Ulvac CRYOPUMP CRYO-U Series Instruction Manual page 76

Maintenance
Cryopump
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 down the refrigerator unit. Charge helium gas to the refrigerator unit and
flexible hoses until the compressor gauge reading is the same as the static charge
pressure of the compressor unit (described on the front panel).
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
properly.
8-12
Compressor Unit
Power Cable
Cooling Water
Line
Flexible Hose
Coldhead Cable
ULVAC CRYOGENICS INCORPORATED
ＰＷＲ ＳＴＳ
１
ＲＤＹ ２
ＲＵＮ
３
ＣＨ１ ４
５
６
７
８
ＣＯＭ ＲＳＴ
Charging Adopter
Charging Hose
Ｖ２
ＳＵＰＰＬＹ
Charge Helium Gas
Ｖ１
ＲＥＴＵＲＮ
Release Helium Gas
Ｖ３
CAUTION
Regulator
Bottle Valve
High Pressure
Low Pressure
High Purity Helium Bottle