HELIX CTI-CRYOGENICS On-Board FastRegen Programming And Operation Instructions page 42

Programming and Operation
From page 3-27
ROUGH 125 µ /50 µ
REPURGE #1 2M
ROR 3 124 µ /10 µ
Continued on page 3-29
Figure 3-25: On-Board Cryopump Full Regeneration Cycle Example (continued)
3-28
Displays the current pressure (125 µ) and the base pressure to be
achieved (50 µ). The cryopump is roughed out until the base
pressure is reached.
If the pressure does not reduce at a reasonable rate during the rough
out phase, the On-Board FastRegen Control Module will automatically
repurge the cryopump for the programmed REPURGE time. The dis-
play indicates that this is the first purge cycle (#1) and that there are
two minutes (2M) remaining in this cycle.
The cryopump is roughed out again until the base pressure is reached.
The following events occur:
- Cryopump TC reaches programmed base pressure of 50 µ
- Rough valve closes and the On-Board FastRegen Control Module
waits 15 seconds to stabilize
- On-Board FastRegen Control Module measures TC pressure and
takes second reading in 30 seconds
- On-Board FastRegen Control Module calculates ROR pressure
increase in µ/minute
- If ROR is less than programmed value, the ROR test passes
- If ROR is more than programmed value, the ROR test is repeated
The display indicates the number of ROR test cycles (3), current ROR
value (124 µ/ µ), and the programmed ROR value (10 µ/ µ).
If ROR test is repeated:
- Rough valve opens
- Cryopump is roughed out again to base pressure
- ROR test is repeated
-
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