HELIX CTI-CRYOGENICS CRYO-TORR 100 Installation, Operation And Servicing Instructions page 32

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6.3 Assisted Regeneration
Regeneration incorporating the use of heated dry inert
purge gas (nitrogen/argon) is the preferred method of
regeneration and will overcome the unassisted
regeneration technical difficulties by:
1. Minimizing the required time to bring the condens-
ing and cryo-adsorbing arrays to room temperature.
2. Reducing the time required to rough the cryopump
because the dry inert purge gas will minimize the
amount of residual water vapor in the 15K array.
3. Diluting hazardous gases and ensuring their removal
from the cryopump housing.
REQIDRED ACCESSORIES FOR
ASSISTED REGENERATION
DESCRIPTION PART NUMBER
Purge gas heater 8080250K020
Purge gas solenoid valve 8080250K023
To accomplish assisted regeneration with heated dry
purge gas:
1. Close the
Hi-
Vac isolation valve.
2. Shut off the cryopump using the system power
ON/OFF switch on the controller or the compressor.
3. Immediately
introduce heated dry purge gas through
the vacuum vessel purge fitting at approximately
150"1< (66°C) and at a flow rate of 1-2 cfin. Allow
the purge gas to vent through the "poppet" relief
valve.
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eTl-CRYOGENICS
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4. Halt the gas purge when the condensing arrays
reach 80"1< (26°C) (300k).
5. When the condensing arrays reach ambient tem-
perature, rough the cryopump to an initial starting
pressure, usually between 50 and 100 microns.
After roughing, you can perform a simple check
{lYto ensure that your cryopump regeneration has
been thorough, and (2) that no air-to-vacuum leaks
arc present The check is called a "rate of rise"
(ROR).
Upon completion of your roughing cycle (to 50
or 100 microns), close the roughing valve and
observe the "rate of pressure rise" (ROR) over a five-
minute period. The ROR should be less than 10
microns/minute over a five-minute period (50-
microns total). If the ROR is greater than 50
microns, repurge the cryopump, check for evidence
of leaks, and repeat the roughing cycle and ROR.
6. Close the cryopump roughing valve and start
the cryopump.
7. The cryopump is ready for usc when the second-
stage array reaches a temperature of20K or lower.