VICI D-3-I-7890 - Manual (Page 15)

11
Installation
Gas Connections
Remember these three points discussed earlier: (1) all surfaces that contact
the gas stream must be glass 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. If your installation is different, you may need to modify
the instructions appropriately. A number of Valco fittings have been supplied
in the fittings kit to handle different situations. Since the distance from the
helium supply to the GC varies from installation to installation, we do not
supply tubing to go from that point to the GC.
Figure 6 illustrates gas connections for the PD-D3-I detector system. Since
the distance from the helium supply to the GC varies from installation to
installation, we do not supply tubing for that purpose.
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. Go
beyond finger-tight, but do not tighten the nut all the way – some leakage
is required for the purging operation.
2. Turn the output pressure regulating knob completely counterclockwise.
3. Open the cylinder on/off valve slightly and quickly close it again.
4. Adjust the tightness of the regulator connecting nut to allow a pressure
reduction of ~690 kPa/sec (100 psi/sec). With a new bottle, the gauge
should start out at about 14 MPa (2000 psi).
5. When the pressure drops into the 1.4 - 3.4 MPa (200 - 500 psi) range,
open the cylinder on/off valve slightly and quickly close it again.
6. Repeat Step 5 eight or ten times to be certain that all the air is purged.
On the final purge, tighten the regulator connecting nut very securely as
the pressure approaches the 2.1 - 3.4 MPa (300 - 500 psi) range.
GAS CHROMATOGRAPH
COLUMN INJECTOR
TEE
(ZT1)
HELIUM
PURIFIER
DISCHARGE GAS
(99.999% He)
TGA-R-30F60P
RESTRICTOR
(30 mL/min minimum)
COLUMN
INLET
DISCHARGE GAS
INLET
VENT
EPC
HPM
ELECTRONIC
PNEUMATIC
CONTROL
VICI
MINIATURE
HELIUM
PURIFER
Figure 6: Gas connections for a PD-D3-I system