11
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.
7. Open the cylinder valve to pressurize the regulator once again, then close
it and observe the high pressure gauge needle 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.
Installation
Installing and Purging a Purifier
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. Remove the cap from the inlet tube of the Valco helium purifier and insert
the tube fitting into the 1/16" reducer port. (Keep the outlet tube capped.)
Use a 1/4" wrench to turn the nut one-quarter turn past the point where the
ferrule first starts to grab the tubing. Do not remove the fitting. When
made up properly, it should be leak-tight.
3. Turn the output pressure regulating knob clockwise until the gauge
registers 345 KPA (50 psi).
4. Allow five minutes for equilibration, then turn the regulating knob all the
way counterclockwise.
5. Observe the needle of the output pressure gauge for 15 minutes. There
will be a slight initial drop, but if it doesn’t move after that, consider that
all the connections are tight.
6. If necessary, use an electronic leak detector to locate any leaks. If a
leak detector is not available, tighten all the fittings (including the output
pressure guage), and repressurize the system for another test.
7. Upcap the outlet tube of the purifier and purge the system for 15 to 30
minutes at 60 - 80 mL/min to eliminate air from the purifier getter material.
EZR21
