pressure, temperature, and signal responses are within the desired
specifications.
The Burner is hot. Do not touch the Burner. Let the Burner cool before performing any
operations involving the Burner.
WARNING
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Detector Operation
Detector Stability and Response
The time required for system stabilization varies depending on the application,
system cleanliness, presence of active sites and other factors. Useful results
could be generated within 30 minutes of start-up, especially with a previously
operated system. A longer stabilization time is likely to be required upon
changing critical system components, such as the combustion tubes or the GC
column. In addition, gas flow rates may drift initially as thermal equilibrium is
reached due to changes in gas viscosity with temperature. Therefore, it is good
practice to monitor gas flow rates and adjust them accordingly.
Even though a system may not be fully stabilized, sample injections can be
made within minutes of instrument start-up. Whether the results are useful
largely depends on application. Typically, an elevated baseline will initially be
observed, which will diminish upon successive programmed runs.
After stabilization has been reached, the system should exhibit good
short-term and long-term precision. Of course this also depends on the
application and concentration of components being measured. As an example,
analysis of thiophene in benzene at the 1 ppm sulfur level yielded 1.4% RSD
(n=10) over about 2 hours and 3.6% RSD (n=42) over about 96 hours. As
expected, carbon disulfide at a lower concentration of 90 ppb sulfur yielded
2.6% and 10.4% RSD, respectively.
Column Bleed
Accumulation of column bleed causes silicon dioxide to build up in the Burner.
This silicon dioxide creates active sites that are detrimental to performance. In
many cases, the choice of column can be optimized for a particular
application. Column bleed can be minimized by the use of oxygen traps on the
carrier gas, low-bleed columns, and lowest possible maximum oven
temperature.
Coking
Contamination from some sample matrices can reduce sensitivity. Crude oils
containing volatile metal complexes may contaminate ceramic tubes. The
incomplete combustion of certain hydrocarbon-containing compounds leaves
behind coke deposits on the tubes. Coke deposits may be removed from the
Burner by reducing the hydrogen flow rate. The Dual Plasma Burner is much
less susceptible to coke formation than other designs.
Hydrogen Poisoning
Hydrogen poisoning of the ceramic tubes occurs when there is no oxidizer flow
through the ceramic tubes. The result is extremely reduced, or no response.
Hydrogen poisoned tubes can not be reconditioned and should be discarded.
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Contaminated Gases
The use of clean gases for the 355 SCD is essential for optimal performance.
High purity gases (99.999% pure or better) are advised. Sulfur and other
contaminants from gases may accumulate in the column and bleed out over
time desensitizing the tubes and causing elevated baselines. The use of sulfur
traps is highly recommended for all gases.
Fluctuating Pressures
Fluctuations in pressure, especially from gas generators, will affect Detector
response. It is therefore recommended that only bottled gases equipped with a
dual stage regulator or appropriate steps to ensure stable pressure supplies
are used.
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Typical Operating Conditions
The Controller is calibrated at the factory for flow rates to deliver gas in sccm
units. The following table summarizes the typical operating conditions:
Table 1 Typical Operating Conditions
Condition
SCD
NCD
Detector Pressure (Torr)
4-8 (6-12*)
4-10
Dual Plasma Controller
Pressure (Torr)
300-400
100-250
Burner Temperature (°C)
Hydrogen Flow Rate (sccm)
Oxidant Flow Rate (sccm)
Background Noise (mV)
* Oil-free pump
800
900-950
4-6
40-50
60-65 (air)
0.3-2.0
8-12 (oxygen)
0.3-1.0
Thermocouple lifetime at 950 °C is diminished.
The recommended conditions should yield satisfactory results for most
applications and should be used as a typical starting point for any method
development. Like any detector, however, there are optimum conditions which
may very somewhat from the recommended conditions. In optimization of
conditions for the Dual Plasma Burner and Controller the following guidelines
should be considered:
High flow rates of hydrogen and oxidant can release enough heat at high
temperature to vaporize combustion tubes and cause blockages downstream
where the materials condense. High flow rates will eventually cause the
pressure in the Burner to exceed its fault cut-off limit of about 600 Torr. For
this reason, do not exceed the recommended flow rate by more than about
25%.
A higher hydrogen to oxidant ratio may initially show higher response but
later yield a reduced response because of the accumulation of contaminants,
such as soot or other active species, that reduce the Detector response.
Operating the Burner at higher temperatures will place more demand on the
heater, thermocouple and seal materials, effectively shortening their lifetime.
In general, when making any parameter change, keep in mind that the system
may require time to reach equilibrium.
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Detection Limits
The following table lists the detection limits which can be expected for typical
chromatographic conditions, assuming proper operation of the Detector and
chromatographic systems.
Table 2 Expected Detection Limits for Chromatographic Conditions
Type of Injection
Volume
Column
Detection Limit Per
Compound as Sulfur
Liquid, Split 1:10
1 µL
1 µL
Capillary ≤0.32 mm ID 50 parts per billion
Capillary ≤0.32 mm ID 0.5 parts per million
Capillary ≤0.32 mm ID 5 parts per billion
Capillary ≤0.32 mm ID 0.5 parts per billion
Capillary ≤0.32 mm ID 50 parts per billion
Liquid, Split 1:100
Liquid, On-column or splitless
Liquid, Splitless
1 µL
10 µL
1 cm3
1 cm3
1 cm3
10 cm3
Gas, Split 1:10
Gas, Direct on-column
Gas, Direct on-column
Gas, Direct on-column
0.53 mm ID
Packed
5 parts per billion
5 parts per billion
0.5 parts per billion
Packed
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Instrument Shut-Down
Daily Shutdown
1 Toggle off the ozone generator.
2 Turn off the air regulator (counter-clockwise), located inside Detector door.
3 Toggle power to "stand-by."
4 Leave the vacuum pump and Dual Plasma Controller operating at all times.
Complete Shutdown
1 Toggle off the ozone generator.
2 Turn off the air regulator (counter-clockwise), located inside Detector door.
3 Toggle power to STANDBY.
4 Turn off power to the Dual Plasma Controller.
5 After 15 minutes, toggle off the vacuum pump, so the Burner cools and
moisture is removed from the system.
6 Turn off gases to unit.
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Special Operating Modes
Using the 255 NCD in Nitrosamine Mode
By default, the 255 NCD is configured to detect nitrogen. To change from
nitrogen to nitrosamine mode, first turn off and unplug the Controller. Remove
the cover, find jumper P6 and the positions labelled High Setpoint and Low
Setpoint located on the printed circuit board near the left front of the
Controller. Move the jumper position from the High Setpoint to the Low
Setpoint position. This changes the temperature control range to 350-500 °C to
schematic drawing of the 255 NCD in nitrosamine mode.
Hydrogen is not used in the nitrosamine mode. Turn off and disconnect the
hydrogen inlet gas. Using the supplied tee, couple the oxidant outlet with the
two Burner inlets. Use of oxygen is recommended at 5-10 mL/min because the
Burner can easily be cleaned by raising the Burner temperature to about
900-1000 °C in flowing oxygen. Alternatively, helium or argon can be used,
however, these gases will not permit in situ cleaning at elevated temperature.
The presence of catalyst in the quartz combustion tube will generally yield the
highest sensitivity for nitrosamines. However, for some sample types that
contain potentially interfering nitrogen compounds, such as nicotine, it may be
desirable to remove the catalyst to obtain better selectivity. This is achieved by
removing the quartz combustion tube and using a straight 1/16" rod or tube to
push the catalyst out of the tube (save the catalyst for reuse or recovery as it
contains 90+% platinum). Replace the combustion tube and optimize the
burner temperature as desired (in general it is desirable to increase the
pyrolysis temperature by 50-100 °C when the catalyst is not used). Refer to the
regard to tube removal and replacement.
Using the SCD in High Sensitivity Mode for Nonhydrocarbon Gaseous Samples
There are circumstances in which it may be desirable to operate the SCD in a
non-typical manner. These could include the analysis of very low levels of
sulfur species in a nonhydrocarbon gas matrix, such as helium, carbon
dioxide, or even hydrogen. It should be possible to measure low ppb or high
ppt levels of sulfur species.
In the case of a hydrogen matrix, the sample matrix itself can suffice as the
lower source of hydrogen for Dual Plasma operation in a non-chromatographic
mode. For instance, a flow rate of nominally 20 SCCM of the sample, a
hydrogen calibration gas and a “clean” hydrogen source can be alternately
introduced to the Burner. The sample and calibration gas would be introduced
into the normal column connection. The side port of the splitter fitting would
be plugged and the clean hydrogen source would be plumbed to the lower
hydrogen inlet port. The upper hydrogen and air flow rates would be adjusted
to nominally 30 and 65 SCCM, respectively.
In the case of nonhydrocarbon gaseous samples, the potential for coking is not
a concern, so a Dual Plasma is not necessary. Some improvement in sensitivity
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can be achieved by eliminating the lower plasma. This is accomplished by
plugging the side port of the splitter fitting and teeing the air into the lower
hydrogen line, much like the configuration used for Nitrosamine analysis as
hydrogen flow rate of around 60 SCCM is used. Sensitivity of around 0.1 pg
S/sec or less should be readily achievable. It is not possible to cover all
potential applications, so some optimization may be desirable.
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Pump Maintenance
To maintain optimum performance of the Agilent 355 SCD and 255 NCD,
routine replacement of the chemical trap (for ozone destruction), oil
coalescing filter and oil (Edwards oil-sealed pump only) is necessary. Refer to
Table 3 for the expected life span of each replacement part or material.
It is beneficial to keep a maintenance log that tracks when maintenance is
performed and any instrument or operational changes that might impact
performance. Also keep track of detector flow rates (oxidizer and hydrogen),
pressures (burner controller and reaction cell in detector), and background
signal (the difference between ozone “on” and ozone “off”).
Table 3 Operating Life of Components for Edwards RV5 Vacuum Pump
Component/Material
Chemical Trap (RV5)
Oil Coalescing Filter (RV5)
Pump oil†
Operating life*
~ 3 month
~ 3 months
~ 3 months
* The operating life is based on the total time logged during operation of the Detector with the Burner and the
ozone generator ON.
† Pump oil can be purchased from a supplier or directly from Agilent: SAE 10W-30, Multiviscosity Synthetic
Motor Oil such as, MOBIL 1 or AMSOIL.
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Cleaning the Detector
You can clean the external housing of the Detector with a damp cloth using
water or non-abrasive cleaners. Turn off power to the Detector and disconnect
it from main power prior to cleaning. Do not spray liquids directly on the
Detector. Wipe dry with a clean, soft cloth.
No cleaning agents which could cause a hazard as a result of reaction with the
Burner unit are to be used in cleaning the instrument.
Contact Agilent to address concerns about the compatibility of specific
cleaning agents with the Burner unit.
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Changing the Oil Mist Filter (RV5)
The oil mist filter on the RV5 pump has two components: the charcoal odor
filter and the oil coalescing filter element. To replace the filters, disassemble
the oil mist filter assembly with the 4 mm long-handled allen wrench
(provided). The smaller charcoal odor filter sits on top of the larger oil
coalescing filter element. It is recommended to replace the oil coalescing filter
element after 90 days of continuous use, however replacement of the charcoal
odor filter is optional. After replacing the filter, re-assemble the filter
assembly and attach it to the pump flange.
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Reaction Cell Cleaning
Over time, the reaction cell and UV pass filter (SCD) or IR pass filter (NCD)
will develop a build-up of material which should be removed for optimum
sensitivity. The cleaning schedule depends upon Detector use and the nature
of the analyses; however, it is recommended the cell should be cleaned
annually. The cleaning procedure requires removal of the photomultiplier
tube (PMT) from the Detector, and special precautions are required to prevent
damage to the PMT.
Exposure of a photomultiplier tube to bright light can result in damage to the
PMT, even when the high voltage is off. To avoid potential damage, minimize
light exposure. The black PMT cover included in the Detector accessories
package is recommended for this procedure. Carefully read all the instructions
below before attempting to remove the PMT. If you have any questions
regarding this procedure please contact Agilent.
To clean the cell and pass filter:
1 Disconnect the main power cord (if the vacuum pump is operated from an
independent power outlet, unplug the power to the pump as well).
Any operation requiring access to the inside of the equipment, could result in injury. To
avoid potentially dangerous shock, disconnect from power supply before opening the
equipment.
WARNING
2 Remove the right side panel from the Detector and disconnect the high
voltage and coaxial signal cables from the rear of the PMT housing (See
3 Turn off all room lights and minimize outside light sources.
4 Unscrew the PMT socket connector assembly. Carefully pull the socket
assembly and the PMT out toward the rear of the instrument at a slight
angle to remove the PMT/socket assembly from the housing.
5 Immediately place the black PMT cap over the PMT, being careful to avoid
placing fingerprints on the PMT window. Do not remove the PMT from the
socket assembly. After the PMT cap is in place, carefully place the PMT and
socket assembly on a soft surface inside a drawer or other dark location to
minimize exposure of the PMT to light. The room lights may be turned on at
this point.
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PMT SOCKET
PMT HOUSING
PMT
FILTER
HIGH
VOLTAGE
SIGNAL
to power supply
to amplifier
PMT SOCKET
REACTION
CELL
Figure 23 Reaction Cell, PMT Housing and PMT Socket
PRESSURE
SENSOR
O-RINGS
REDUCING
UNION
TRANSFER
LINE
FROM OZONE
GENERATOR
Figure 24 Reaction Cell
6 Use a 7/64" Allen wrench to remove the three mounting screws from the
reaction cell. Slowly pull the reaction cell back from the PMT housing. The
optical filter is located between the reaction cell and the PMT housing.
Remove the optical filter from the housing by tipping up the back of the
Detector, if necessary, and allow the filter to fall onto a soft cloth.
7 Inspect the o-rings and replace them if they show any wear.
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8 Clean any deposits on the optical filter using a soft cloth or Kimwipe
dampened with methanol or deionized (DI) water. Do not leave fingerprints
or fibers on the cleaned filter. Deposits inside the reaction cell can be
cleaned in the same manner, however, care must be taken to avoid bending
the ozone inlet tube that extends into the cell.
9 Reseat the pass filter into the PMT housing. Confirm that the two o-rings
around the reaction cell are properly seated in the O-ring grooves (see
Figure 24). Carefully re-align the reaction cell to the PMT housing, making
sure the o-rings remain properly seated, and secure the cell to the housing
with the three screws. (The two o-rings must be correctly seated in order to
obtain a vacuum-tight and light-tight seal.)
10 To re-install the PMT, minimize all light sources. Remove the PMT cap,
being careful not to touch the PMT window. Insert the PMT and the socket
assembly into the PMT housing and screw in the socket assembly until it is
seated tightly against the housing. The room lights may now be turned on.
11 Reconnect the PMT high voltage cable to the MHV connector (longer
connector) and the PMT signal cable to the BNC connector (shorter
The high voltage and signal cables must be attached to the proper connectors on the pmt
socket; damage to the pmt will occur if the cables are not properly connected.
WARNING
12 While the side panel is still removed, reconnect the AC power cord to the
Detector and switch the front panel power to ON. To ensure that the o-rings
have been properly sealed, monitor the Detector baseline at "attenuation 1"
for several minutes (with the room light ON), and after noting the baseline
signal, turn the room lights OFF. If the baseline signal significantly
decreases, the o-rings are incorrectly positioned and the PMT must be
removed and the cell re-installed.
13 If no change in the baseline is observed, check the system for vacuum leaks
by turning on the vacuum pump and monitoring the pressure as described
in Section 7. If the pressure readings are comparable to start-up values, the
o-rings are properly positioned. If a significantly higher pressure is
observed, the PMT must be removed and the cell re-installed.
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Flow Sensor Calibration
The hydrogen and oxidant flow sensors installed in the Dual Plasma Controller
have very good repeatability, but significant non-linearity. They have each
been factory calibrated at the midrange flow rate (50 SCCM) using an NIST
traceable flow meter. Over the typical operating range for the SCD, the flow
sensors should produce accuracy of better than 10% of reading. However,
due to sensor non-linearity at low or high flow extremes, error greater than
this could be observed.
If greater accuracy is desired at a particular flow rate range, it is possible to
re-calibrate the flow sensors. A reference flow meter, appropriate gases, and a
trim-pot adjustment tool are required for this procedure. With the controller
on and no gases flowing, the zero calibration points are set with RP6 and RP4
for the hydrogen and oxidant flow streams, respectively. Connect a reference
flow meter to the gas outlet(s) on the back of the controller. Connect
pressurized gas line(s) to the inlets on the back of the controller. Connect
jumper (JP1) to bypass the pressure fault circuitry. Allow the burner
temperature to exceed 325 °C in order for the hydrogen and oxidant valves to
be open. The spans of the sensors are then adjusted for the particular flow
stream to the desired flow rate as measured with the reference flow meter. The
span adjustments are set with RP3 and RP2, for hydrogen and oxidant
respectively, so that the display on the controller matches the value obtained
with the reference flow meter. Upon completion, remove the reference flow
meter and return the bypass jumper (JP1) to its original position.
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Detector Sensitivity
Detector sensitivity is an indicator reflecting the performance characteristics
of a given system, and is a useful tool to determine when Detector
maintenance is warranted. Sensitivity is typically reported as a minimum
detection limit (MDL) as calculated from the following formula:
0.66×(Am'tN / S)×(PktoPkNoise)
MDL =
(Wd
)×(Signal)
1/2ht
Where Am't N/S (amount of nitrogen or sulfur) is the mass of nitrogen or
sulfur in picograms that reaches the Detector, PktoPkNoise (peak-to-peak
noise) is the measure of the noise (e.g. in mV), Signal is the height of the peak
in the same units, and Wd1/2ht is the width of the peak at half height in
seconds. The constant 0.66 is used in the calculation assuming the MDL S/N =
3.29.
Before it is released from the factory, each 355 SCD must pass an MDL level of
<0.5 pg Sulfur/second and each 255 NCD must pass an MDL level of <3.0 pg
Nitrogen/second. The response from individual detection systems may vary by
a factor of 2 or 3; however, it is typical for Detectors to perform in the 0.1-0.3
pg S/second range for the 355 SCD and in the 1-2 pg N/second for the 255 NCD
when tested at Agilent.
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Assembling the Dual Plasma Burner for Component Replacement with the
SCD
The following procedure can be used to assemble the Dual Plasma Burner for
use with the SCD or for replacement of Burner components, such as ceramic
1 Slide the 0.066" internal diameter (I.D.) double taper ferrule onto the lower
Burner tube. The tube should extend approximately 2 mm past the end of
the ferrule.
2 Insert the lower Burner tube and double taper ferrule into the Burner inlet
fitting.
3 Slide the 1/4" Burner adapter over the top of the lower Burner tube all the
way down to the Burner inlet fitting and screw it onto the fitting
finger-tight.
Figure 25 Ferrule Placement on Lower Burner Tube
4 Slide a 1/4" Swagelok nut over the Burner adapter and then slide a 1/4"
ferrule over the Burner adapter and position it into the 1/4" nut. Note: If a
graphite ferrule is used, a small amount of shavings may be created and
some graphite will be left on the tube surface; this is normal. Avoid allowing
any shavings to fall inside a tube.
5 Center the lower Burner tube so that it will slide into the tapered union.
Insert the lower end of the tapered union fitting into the 1/4" Swagelok nut
and screw it on finger-tight. If necessary, the brazed H line can be gently
2
bent out of the way, however, be careful not to stress the brazed (welded)
connection.
6 Insert the large ceramic tube into the quartz heater assembly. Position a
1/4" ferrule (flat end butted up against the top of the swivel nut) onto the
large ceramic tube. With the ferrule positioned against the swivel nut,
approximately 0.5 cm of the large ceramic tube should extend outside of the
nut. Insert the lower Burner tube into the center of the large ceramic tube
and finger tighten the heater swivel nut onto the tapered union fitting.
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Figure 26 Proper Ferrule Orientation to the Large Ceramic Tube
Figure 27 Large Ceramic Tube Properly Inserted into the Quartz Heater Assembly
7 Position the upper ceramic tube into the long axis of the splitter fitting so
that about 4 mm of it extends past the top of the fitting. Slide the 0.054" ID
double tapered ferrule over the upper ceramic tube. Gently holding these
parts so that neither the ferrule nor the upper ceramic tube slips out of
position, finger-tighten the union fitting onto the splitter fitting.
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Figure 28 Orientation of the Double Taper Ferrule
Figure 29 Positioning the Upper Tube in the Union Fitting
8 Approximately 1.5 cm of the large ceramic tube should extend above the top
of the quartz heater assembly. Slide a 1/4" Swagelok nut over the large
ceramic tube and then also slide a 1/4" ferrule over the tube (flat side on
back of the nut).
9 Holding the splitter fitting, gently insert the upper ceramic tube into the
large ceramic tube coaxially, to avoid placing stress on the fragile upper
ceramic tube. Lower the splitter fitting into place to engage the threads of
the 1/4" Swagelok nut. Tighten finger-tight.
10 To begin the final alignment and tightening, use a 7/16" wrench and 5/16"
wrench to tighten the 1/4" Burner adapter one-quarter turn past
finger-tight.
11 Using a 5/8" wrench on the heater swivel nut and a 1/2" wrench on one of
the flats of the tapered union fitting, tighten the heater swivel nut
one-quarter turn past finger-tight. Using a 5/16" wrench on the 1/4" Burner
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adapter, rotate this fitting so that the brazed H line is aligned 180 °
2
(opposite) from the oxidizer Inlet port.
Figure 30 Tightening the Heater Swivel Nut
12 Making sure that the Burner inlet fitting does not loosen, use a 1/2" wrench
on a flat of the tapered union fitting and 9/16" wrench on the 1/4" Swagelok
nut of the Burner adapter to tighten the tapered union fitting 1/4" past
finger-tight.
13 Rotate the quartz heater assembly so that the thermocouple and heater
leads are in the same plane and pointed in the same direction as the peg on
the Burner inlet fitting. Turn the splitter fitting so that H2 inlet port is also
aligned with the peg on the Burner inlet fitting.
Figure 31 Proper Alignment of the Burner
14 Tighten the nut on the splitter fitting one-quarter turn past finger-tight
using a 9/16" wrench on the 1/4" nut and a 7/16" wrench on the flats of the
splitter fitting.
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15 Carefully bend the H line into position so that the 1/16" Valco nut and
2
ferrule can be screwed into the side port of the splitter fitting. Tighten the
connection of the H line to the splitter fitting using a 3/8" wrench on the
2
vertical flat of the splitter fitting and 1/4" wrench on the Valco nut.
16 Make sure that no other connections have loosened or moved out of
alignment, if so, reposition or retighten the fittings as needed.
17 The assembled Burner is now ready for re-installation on the GC.
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Assembling the Dual Plasma Burner for Component Replacement with the
NCD
The following procedure can be used to assemble the Dual Plasma Burner for
use with the NCD or for replacement of Burner components, such as ceramic
lower section of the NCD Burner is identical to the lower section of the SCD
Burner.
While the use of 1/4" ferrules is optional with the SCD, the quartz tube used in the NCD
NOTE
Burner is more fragile and the use of 1/4" graphite ferrules is highly recommended.
1 Slide the 0.066" internal diameter (I.D.) double taper ferrule onto the lower
Burner tube. The tube should extend approximately 2 mm past the end of
the ferrule.
2 Insert the lower Burner tube and double taper ferrule into the Burner inlet
fitting.
3 Slide the 1/4" Burner adapter over the top of the lower Burner tube all the
way down to the Burner inlet fitting and screw it onto the fitting
finger-tight.
Figure 32 Ferrule Placement on Lower Burner Tube
4 Slide a 1/4" Swagelok nut over the Burner adapter and then slide a 1/4"
ferrule over the Burner adapter and position it into the 1/4" nut.
5 Center the lower Burner tube so that it will slide into the tapered union.
Insert the lower end of the tapered union fitting into the 1/4" Swagelok nut
and screw it on finger-tight. If necessary, the brazed H line can be gently
2
bent out of the way. Be careful not to stress the brazed (welded) connection.
6 Find the quartz combustion tube, 1/4" ferrule and quartz heater assembly.
7 Insert the quartz tube into the quartz heater assembly. Position a 1/4"
ferrule (flat end butted up against the top of the swivel nut) onto the quartz
combustion tube. With the ferrule positioned against the swivel nut,
approximately 0.5 cm of the quartz tube should extend outside the nut.
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Figure 33 Proper Ferrule Orientation to the Large Quartz Tube
Figure 34 The Quartz Tube Properly Inserted into the Quartz Heater Assembly
8 Insert the lower burner tube into the center of the quartz tube and finger
tighten the heater swivel nut onto the tapered union fitting, then tighten an
additional 1/4 turn making sure not to break the quartz tube.
9 To begin the final tightening, use a 7/16" wrench and 5/16" wrench to
tighten the 1/4" Burner adapter one-quarter turn past finger-tight.
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10 Using a 5/8" wrench on the heater swivel nut and a 1/2" wrench on one of
the flats of the tapered union fitting, tighten the heater swivel nut
one-quarter turn past finger-tight. Using a 5/16" wrench on the ¼" Burner
adapter, rotate this fitting so that the brazed H line is aligned 180 °
2
(opposite) from the oxidizer Inlet port.
11 Making sure that the Burner inlet fitting does not loosen, use a 1/2" wrench
on a flat of the tapered union fitting and 9/16" wrench on the 1/4" Swagelok
nut of the Burner adapter to tighten the tapered union fitting 1/4" past
finger-tight.
12 Rotate the quartz heater assembly so that the thermocouple and heater
leads are in the same plane and pointed in the same direction as the peg on
the Burner inlet fitting. Turn the splitter fitting so that H inlet port is also
2
aligned with the peg on the Burner inlet fitting.
Figure 35 Burner Assembly Detail
Figure 36 Burner Assembly Alignment
13 The assembled Burner is now ready for re-installation on the GC.
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Tube Replacement for the SCD
The Burner has two combustion tubes that require replacement: the upper
ceramic tube and the Large Ceramic Tube. Generally the tubes should be
replaced only if sensitivity decreases. The “Troubleshooting” chapter provides
additional information to assist in determining whether tube replacement may
Follow the instructions below for tube replacement.
1 Turn off power to the GC and the Controller and let the system cool down
under vacuum.
2 Turn off power to the vacuum pump.
3 Lift the Burner out of the shroud. It is recommended to remove the coil,
noting the position of the ferrule. In some instances, if the coil can be
uncoiled, it may be convenient to leave it attached to the Burner.
4 Disconnect the hydrogen and oxidant lines.
5 Disconnect the power connector that leads to the GC, if necessary.
6 Tilt the Burner at an angle, so that when loosening the union fitting the
upper ceramic tube does not slide down into the large ceramic tube.
7 Loosen and disconnect the union fitting, and pull the splitter fitting and
upper ceramic tube out of the Burner.
8 Slide the upper ceramic tube out of the splitter fitting.
9 Slide the upper ceramic tube into the splitter fitting, so that approximately
4 mm of the tube extends beyond the top of the fitting. Then, slide the
positioning). Gently holding these parts so that neither the ferrule nor the
upper ceramic tube slip out of position, finger-tighten the union fitting onto
the splitter fitting.
Figure 37 Orientation of the Double Taper Ferrule
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Figure 38 Positioning the Upper Tube in the Union Fitting
10 Holding the splitter fitting, gently insert the upper ceramic tube into the
large ceramic tube coaxially, to avoid placing stress on the fragile upper
ceramic tube. Lower the splitter fitting into place to engage the threads of
the 1/4" Swagelok nut. Tighten finger-tight.
12 Remove the Tapered Union Fitting from the bottom of the Burner.
13 Slide the Large Ceramic Tube out of the Burner and remove it from the
Quartz Heater Assembly.
14 Insert the new large ceramic tube into the quartz heater assembly. Position
a 1/4" ferrule (flat end butted up against the top of the swivel nut) onto the
large ceramic tube. With the ferrule positioned against the swivel nut,
approximately 0.5 cm of the large ceramic tube should extend outside of the
nut. Insert the lower Burner tube into the center of the large ceramic tube
and finger tighten the heater swivel nut onto the tapered union fitting.
Figure 39 Proper Ferrule Orientation to the Large Ceramic Tube
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Figure 40 Large Ceramic Tube Properly Inserted into the Quartz Heater Assembly
15 Approximately 1.5 cm of the large ceramic tube should extend above the top
of the quartz heater assembly. Slide a 1/4" Swagelok nut over the large
ceramic tube and then also slide a 1/4" ferrule over the tube (flat side on
back of the nut).
16 To begin the final alignment and tightening, use a 7/16" wrench and 5/16"
wrench to tighten the 1/4" Burner adapter one-quarter turn past
finger-tight.
17 Using a 5/8" wrench on the heater swivel nut and a 1/2" wrench on one of
the flats of the tapered union fitting, tighten the heater swivel nut
one-quarter turn past finger-tight. Using a 5/16" wrench on the 1/4" Burner
adapter, rotate this fitting so that the brazed H line is aligned 180 °
2
(opposite) from the oxidizer Inlet port.
Figure 41 Tightening the Heater Swivel Nut
18 Making sure that the Burner inlet fitting does not loosen, use a 1/2" wrench
on a flat of the tapered union fitting and 9/16" wrench on the 1/4" Swagelok
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nut of the Burner adapter to tighten the tapered union fitting one-quarter
turn past finger-tight.
19 Rotate the quartz heater assembly so that the thermocouple and heater
leads are in the same plane and pointed in the same direction as the peg on
the Burner inlet fitting. Turn the splitter fitting so that H inlet port is also
2
aligned with the peg on the Burner inlet fitting.
Figure 42 Proper Alignment of the Burner
20 Tighten the nut on the splitter fitting one-quarter turn past finger-tight
using a 9/16" wrench on the 1/4" nut and a 7/16" wrench on the flats of the
splitter fitting.
21 Carefully bend the H line into position so that the 1/16" Valco nut and
2
ferrule can be screwed into the side port of the splitter fitting. Tighten the
connection of the H line to the splitter fitting using a 3/8" wrench on the
2
vertical flat of the splitter fitting and 1/4" wrench on the Valco nut.
22 Make sure that no connections have loosened or moved out of alignment, if
so, reposition or retighten the fittings as needed.
23 Replace the Burner in the shroud.
24 Follow the standard system start-up procedure, including column
placement.
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Tube Replacement for the NCD
The Burner has one quartz combustion tube that requires replacement.
Generally the tube should be replaced only if sensitivity decreases. The
“Troubleshooting” chapter provides additional information to assist in
page 46 for proper part nomenclature. Follow the instructions below for tube
replacement.
1 Turn off power to the GC and the Controller and let the system cool down
under vacuum.
2 Turn off power to the vacuum pump.
3 Lift the Burner out of the shroud. It is recommended to remove the coil,
noting the position of the ferrule. In some instances, if the coil can be
uncoiled, it may be convenient to leave it attached to the Burner.
4 Disconnect the hydrogen and oxidant lines.
5 Disconnect the power connector that leads to the GC, if necessary.
6 Loosen and disconnect the union fitting from the top of the Burner.
7 Remove the tapered union fitting from the bottom of the Burner.
8 Slide the large quartz tube out of the Burner and remove it from the quartz
heater assembly.
9 Insert the new quartz tube into the quartz heater assembly. Position a 1/4"
ferrule (flat end butted up against the top of the swivel nut) onto the quartz
combustion tube. With the ferrule positioned against the swivel nut,
approximately 0.5 cm of the quartz tube should extend outside the nut.
Figure 43 Proper Ferrule Orientation to the Large Quartz Tube
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Figure 44 Large Quartz Tube Properly Inserted into the Quartz Heater Assembly
10 Insert the lower burner tube into the center of the quartz tube and finger
tighten the heater swivel nut onto the tapered union fitting, then tighten an
additional 1/4 turn making sure not to break the quartz tube.
11 To begin the final tightening, use a 7/16" wrench and 5/16" wrench to
tighten the 1/4" Burner adapter one-quarter turn past finger-tight.
12 Using a 5/8" wrench on the heater swivel nut and a 1/2" wrench on one of
the flats of the tapered union fitting, tighten the heater swivel nut
one-quarter turn past finger-tight. Using a 5/16" wrench on the ¼" Burner
adapter, rotate this fitting so that the brazed H line is aligned 180º
2
(opposite) from the oxidizer Inlet port.
13 Making sure that the Burner inlet fitting does not loosen, use a 1/2" wrench
on a flat of the tapered union fitting and 9/16" wrench on the 1/4" Swagelok
nut of the Burner adapter to tighten the tapered union fitting one-quarter
turn past finger-tight.
14 Rotate the quartz heater assembly so that the thermocouple and heater
leads are in the same plane and pointed in the same direction as the peg on
the Burner inlet fitting. Turn the splitter fitting so that H inlet port is also
2
aligned with the peg on the Burner inlet fitting.
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Solving Detector Problems
A basic understanding of the Detector helps one systematically diagnose and
solve Detector problems. Many symptoms may be caused by more than one
problem and these are the most difficult to troubleshoot. It should be pointed
out, however, that analysis of sulfur or nitrogen compounds has traditionally
been very difficult because of the inherent reactivity and instability of the
compounds themselves. Often, problems blamed on the Detector actually
originate from either poor chromatographic technique or other system failures
(most of these problems are injector related).
Therefore, the first step in troubleshooting is to isolate the problem: in the
chromatographic system, the Burner assembly, or in the Detector itself (ozone
generator, vacuum pump, photomultiplier tube or electronics). Diagnosing the
attempting to verify initial conditions. The table at the end of this section lists
many common problems, their most probable causes and corrective action that
should be taken.
to aid troubleshooting. in the maintenance log, keep track of detector flow
rates (oxidizer and hydrogen), pressures (burner controller and reaction cell
in detector), and background signal (the difference between ozone “on” and
ozone “off”).
For assistance with troubleshooting Detector problems, contact Agilent with
the serial number of the unit, the conditions used by the instrument, and any
recent changes that have been made.
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Power Problems
The first step in the determination of a power related problem is to verify
power to the pump, Controller, and Detector itself. The inability to establish
power may be as trivial as a blown fuse. Fuse requirements and positions on
Repeated fuse failure is an indication of a more serious situation.
Detector Fuse
If the Standby LED does not illuminate when the unit is plugged in, and
multiple fuses fail on the Detector, disconnect the power cord and contact
Agilent.
Vacuum Pump Fuse
Repeated blown fuses of the vacuum pump indicate a pump oil problem. If the
vacuum pump has not been in operation for some time or if water accumulated
in the vacuum pump has not been properly removed, the pump may be difficult
to start, or may require more power than normal, and this may blow the main
AC fuse. Disconnect the main power cord from the AC outlet and from the back
panel of the Detector. Replace the pump oil. Connect the pump power cord to
an AC outlet in the lab to start it. Allow the pump to operate for 10 to
15 minutes, after which the pump may be plugged back into the rear panel of
the Detector. If fuses blow after the pump oil has been changed, the pump has
been damaged. Contact Agilent for further information.
The dry piston pump may require a short break-in time when new or after
seals have been changed. It can be operated for a few hours by plugging it into
a wall outlet. When turned off, it is necessary to allow the pump pressure to
reach atmospheric conditions before restarting.
Also note that the dry piston pump is equipped with a thermal fuse;
connecting the pump to a power supply that exceeds 110 V 10% will result in
the pump shutting down.
Dual Plasma Controller Fuses
If the Controller will not power on, confirm that the power cord is firmly
seated at both ends. Also make certain that there is power to the outlet at the
wall, surge protector, or circuit breaker. If the power cord is seated correctly
and power is available to the Controller, the fuse in the power entry module
(just above the power switch) on the back of the Controller may have blown.
Make sure that the actual line voltage and the setting on the Controller match.
To replace the fuse in the power entry module, follow these steps:
1 Unplug the power cord from the back of the Controller.
2 Use a small flat-head screwdriver to pry open the fuse cover on the power
entry module on the back of the Controller.
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3 Remove the old fuses from the holder and replace with new fuses.
If the Controller still does not power on after replacing the fuse, contact
Agilent.
Table 4 Fuses for 100 V, 120 V and 230 V Versions of 355 SCD and 255 NCD
100/120 V
230 V
Detector Back Panel
Main AC Power
15 A/250 V
3AG slo-blo
T10 A/250 V
5 x 20mm
Detector
Electronics Power Supply (F1) 250 mA/250 V
3AG slo-blo
T125 mA/250 V
5 x 20mm
Pump (F2)
15 A/250 V
3AG slo-blo
T5 A/250 V
5 x 20mm
Ozone Generator (F3)
Photomultiplier Tube Cooler
1 A/250 V
3AG slo-blo
T100 mA/250 V
5 x 20mm
1 A/250V
3AG slo-blo
T500 mA/250V
5 x 20mm
Dual Plasma Controller Back Panel
Main AC Power (2 fuses) T2 A/250 V
1 A/250 V
5 x 20mm
5 x 20mm
F1
ELECTRONICS
OZONE
ELECTRONICS
T125 mA
OZONE
F3
F2
T100 mA
PUMP
PUMP
T5 A
Front View (230 V Unit)
Side View
Figure 47 Fuse Positions on the Power Supply Board
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Ozone Generation Problems
Following the verification of power to the instrumental components, the next
step in tracing a problem is the determination of ozone production. With the
ozone toggle off and the vacuum pump on, read the signal output on the front
of the Detector. Toggle the ozone on. A properly operating Detector will
typically display a difference in background of 0.2 to 2 mV. If no change is
observed, a problem most likely lies within the ozone generator itself, the high
voltage transformer supplying power to the ozone generator, or in the transfer
line system between the ozone generator and the reaction cell.
Ozone Generator
Loss of ozone from the ozone generator may arise from generator fault, or from
a leak in the corona discharge tube. Typically a pungent ozone odor will be
noticed emanating from the side of the Detector if the ozone generator is
leaking.
Any operation requiring access to the inside of the equipment, could result in injury. To
avoid potentially dangerous shock, disconnect from power supply before opening the
equipment.
WARNING
WARNING
High voltages supply the ozone generator. Unplug the instrument.
Removal of the left side panel (as seen from the front of the Detector) and
removal of the ozone generator cover panel may reveal corrosion caused by
escaped ozone. If this is the case, replace the ozone generator. Resistance
across the leads to the ozone generator should be infinite. Measure the
resistance with an ohmmeter to verify. If there is a resistance, replace the
ozone generator.
High Voltage Transformer
The high voltage transformer produces 6000 - 8000 volts.
WARNING
The following test should only be performed by those with high voltage experience using
high voltage probes.
Using high voltage probes, directly measure the secondary output of the ozone
generator. A properly functioning generator will produce approximately
7500 volts. Output less than 3000 volts mandates replacement of the high
voltage transformer.
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Plugged Restrictor Lines
Plugged restrictor lines are verified by turning off the air/oxygen regulator
located inside the door of the Detector and observing little or no change in the
pressure as indicated on the regulator. The plug can be located in either the
plugged restrictor line can result in a non-linear signal, or reduced sensitivity
which will vary with the flow of ozone. Replace the restrictor lines.
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Response Problems
Low or no response problems are the most difficult to troubleshoot on the
Agilent SCD and NCD as they may arise from one source or a combination of
sources. Primarily, response problems are due to combustion problems, and
Burner integrity should be investigated first.
It is beyond the scope of this supplement to deal with all possible
chromatography related problems. The following table lists many of the
common problems, their most probable causes, and the corrective action that
should be taken. For further assistance contact Agilent.
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Temperature Reading Problems
Normally, the controller displays the burner temperature set-point. For
diagnostic purposes, a switch in the controller (JP2) can be positioned to allow
the display of the actual thermocouple temperature reading. When the actual
temperature and set-point temperature agree, the heater indicator light on the
front of the controller is illuminated. Note that there is a slight offset between
these readings.
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Diagnosing General Problems
Table 5 Troubleshooting Detector Issues
Problem
Possible Cause
Diagnosis
Corrective Action
No Response
No ozone
Little or no difference in
Continue below. See No
output signal between ozone Ozone in Problem column.
ON vs. OFF. Typically the
background signal will be
0.3-0.8 mV higher with the
ozone ON.
No Ozone
No Ozone
Blown fuse
Ozone indicator light
remains off when ozone
button is pushed.
Replace ozone fuse.
High Voltage Transformer
and/or ozone generator is
inoperative.
No difference in output
Have ONLY someone with
signal between ozone ON vs. high voltage experience use
OFF even though flow a high voltage probe to
through the ozone generator check the input to the ozone
is good (about
25-35 mL/min).
generator across the two
wires. It should be
>6000 volts. If it is not then
replace high voltage
transformer. If it is, replace
ozone generator.
No Ozone
Ozone restrictor(s) plugged. Needle on the regulator
inside front panel does not
move downward when
Replace plugged
restrictor(s).
regulator is turned fully
counterclockwise. The
measured flow is low or
non-existent.
No Response
No Response
Hydrogen and/or air ran out. Measure flow rates.
Set correctly.
Change tubes.
Broken ceramic tube(s).
Pressure on Controller
and/or Detector is too high
or too low.
No Response
Low Response
Low Response
Heating element failure.
Temperature at Controller
<100 °C.
Replace heating element.
Adjust flow rates.
Improper hydrogen/air flow Measure flow rates.
rates.
Detector leaks.
Note pressures on
Controller.
Locate and repair leaks,
check integrity of ferrules.
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Table 5 Troubleshooting Detector Issues (continued)
Problem
Possible Cause
Diagnosis
Corrective Action
Low Response
Contaminated ceramic
tubes.
If there does not appear to
be a leak, then the tubes
should be inspected.
Replace tubes.
Contamination can result
from column bleed, samples
which may contain volatile
metal complexes, and large
injections of coke forming
hydrocarbons.
Wandering Baseline
Wandering Baseline
Wandering Baseline
Poor temperature control.
Monitor the temperature on Check for a loose connection
the Controller. It should vary on the heating element or
by no more than 5 °C.
thermocouple. Reposition
the thermocouple in the
Burner.
Contamination in one of the Check the difference in the
Detector gases.
Change Detector gases after
output signal between ozone adding in-line traps.
on and off. The difference
should be between 0.2-2 mV
after equilibration.
Leak in the oxidizer line at
If using SCD, use a microliter Reseat air line into air inlet
the oxidizer inlet connection. syringe containing a small
amount of sulfur compound
nut, or replace.
e.g., CS2 to “snoop” for leaks
while watching mV output.
Leaks are very evident by a
large increase in signal
displayed on the LED.
Leak at weld of H2 inlet
fitting.
Tailing Peaks with
Non-Equimolar Response
Severe contamination of
Detector gases.
High background signal with Avoid “house” gases,
respect to ozone off.
especially air from
compressors. Clean gases
should be used with
appropriate traps.
Tailing Peaks
Poor column connection.
Verify column position at
inlet and outlet. Look for
discoloration of column at
Detector side which
Reinstall column.
indicates column in
combustion zone.
Tailing Peaks
Cracked tubes.
Confirm pressure and
vacuum ranges. Inspect
columns and ferrules.
Replace tubes as needed.
Replace thermocouple.
Controller Reads >1000 °C
Thermocouple open.
Check electrical resistance
between thermocouple pins.
114
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Table 5 Troubleshooting Detector Issues (continued)
Problem Possible Cause
Diagnosis
Corrective Action
Burner Fault Cycles. (off and Cracked tube.
ON)
Pressure increases
>525 torr, Burner faults.
Cycle repeated as
temperature and pressure
reset.
Replace broken tubes.
Burner Fault Cycles (off and Leak in Burner.
ON)
Pressure increases
>600 torr, Burner faults.
Cycle repeated as
temperature and pressure
reset.
Locate and repair leaks,
check integrity of ferrules.
Table 6 Troubleshooting Pump Issues
Problem
Possible Cause
Diagnosis
Corrective Action
Pump is noisy
High-pressure dry piston.
Pressure in the reaction cell Change sleeve/seal.
is unacceptably high and the
pump is getting audibly
noisy.
Pump Doesn’t Start
Pump Doesn't Start
Fuses Blow on Startup
Water in Pump
Dry piston seals have
recently been changed.
Pump fuses blow
immediately after changing time of a few minutes after
the seals and sleeves.
Dry piston requires break-in
seals are changed.
Pump switch off (dry piston Locate pump switch on
pump must start from
atmospheric pressure).
Turn ON switch.
pump and verify position.
Inspect oil for integrity.
Emulsified oil (worn seals
and head on dry piston
pump).
Change pump oil, and plug
unit into wall to run for 10-15
minutes.
Cracked coalescing filter.
Milky yellow oil in the pump Change coalescing filter and
window.
pump oil.
Reaction Cell Pressure High chemical trap clogged.
Reaction Cell Pressure High Leak in ozone generator.
Remove trap from the
vacuum line and confirm
expected pressure readings.
Change chemical trap.
Air regulator falls rapidly to
zero when turned off.
Replace ozone generator.
Pump Loses Oil
Gurgle Sound
Ballast Open.
Oil level drops.
Reset ballast
See Pump specific sections.
High level of oil in
Coalescing Filter
Plugged oil return restrictor No visible movement of oil in Change filter and clear
the return line. restrictor.
Operation and Maintenance Manual
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Table 7 Troubleshooting Burner Issues
Problem
Possible Cause
Diagnosis
Corrective Action
Fuses Blow on Startup
Shorted heater element.
Inspect for exposed wires or Take Burner top off and
broken insulation around
wire leads. Measure
resistance leads, should not
be 0.
reseat insulation around
heater leads.
Low Sensitivity
Leaks at ferrules or fittings. For SCD, use a microliter
syringe containing a small
Inspect fittings for scoring
and replace if necessary.
amount of sulfur compound Replace ferrules if worn.
e.g., CS2 to “snoop” for leaks Hand tighten all fittings
while watching mV output.
Leaks are very evident by a
large increase in signal
displayed on the LED.
mounted onto vespel
ferrules, and wrench tighten
all connections with Valco
ferrules.
For NCD, a high background
could be observed from
atmospheric nitrogen.
Low Sensitivity
Low Sensitivity
Improper gas flows.
Measure gas flows.
Reset gas flows.
Broken ceramic tubes or
ferrules
Remove and inspect tubes
and ferrules for chips and/or
breaks.
Replace tubes or ferrules.
High Pressure
Low Sensitivity
Improper column
positioning.
Inspect for charred Detector After cutting off charred end
end of column.
of column, measure column
length 108-109 mm from
ferrule (or 114-115 mm from
bottom of nut) and re-attach
column.
High Background
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Index
Fuses
C
S
Schematic
I
Sensitivity
Installation
D
Signal Output Cables
Detector
Special Operating Modes
Dry Piston Pump
Dual Plasma Burner
T
M
Temperature
Troubleshooting
Maintenance
Dual Plasma Controller
O
Ozone Generator
Tube Replacement
P
E
V
Edwards oil-sealed pump
Vacuum Pump
Q
W
F
Welch Dry Piston Pump
R
FID Adapter
Operation and Maintenance Manual
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Agilent Technologies
© Agilent Technologies, Inc.
Printed in USA, June 2007
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