Ulvac CRYO-U Series, Instruction Manual, Page: 80 / 106

Maintenance
8-12
ULVAC CRYOGENICS INCORPORATED
Figure 8-5 Cryopump Decontamination Procedure (2)
h. Depressurize to 0.4MPaG by opening the valve (V1) during operating the refrigerator unit,
and then close the valve (V1).
i. While running the refrigerator, repeat the following operation 25 times surely slowly.
1) Charge helium gas until the pressure gauge shows 1.5MPaG by opening the valve
(V2) and close the valve (V2).
2) Depressurize to 0.4MPaG by opening the valve (V1) and close the valve (V1).
By taking the helium gas in and out 25 times, the purity of helium gas within the refrigerator
unit and the flexible hose should be increased.
９．
Shut off the refrigerator unit. Charge helium gas to the refrigerator unit and the flexible hose up
to the static charge pressure of the compressor unit.
１０．
Remove both SUPPLY and RETURN flexible hoses from the charging adopter.
１１．
Make sure that the flat rubber gasket of the self-sealing coupling is never disconnected nor
twisted. Then connect the flexible hoses to the compressor unit. (See Figure 8-6).
The pressure relief valve on the refrigerator may work if the charge inlet of SUPPLY
/RETURN at the compressor unit and SUPPLY /RETURN flexible hoses are connected
reversely, and this requires maintenance servicing. Make sure that they are connected
correctly.
CAUTION
High Purity Helium Bottle
Charging Adopter
Release Helium Gas
Charge Helium Gas
Charging Hose
Coldhead Cable
Flexible Hose
Line
Cooling Water
Cryopump
High Pressure
Low Pressure
Regulator
Bottle Valve
Compressor Unit
Power Cable
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1.
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2
2.
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3.
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D-P
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