Ulvac CRYOPUMP CRYO-U Series Instruction Manual page 20

regeneration.
(4) Be sure to use metallic pipes for the roughing system and exhaust lines in order to
prevent generation of static electricity. Ground the pipes with the grounding
resistance of 100 Ωor less.
(5) In case that the gas to be exhausted is hazardous and lighter than the dilution gas
(such as hydrogen gas), design and install the exhaust pipes so that its lighter gas
should not be accumulated in the pipes.
(6) Perform inert gas purge into the exhaust line in order to reduce the flammable gas
concentration below its combustion range before exhausting them away to
atmosphere.
(7) Perform inert gas purge as the regeneration starts.
(8) Assuming the pressure relief valve would work, connect the pressure relief valve to
the exhaust line in order to dilute the gases which might spout out from the valve.
(9) Be sure not to rough pump the cryopump without inspecting the state of the pump
just after power failure. As mentioned in the above ②, reduce the concentration of
hazardous gases in the pump and exhaust line by adding inert gas before rough
pumping. It helps to exhaust the vaporized gas safely out of the pump in case power
failure occurred.
(10) When adopting an oil-sealed rotary pump as a roughing pump, change lubricating
oils with Fomblin grease which is insensitive to oxygen. Instead, a drypump will be
fully recommended.
2. Safety measures in emergency
If troubles such as blackout, water outage, or pneumatic abeyance cause
suspension of a cryopump, take either among the following two actions.
1) When the cause of failure is eliminated before the temperature of the 2
reaches 20K, restart the cryopump.
2) When the temperature of the 2
the cause is eliminated. It is necessary to prepare some adequate devices to
introduce an inert gas automatically into both the cryopump and exhaust duct.
The devices include a thermometer, a valve for purge inert gas to the cryopump, a
valve for exhausting gases from the cryopump, an atmospheric pressure sensor
in the cryopump and a valve for introducing dilution gas into the exhaust line.
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
S-8
stage exceeds 20K, perform regeneration even if
nd
ULVAC CRYOGENICS INCORPORATED
nd stage
or H is
2 2