Varian 450-GC, User Manual

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Pulsed Pulsed Flame Flame Photometric Photometric Detector Detector (PFPD) (PFPD) - - Detectors Detectors
Varian, Varian, Inc. Inc. User User Manual Manual 450-GC 450-GC Page: Page: 363 363
Operation Operation
Adjusting the Gas Flow Rates Adjusting the Gas Flow Rates
The following procedure describe The following procedure describes the adjustment of the s the adjustment of the flow rates of the flow rates of the gases gases
to the PFPD. If to the PFPD. If you frequently adjust the column flow rate or you frequently adjust the column flow rate or change the carrier change the carrier
gas, you may want to gas, you may want to calibrate the air and hydrogen flow controllers. Once the calibrate the air and hydrogen flow controllers. Once the
flow controllers are calibrated, you can quickly select flow controllers are calibrated, you can quickly select new flow rates and use new flow rates and use
the optimization tables that are the optimization tables that are provided. provided.
If the PFPD If the PFPD Detector EFC option is installed on your 450-GC, detector gas Detector EFC option is installed on your 450-GC, detector gas
flows are flows are set by set by pressing pressing the the Detector ke Detector key, selecting y, selecting the PFPD the PFPD tab. tab.
The Split Valve The Split Valve adjustmen adjustment is t is described below. described below.
Split Valve Split Valve
A split valve is use A split valve is used to finely adju d to finely adjust the flow rate thro st the flow rate through the com ugh the combustor section bustor section
of the PFPD combustor. Follow these directions when adjusting this split valve: of the PFPD combustor. Follow these directions when adjusting this split valve:
1. 1. Disconnect Disconnect the ou the outlet line tlet line from the from the needle needle valve and valve and replace replace with a with a
flowmeter. flowmeter.
2. 2. With Air1 With Air1 and and Hydrogen turned on, Hydrogen turned on, close the close the needle valve needle valve by turning by turning the the
knob fully clockwise. The flowmeter should indicate a flow of knob fully clockwise. The flowmeter should indicate a flow of less than less than
1 mL/minute. If this is 1 mL/minute. If this is the case, disconnect the flowmeter and reattach the the case, disconnect the flowmeter and reattach the
outlet line. outlet line.
3. 3. If the flow If the flow from the n from the needle val eedle valve exceeds ve exceeds 1 mL/minu 1 mL/minute, remove te, remove the knob the knob by by
loosening the set screw. Rotate the valve stem loosening the set screw. Rotate the valve stem clockwise gently until the clockwise gently until the
flow from the outlet drops flow from the outlet drops below 1 mL/minute. Do not overtighten the valve below 1 mL/minute. Do not overtighten the valve
stem, as the needle valve does not need to stem, as the needle valve does not need to shut off completely to function shut off completely to function
properly and overtightening can damage the delicate needle in the valve. properly and overtightening can damage the delicate needle in the valve.
After making th After making the adjustmen e adjustment, reinstall the kno t, reinstall the knob on the va b on the valve stem and lve stem and
secure with the set screw. secure with the set screw.