VICI D-2-IM User Manual
Valco Instruments Co. Inc.
Pulsed Discharge
Detector
Model D-2-IM
Instruction Manual
Valco Instruments Co. Inc.
800
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688
·
688
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9345 tech
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8106 fax
713
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valco@vici.com
Valco International
Schenkon, Switzerland
Int + 41 · 41 · 925
Int + 41 · 41 · 925
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D2-IM.p65
©2011 9/11
Printed in USA
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Table of Contents
Introduction
System Requirements
Installation
Description and Operating Principles .......................................................................................... 1
Safety Notes and Information ................................................................................................... ...... 2
Symbols
Installation Category
Safety
Maintenance
Components of the Detector System .......................................................................................... 4
Description of Controls ..................................................................................................................... 4
Components Not Included with the Detector System .......................................................... 8
System Purity ........................................................................................................................................ 8
Specifications ....................................................................................................................................... 9
Purity Specifications ........................................................................................................................... 9
GC Column Selection ..................................................................................................................... 10
General Precautions ........................................................................................................................ 11
Mounting the Detector on the GC ............................................................................................. 11
Gas Connections .............................................................................................................................. 12
Installing and Purging the Gas Regulator ....................................................................... 12
Installing and Purging the Helium Purifier .................................................................... 13
Connecting the Discharge Gas to the Detector .......................................................... 14
Column Connection ........................................................................................................................ 14
Testing for Leaks ............................................................................................................................... 14
Electrical Connections .................................................................................................................... 15
Initial Power-Up ................................................................................................................................16
Troubleshooting High Background Current ............................................................................. 17
Checking for Leaks in the Discharge Gas Plumbing .................................................. 17
Column Bakeout Precautions ........................................................................................... 17
Warranty ..................................................................................................................................................... 18
Detector Performance Log .................................................................................................................... 19
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Introduction
Description and Operating Principle
1
The pulsed discharge detector Model D-2-IM is a universal helium photoionization
detector optimized for trace level work with micropacked and capillary columns.
A schematic representation is shown in Figure 1.
As the name implies, a stable, low power, pulsed DC discharge in helium is utilized
as the ionization source. Elutants from the column, flowing counter to the flow of
helium from the discharge zone, are ionized by photons from the helium discharge
above. Resulting electrons are focused toward the collector electrode by the two
bias electrodes.
The principal mode of ionization is photoionization by radiation arising from the
transition of diatomic helium
This is the well-known Hopfield emission. The photon energy from the He
He
1
+
(
∑
)
A
u
2
to the dissociative 2He(1S
1
) ground state.
2
continuum is in the range of 13.5 eV to 17.7 eV.
The PDHID is essentially non-destructive (0.01 - 0.1% ionization) and highly
sensitive. The response to organic compounds is linear over five orders of
magnitude with minimum detectable quantities (MDQs) in the low or sub
picogram range. The response to fixed gases is positive (the standing current
increases), with MDQs in the low ppb range.
HELIUM INLET
DISCHARGE ZONE
SPRING WASHERS
DISCHARGE ELECTRODE
QUARTZ
GROUND
BIAS ELECTRODE
COLLECTOR ELECTRODE
BIAS ELECTRODE
INSULATOR
SAPPHIRE
INSULATORS
CAPILLARY COLUMN
VENT
COLUMN INLET
Figure 1: Schematic of the D-2-IM detector
Introduction
2
The PDHID response is universal except for neon, which has an ionization potential
of 21.56 eV. Since this potential is close to the energy of the He* metastable
(19.8 eV ) but greater than the photon energy from the He2 continuum, neon
exhibits a low ionization efficiency and low detector response. (NOTE: Valco
makes an enhanced mode detector for neon. Consult the factory for information.)
Safety Notes and Information
Symbols
HIGH VOLTAGE
Voltages presenting the risk of electric shock are present in several
places in the equipment. Avoid contact with hazardous live parts.
Do not probe into openings or attempt to defeat safety mechanisms.
HOT SURFACE
The surface of the detector body may be hot while in operation
(possibly in excess of 250°C). Caution should be observed.
ATTENTION
Refer to the manual.
PROTECTIVE EARTH
This internal connection provides protection against electric shock
from mains voltages and should not be removed.
Installation Category
This equipment has been designed for installation category (overvoltage category)
II, pollution degree 2. It has been approved for use only in heavy industrial environments and may not be used in the residential, commercial, or light-industrial
environment.
Introduction
Safety
This instrument has been designed and tested in accordance with the product
safety standard, EN61010. It has left the factory in a safe condition. This instruction
manual contains important information and warnings which must be followed by
the user to insure safe operation and to retain the instrument in a safe condition.
The case, chassis, and measuring terminals are connected to the protective earth
contact of the mains inlet. The instrument operates with a three-conductor power
cord having a protective earthing conductor and a plug with an earthing contact.
The mains (line) plug shall only be inserted in a socket outlet provided with a
protective earth contact. The protective action must not be negated by the use
of an extension cord without a protective conductor. Use only with an approved
mains supply cord having a rating of 2A, 250V, or greater. Do not use this equipment in a manner not specified herein.
CAUTION: During normal operation, the detector produces
ultraviolet energy (UVA, UVB), some of which may be
emitted. Do not watch the arc without eye protection.
3
Maintenance
The exterior of the instrument should be cleaned regularly with a dusting brush. If
necessary, the casing can be cleaned with a moistened cloth (99% water + 1% mild
detergent). Spirit or petroleum ether can be used to remove greasy dirt. Any other
cleaning agents can attack the plastic and painted surfaces.
Under no circumstances should the cleaning fluid get into the instrument.
Petroleum ether is flammable, and care should be taken in its use. Under no
circumstances should the detector be disassembled for cleaning. The components
of the detector are assembled with special tooling and held under considerable
force. Disassembly of the detector may present a safety hazard and will result in
its destruction.
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