HELIX CTI-CRYOGENICS CRYO-TORR 100 Installation, Operation And Servicing Instructions page 4

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CRYOPUMP OXYGEN PROCEDURES
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AWARNING
COMBUSTION SUPPORTED BY OXYGEN IN THE PUMP COULO CAUSE
SEVERE INJURY. WHEN OXYGEN IS USED AS A PROCESS GAS, SPECIAL
PRECAUTIONS DESCRIBED IN THE TEXT BELOW SHOULD BE TAKEN.
When oxygen is used as a process gas, the following precautions should be taken.
1. Follow all cryopump operaling instructions including:
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• Insure that there are no sources of ignition (e.g., hot filament vacuum gauges) on the cryopump side of the high vac valve
operating during the warming or venling of the pump.
• Perform inert gas purge regenerations at flow rates recommended for cryopumps.
2. Regenerate as frequently as praclical to minimize the amount of oxidizer present in the cryopump.
3. It is standard practice in the vacuum industry that any system exposed to richer·than·air oxygen levels should be prepared for
oxygen servICe per the manufacturer's recommendations, including use of oxygen service lubricating oils in roughing pumps.
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AWARNING
EXPLOSION OCCURING FROM OZONE IN THE PUMP COULD CAUSE
SEVERE INJURY. OZONE CAN BE PRESENT AS A BY·PRODUCT OF
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OXYGEN PROCESSES. IF OZONE IS PRESENT, SPECIAL PRECAUTIONS
DESCRIBED IN THE TEXT BELOW MUST BE TAKEN.
Ozone may be unknowingly produced in an ionizing process (e.g., sputtering, etching, glow discharge). Explosive conditions may
exist if ozone is present, especially during warming of the cryopump. Signs of ozone's presence are:
1.
Crackling/popping sounds (as in electrical arcing) occurring within the first few minutes of regeneration,
2. Gas venting from the cryopump during regeneration may have a pungent smell, similar to that present in an arc welding opera·
tion or after an electrical storm.
NOTE: A change in process may increase the amount of ozone present.
If ozone is present, the following precautions must be taken.
1.
All of the above oxygen precautions must be followed. The required regeneration frequency is dependent upon flow
and process conditions. Daily regeneration may be required. Call CTf.CRYOGENICS for assistance.
2. Reduce the oxygen mixture to the lowest level the process will allow.
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