Helium Circuit Decontamination - HELIX 8200 Operating And Service Instructions

8200 Compressor

Helium Circuit Decontamination

P/N 8040353
c. Connect the charge line to the helium pressure regulator.
d. Remove the flare cap of the gas charge fitting on the rear of
the compressor. Loosely connect the charge line to the
charge fitting.
e. Set the helium pressure regulator to 10 to 25 psig (70-125
kPa). Allow helium gas to flow through the charging line
and around the loosened flare fitting for 30 seconds to purge
the charging line of air. Then tighten the flare nut at the end
of the charge line.
(This procedure is required to ensure that both the regulator and the
charging line will be purged of air and that the air trapped in the regulator
will not diffuse back into the helium bottle. For best results, CTI suggests a
dedicated helium bottle, regulator, and line, which are never separated, for
adding helium.)
2. Set the helium pressure regulator to 300 psig (2070 kPa). Depend-
ing on the compressor operating state, add helium gas:
a. If the compressor is running (approximately 2 hours operat-
ing time) under normal operating conditions, slowly open
the helium charge valve on the rear of the compressor.
When the helium pressure gauge rises to 270 - 290 psig
(1860 - 2000 kPa) tightly close the charge valve.
b. If the compressor is not running, slowly open the helium
charge valve. When the helium pressure gauge rises to 245 -
255 psig (1688 - 1757 kPa), tightly close the charge valve.
Add helium gas slowly to prevent relief valve blow-off.
3. Ensure that the helium charge valve on the compressor is tightly
closed. Shut off the helium pressure regulator on the helium bottle
and remove the charging line from the male flare fitting. Shut off
the helium gas bottle valve. Reinstall the flare cap.
Refer to Section 4 - Maintenance of the appropriate On-Board Cryopump
Installation Operation, and Maintenance manual for information on helium
circuit decontamination.
CAUTION
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C TI CRYOGENICS
HELIX TECHNOLOGY CORPORATION
4-5