Ulvac CRYO-U Series Instruction Manual page 79

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CRYO-U Cryopump Instruction Manual
a. Loosely connect the charging hose to the charge valve (V2) on the charging adapter.
b. Open the regulator until the outlet pressure reaches 0.1 to 0.2 MPaG. Allow helium gas to
flow out from the charging hose for about half a minute. Meanwhile, open the charge valve
(V2) slightly in order to drive out the air trapped in the charge valve.
c. Tighten the flair nut at the end of charging hose and close the valve (V2).
d. Start the roughing pump and open the valve (V3) slightly. Exhaust the helium gas in the
refrigerator unit while maintaining pressure below an allowable value of the roughing pump.
After the pressure reaches below the atmospheric pressure, the valve (V3) can be fully
opened. Therefore, monitor the pressure of the roughing pump head with an appropriate
pressure gauge. The maximum allowable pressure for ULVAC's small oil-sealed rotary
pump and drypump is 0.01MPaG.
Make sure to open the valve slowly when exhausting the gas beyond the atmospheric
pressure in order to maintain the pressure of the pump head below an allowable value.
If you open it quickly and widely, the roughing pump may break down.
e. After rough pumping for more than 30 minutes, close the valve (V3).
Shut off the roughing pump to bring it back to the atmospheric pressure.
f. Adjust the outlet pressure of the regulator at 1.8MPaG. Then open the valve (V2). Charge
helium gas until the pressure gauge on the charging adopter reaches 1.5MPaG and then
close the valve (V2).
g. Start the compressor unit to operate the refrigerator unit.
When operating the refrigerator unit, the helium gas is circulated through the refrigerator,
the flexible hoses, and the charging adopter. See Figure 8-5.
Do not operate the refrigerator unit when it is at a negative pressure. It may cause a
vacuum discharge in the motor of the refrigerator, and bring about a breakdown.
Helium gas charge has to be completed before starting the
ULVAC CRYOGENICS INCORPORATED
CAUTION
CAUTION
refrigerator.
8-11