Ulvac CRYOPUMP CRYO-U Series Instruction Manual page 21

filled 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. conducts the pressure proof test of the cylinder by
increasing the gas pressure to 1.5 times as high as the operating pressure.
It is strongly advised to handle corrosive substances with sufficient caution to the toxicity
and danger.
ULVAC CRYOGENICS INCORPORATED
3.
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