Ulvac CRYO-U Series Instruction Manual page 21

UPS(Uninterruptible Power Supply system) installation
In case that the cryopump stops because of blackout etc, hydrogen explosion or
high-temperature combustion which must occur if high concentration of O
up in the pump with some source(s) of ignition such as O
UPS is necessary to prevent those hazards described in both cases of 1) and 2) above.
7. Rupture of refrigerator
cylinder by corrosion
The cylinder of refrigerator is mainly made of stainless steel and copper.
Special precautions must be taken when pumping corrosive gas which may be
produced by plasma reaction, sputtering, etc. in chamber, and corrodes cylinder
materials.
For maximizing performance of the refrigerator, the stainless steel cylinder thickness is
very thin. During normal operation, the pressure of helium gas in the refrigerator is
approximately 2 - 2.5 MPaG and if the corrosion develops, the cylinder may rupture at weak
portion.
☆ If the cryopump is used to pump corrosive gases, periodic pressure proof test is
recommended.
☆ ULVAC CRYOGENICS INC. executes the pressure proof test of the cylinder by increasing
the gas pressure to 1.5 times as high as the operating pressure.
Further, pay attention to the toxicity and danger sufficiently about handling the corrosive
substance.
8. Assembly and disassembly of refrigerator
The refrigerator contains high-pressure and high-pure helium gas. When disassembling
your refrigerator, please contact our Service Engineering Division or the nearest customer
support center for technical assistance.
If you will perform maintenance or disassembly of the refrigerator by yourself, take the
following special precautions for maintenance or disassembly of the refrigerator .
1. Exhaust the helium gas completely from self-sealing couplings on both helium return
and supply flexible hoses by using the charging adapter.
2. Make sure that the helium gas pressure has fallen on 0 MPaG and then loosen the
ULVAC CRYOGENICS INCORPORATED
or H
2
3.
is filled
2
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