Operation; Rough Pumping; Pressure Buildup Test; Startup And Cooldown - Ulvac CRYOPUMP CRYO-U Series Instruction Manual

Operation

5.3

Pressure Buildup Test

１． When the pressure inside the cryopump reaches 40Pa, close the roughing valve
（RV1）and check the pressure buildup.
If the pressure buildup value stayed within 6.4Pa for five minutes, the roughing
process has been completed. If it increased 6.5Pa or more in five minutes, repeat the
rough pumping procedure described in Section 5.2.
２． After the test completed, rough pump the cryopump to 40Pa.Then close the roughing
valves (RV1) and turn off the roughing pump.
5.4

Startup and Cooldown

１． Start up the compressor unit.
When the cooling process reaches the stable state, the rubbed sound becomes small.
Oppositely, the inhalation sound and the exhalation sound of helium gas like choo-choo
become loud.
２． When the 15K cryopanel is cooled to 20K or less and the 80K shield is cooled to 130K
or less, the cryopump is ready to pump down. Refer to Table 1-1 for cooldown time of
the cryopump. If MBS-C CRYO-METER is attached on your cryopump, the
temperature of the 15K cryopanel is displayed as shown in Table 5-1. As MBS-C has
the function by which the thermocouple electromotive force is output directly, the
temperature of 80K shield can be measured with K thermocouple also. (Please refer
to MBS-C instruction manual for more details.) If Hydrogen Vapor Pressure Gauge
is mounted on 15K cryopanel and K thermocouple is mounted on 80K shield, refer to
Table 5-1 for their indications and outputs.
5-2
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ULVAC CRYOGENICS INCORPORATED