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d4_var.P65

Rev 5/12

Printed in USA

Pulsed Discharge

Detector

Model D-4-I-VA38-R

Instruction Manual

Introduction

Description and Operating Principles............................................................1

Safety Notes and Information........................................................................2

Symbols

Installation Category

Safety

Components of the Detector System............................................................3

System Requirements

Components not Included with the Detector System....................................4

System Purity................................................................................................4

Gas Specifications........................................................................................5

Installation

General Precautions......................................................................................6

Mounting the Detector on the GC.................................................................6

Gas Connections...........................................................................................7

Installing and Purging the Gas Regulator..............................................7

Installing and Purging the Helium Purifier..............................................8

Connecting the Discharge Gas to the Detector.....................................8

Capillary Column Connection........................................................................9

Packed Column Connection..........................................................................9

Testing for Leaks.........................................................................................10

Pulser Module Installation...........................................................................11

Detector Electrical Connections..................................................................12

Initial Power-Up...........................................................................................13

Troubleshooting High Background Current..................................................13

Mode Selection and Setup

Helium Ionization Mode...............................................................................14

Selective Photoionization Mode...................................................................14

Warranty............................................................................................................16

Summary of content (18 pages)

PAGE 1
Valco Instruments Co. Inc. Pulsed Discharge Detector Model D-4-I-VA38-R Instruction Manual Introduction Description and Operating Principles ............................................................ 1 Safety Notes and Information ........................................................................ 2 Symbols Installation Category Safety Components of the Detector System ............................................................
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1 Introduction Description and Operating Principle The PD-D-4-I-VA38-R is a non-radioactive pulsed discharge ionization detector (PDID) which is optimized for the Varian 3800 GC. A schematic representation of the basic D4 detector is shown in Figure 1. The D4 utilizes a stable, low power, pulsed DC discharge in helium 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.
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Introduction 2 Helium Ionization (PDHID) 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. The PDHID response is universal except for neon, which has an ionization potential of 21.56 eV.
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Introduction 3 Components of the Detector System Components of the detector system are listed in the Table 1. Check the contents of the packages to verify that everything is present. Contact the factory if anything is missing or damaged. (NOTE: damaged shipments must remain with the original packaging for freight company inspection.) Table 2 lists additional required items which must be purchased from Varian.
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Introduction 4 System Requirements Components Not Included with the Detector System • Helium (99.
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Introduction 5 Gas Specifications Detector Mode PDHID Ar-PDPID Discharge gas Helium 2% Ar in He Carrier gas Helium * Kr-PDPID Xe-PDPID 1.5% Kr in He 0.8% Xe in He ** ** ** Any gas including He which has an ionization potential greater than 12 eV ** Any gas including He which has an ionization potential greater than 11 eV Purity Specifications • Helium (discharge and carrier gas) must have a minimum purity of 99.999%, with < 20 ppm Ne impurity.
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6 Installation General Precautions • Do not use plastic/polymer or copper tubes for gas handling and interconnectons. Use only stainless steel tubing with Valco gold-plated ferrules. • Do not turn the unit on until helium discharge gas is flowing through the detector. • Do not shut off or disconnect the discharge gas when the detector is hot, even if the unit is turned off.
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Installation 7 Gas Connections Remember these three points discussed earlier: (1) all surfaces that contact the gas stream must be fused silica or stainless steel; (2) do not use copper tubing or brass fittings; and (3) all tubes must be thoroughly cleaned and baked before use. The installation instructions below assume that the detector discharge gas will be supplied from a nearby cylinder of helium of the proper purity.
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Installation 8 7. Open the cylinder valve to pressurize the regulator once again. Close the valve and observe the needle of the high pressure gauge for 15 minutes. If it doesn’t move, there is no critical leak on the high pressure side of the regulator. CAUTION: Never use leak detecting fluids on any part of this system. Installing and Purging the Helium Purifier EZR21 1.
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Installation 9 Capillary Column Connection If the capillary column adapter is installed in the column inlet: 1. Make a mark on the column 11.4 cm from the end. COLUMN INLET CAPILLARY COLUMN ADAPTER (IZERA1.5) COLUMN FERRULE 11.4 cm/ NUT CAPILLARY COLUMN 2. Remove the knurled nut and plug from the capillary column adapter in the column inlet at the bottom of the detector. Slide the nut over the end of the column, followed by the appropriate column ferrule (FS.4 or FS.5, or ZF.5V for megabore). 3.
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Installation 10 3. Set aside the 1/8" wrench and completely remove the adapter from the column inlet. 4. Screw the packed column adapter into the column inlet by hand. Exercise caution, as the tip of the adapter is very fragile. Then tighten the adapter with a 1/4" wrench, using an additional wrench on the flats of the column inlet to support the detector. 5. Connect the 1/8" column to the packed column adapter with the EZRU21 reducing union supplied in the fittings kit.
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Installation 11 SWITCH MOUNTING NUT GREEN PIN 3 BLACK PIN 4 RED BLACK PIN 2 BLACK + RED PIN 1 BLACK - BLACK Figure 6: Pulser cable assembly Pulser Module Installation 1. Mount the pulser module in the pneumatics area of the GC, using existing slotted screw holes. (Figure 5) 2. Power to the pulser module is provided through cable assembly I-23628. Drill a 12.0 mm diameter hole in the front panel of the GC to mount the on/off switch. 3.
PAGE 14
Installation 12 Detector Electrical Connections CAUTION: Do not use a wrench to tighten the SMC connectors on the bias and electrometer cables. Connections should be finger tight only. 1. Referring to Figure 9 as necessary, connect the BIAS cable to the top electrode and the electrometer cable (ELECT) to the bottom electrode. 2. Connect the high-voltage cable from the detector to the pulse supply. 3. Connect the heater cable from the detector to the power board.
PAGE 15
Installation 13 Initial Power-Up 1. Set the discharge gas flow as specified in Figure 4 on page 7. CAUTION: Always make sure that discharge gas is flowing before powering up the detector. 2. Apply power to the helium purifier. 3. Turn on the pulser with the toggle switch. The discharge should start within five minutes. (Once a system has been up and running, the discharge will start within a few seconds.) In a clean system the discharge will have a peach/pink color.
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14 Mode Selection and Setup Helium Ionization Mode If the instructions of Step 1 at the top of page 9 were properly executed, the column should already be properly positioned. Since there may be some variation in the flow rate for the different types of capillary columns, the user may want to optimize the column position within this suggested range. DO NOT insert the column more than 11.6 cm.
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Mode Selection and Setup 15 Ar-PDPID Changing the discharge gas from helium to a mixture of 2% argon in helium changes the photon energy level from the 17 - 13.5 eV range to the 11.8 - 9.8 eV range. The argon emission consists of resonance radiation at 11.8 eV and 11.6 eV and the diatomic Ar2 emission in the range of 9.2 - 10.3 eV. Except for fixed gases and a few organic compounds like CH4 (IP = 12.5 eV), CH3CN (IP = 12.
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16 Warranty This Limited Warranty gives the Buyer specific legal rights, and a Buyer may also have other rights that vary from state to state. For a period of 365 calendar days from the date of shipment, Valco Instruments Company, Inc. (hereinafter Seller) warrants the goods to be free from defect in material and workmanship to the original purchaser.