Valco Instruments Co. Inc. Pulsed Discharge Detector Models D-2 and D-2-I Instruction Manual Rev 2/14 North America, South America, and Australia/Oceania contact: Valco Instruments Co. Inc. 800 · 367· 8424 713 · 688· 9345 713 · 688· 8106 valco@vici.com sales tech fax Europe, Asia, and Africa contact:: VICI AG International Schenkon, Switzerland Int + 41 · 41 · 925· 6200 Int + 41 · 41 · 925· 6201 info@vici.
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Table of Contents Introduction Description and Operating Principles...............................................................1 Safety Notes and Information...........................................................................3 Symbols Installation Category Safety Maintenance Components of the Detector System...............................................................4 Description of Controls.....................................................................................
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1 Introduction NOTE: The contents of this manual apply to either the HID/ECD dual mode detection system (D-2) or the HID single mode detection system (D-2-I). In general, the manual describes the dual mode detector; information which applies specifically to the single mode detector is so indicated.
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.
Introduction 3 dynamic range whereas, in the D-2, a unique system of feedback to the bias electrode is employed. It operates by comparing the detector output current to a reference value and changing the bias voltage to maintain the detector current at the reference value. (E.g., in the presence of an electroncapturing compound, the bias voltage must be raised to maintain constant detector current.
Introduction 4 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.
Introduction 5 Description Quantity Product number Detector cell, PDHID/PDECD 1 PD-D2 Pulse supply module 1 PD-M2 1 I-23477 1 PD-C2 Cable, computer (unattenuated) output 1 I-23136 Cable, recorder (attenuated) output 1 I-23483 Instruction manual 1 MAN-PDD Fittings kit 1 PD-KIT-ECD 1/32" polyimide ferrule 5 ZF.5V 1/16" gold-plated ferrule 5 ZF1GP 0.25 - 0.44 mm polyimide column ferrule 5 FS.4 0.4 - 0.5 mm polyimide column ferrule 5 FS.
Introduction 6 MODE SWITCH 200 CURRENT SWITCH 16 32 64 128 256 4 512 1024 2 1 240 160 TEMPERATURE CONTROL RANGE SWITCH 8 280 120 PDECD 1X INCREASE 320 80 360 40 400 DETECTOR TEMP.
Introduction 7 TEMPERATURE control and indicator Sets the temperature (°C) of the detector heater block. The indicator is steadily on when maximum power is being applied to the heater, steadily off when no power is applied, and regularly blinking on/off when the set temperature has been established. Note that due to the fail-safe mechanism designed into the temperature controller, the heater will not operate if mains power is applied before the heater is connected or if the detector is too cold (< 0°C).
Introduction 8 Display Indicates standing current in the PDHID mode or bias voltage in the PDECD mode, auto-scaled to the most suitable range. In the un-zeroed PDHID mode, the display indicates the instantaneous signal current in nA. After zeroing, the display indicates the standing current by which the signal is offset. In the PDECD mode, the display indicates the controlling bias voltage unless the CURRENT switch or ZERO button is pressed, when it indicates the set current.
Introduction 9 Specifications Mains (line): 115/230 V~50/60 Hz, 175 VA Fuse: 2 A, time-delay, 5 x 20 mm Pressure: 6.9 kPa (1 psi) operating, 6.9 MPa (1000 psi) max. working Maximum temperature PD-D2-IS: 400°C PD-D2: 400°C Heater power: 60 W max., 48 V, PWM Sensitivity 10X range: 1X range: 1.0 V/nA 0.1 V/nA ± 1%* Range 10X: 10 nA full-scale 1X: 100 nA full-scale* Noise 1X: 20 fA/√Hz (referred to the input), 0.
10 System Requirements Components Not Included with the Detector System • Helium (99.999% purity) and other support gases • Ultra high purity grade gas pressure regulator with stainless steel diaphragm • Any special adapters required for connection to the gas regulator • Flow measuring device System Purity Discharge/Carrier Gas Considerations The performance of the detector is adversely affected by the presence of any impurities in the gas streams (carrier, discharge, or dopant).
System Requirements 11 Gas Specifications For Model D-2 Detector Mode PDECD PDHID Ar-PDPID Kr-PDPID Xe-PDPID Discharge gas Helium Helium 2% Ar in He Carrier gas Helium Helium * ** ** Dopant gas 3% Xe in He n/a n/a n/a n/a 1.5% Kr in He 0.
System Requirements 12 GC Column Selection To prevent detector contamination, we strongly recommend disconnecting the column from the detector during column bakeout procedures. PD-D2 The PD-D2 is optimized for packed columns with OD of 1/16" or less. Some of the stationary phases may not be compatible due to higher column bleed, manifesting in high detector background current.
13 Installation The detector is usually mounted on top of the GC column oven. The cabling as supplied requires the discharge module to be located within 0.6 m (2') of the detector and the controller to be within 1 m (3.5') of the detector and discharge module. The power cord for the controller is 1.8 m (6') long, and the signal output cables (attenuated and unattenuated) are 1.2 m (4') long. General Precautions • Do not use plastic/polymer or copper tubes for gas handling and interconnectons.
Installation 14 Horizontal Mounting Some older GCs have access to the column oven through the side of the GC. This does not present a problem as far as operation of the PDD is concerned. Drill a hole at the appropriate location, orient the detector for convenient connection, and mark the position of the mounting holes. Drill the mounting holes and secure the detector to the side of the GC with four sheet metal screws (not supplied).
Installation 15 DISCHARGE GAS INLET TGA-R-50F50P RESTRICTOR (50 mL/min minimum) TEE (ZT1) HELIUM PURIFIER DISCHARGE GAS (99.999% He) COLUMN INLET COLUMN INJECTOR GAS CHROMATOGRAPH VENT Figure 4: Gas connections for a PD-D2-IS system Installing and Purging the Gas Regulator 1. Make sure the on/off valve on the helium cylinder is completely closed. Screw the CGA fitting nut of the regulator into the helium cylinder.
Installation 16 Installing and Purging the Helium Purifier EZR21 1. If the pressure regulator has a 1/8" male cone-type outlet port, install the Valco 1/8" external to 1/16" internal reducer (EZR21); if it has a 1/4" male cone-type outlet port, install the Valco 1/4" external to 1/16" internal reducer (EZR41). For other regulator outlet fittings, a wide variety of Valco adapters are available. 2.
Installation 17 Column Connection The following applies only to systems with the PD-D2 detector. On the PD-D2-IS detector, the column is connected to the column inlet tube with a 1/16" union, and does not extend into the detector. 1. Make a mark on the column at the length indicated below for PDHID or PDECD operation, as appropriate for your application. If a ruler is not handy, place the end of the column over the figure below to determine how far into the detector body the column must be inserted.
Installation 18 4.0 3.5 ECD Mode Detector temperature: 50 C Working current: 15 nA Sample: 50 ppb freon-11 2 l loop 3.0 Peak height (nA) 2.5 2.0 1.5 1.0 0.5 0.0 9.2 3.5 3.0 9.4 9.6 9.8 10.0 10.2 10.4 Length of column in detector (cm) 10.8 10.6 HID Mode Detector temperature: 50 C Sample: 100 ppm n-C5 2 l loop Peak height (nA) 2.5 2.0 1.5 1.0 0.5 0.0 10.6 10.8 11.0 11.2 11.4 Length of column in detector (cm) 11.6 11.
Installation 19 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 6 as necessary, connect the bias and electrometer cables as follows: the BIAS-B cable to the top electrode (closest to the discharge electrodes), the electrometer cable (ELECT) to the middle, and the BIAS-A cable to the bottom electrode. This setup is the same for both detector models. 2.
Installation 20 Initial Power-Up NOTE: This section refers to the D-2 operating in the HID mode and to the D-2-I. For instructions on using the D-2 in the ECD mode, see page 25. However, we recommend that D-2 users test system integrity by proceeding with the instructions below before switching to the ECD mode. 1. Set the MODE switch on the front of the controller to PDHID. 2. Set the discharge gas flow as specified in on page 16 in the section entitled “Connecting the Discharge Gas to the Detector”.
Installation 21 NOTE: Some stationary phases will have a higher bleed than others, but are still suitable for this detector. However, the lower the bleed, the lower the chances of contaminating the detector cell. From this point, the standing current should be observed and logged after any system change. In addition, logging the standing current (with and without the column) on a regular basis is an effective monitor of system integrity (leak-tightness and cleanliness).
Installation 22 Column Bakeout Precautions To prevent detector contamination, we strongly recommend disconnecting the column from the detector during column bakeout procedures. When the column in reinstalled after bakeout (refer to page 17 if necessary), the standing current should be at an acceptable level. If you have exhausted these troubleshooting methods and the standing current is still high, consult the factory.
23 Mode Selection and Setup Helium Ionization Mode Since the PDHID mode provides a better indication of the cleanliness and the integrity (leak tightness) of the system, that mode is utilized for initial testing and startup. If the system is operating according to the parameters described thus far, it is ready for operation in the PDHID mode. In the PD-D2-IS, the column connects directly to the inlet, and cannot be adjusted. However, the PD-D2 may require some additional work on the column positioning.
Mode Selection and Setup 24 amounts of pure helium and pure dopant through a tee. Since all gas streams must pass through a Valco purifier, the second option requires an additional purifier for each dopant. This may still be more cost effective than requesting a custom blend of the more expensive Kr or Xe; since the typical flow rate required for the pure dopant rare gas is about 0.3 - 1 mL/min, a small lecture bottle can last for a long time.
Mode Selection and Setup 25 Electron Capture Mode (PD-D2 only) Since the PDHID mode provides a better indication of the cleanliness and the integrity (leak-tightness) of the system, we utilize that mode for initial testing. If the system is operating according to the parameters described thus far, it is ready for operation in the PDHID mode. To configure the PD-D2 to operate in the PDECD mode: 1. If the discharge is not already established, turn on the MAINS switch and the DISCHARGE switch.
Mode Selection and Setup 26 10. If the bias voltage is not 1 V or less with a set current of 10 nA, the dopant flow rate may need to be adjusted. The optimum flow rate is determined by varying the rate until the indicated bias voltage is minimized, and then increasing the rate very slightly. Figure 7 illustrates the effect on background bias voltage and detector sensitivity with varying dopant flow rates.
Mode Selection and Setup 27 10 ECD Mode Background bias voltage V0 (V) Detector temperature: 50 C Discharge gas flow-rate: 32 mL/min Iw = 20 nA Iw = 10 nA 1 0.1 0.0 100 10 1.0 2.0 3.0 4.0 5.0 Dopant Flow-rate (3% Xe, mL/min) 6.0 7.0 ECD Mode Detector temperature: 50 C Discharge gas flow-rate: 32 mL/min Sample: 50 ppb freon-11 2 l loop Iw = 20 nA Peak Height (V) Iw = 10 nA 1 0.1 0.01 0.001 0.0 1.0 2.0 3.0 4.0 5.0 Dopant Flow-rate (3% Xe, mL/min) 6.0 7.
Mode Selection and Setup 28 1.8 1.6 Bias voltage V0 (V) 1.4 1.2 1.0 0.8 0.6 0.4 0.
29 Appendix: PD-C2 Controller (shipping February 2014) If you have been directed to this part of the manual, you are probably replacing an older PD-C2 controller or have received a new Pulsed Discharge Detector with the latest design. If that is the case, congratulations. You have the latest and greatest controller as a component of a truly remarkable detector system.
Appendix 30 UNATTENUATED OUTPUTS Normally connected to a data acquisition system or other recording means. The two unattenuated outputs are 0 - 10V full scale and 0 - 1V full scale. Output are provided, with an internal signal reference (-) at zero volts. For best noise performance, the shield (earth) and signal reference (-) should not be connected together. The internal impedance of these outputs is 1000 ohms.
Appendix 31 Figure 10: Electrical connections Note About Compatibility Obsolescence planning is a significant portion of manufacturing control, as the speed at which electronic components come to market and reach end
32 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.
33 Detector Performance Log In addition to the occasions indicated in the Comments area of the table below, (see Initial PowerUp, page 20), the standing current should be observed and logged after any system change. Logging the standing current (with and without the column) on a regular basis is also an effective monitor of system integrity (leaktightness and cleanliness). To check sensitivity continuity, we recommend tracking the internal standard (quantity on column/area count).
