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ULVAC CRYOGENICS INCORPORATED
8.2.2 Start-up
(1) Press the RUN/STOP button on the operation panel to turn ON (lights green).
UW701N starts up and LN
2
production starts.
(2) Since inside of liquid nitrogen dewar is at room temperature at initial start-up, it is
necessary to take the time to cool inside of the dewar. (It normally requires about
half a day.) When the dewar is sufficiently cooled, production of liquid nitrogen
starts. The production continues until liquid nitrogen in the dewar reaches 100
litters (100%). After that, production starts when the amount of remaining liquid
nitrogen is below 75L (75%), and stops at 100L (100%). This cycle goes on
repeatedly.
8.3 Shutdown
When the RUN/STOP button is turned OFF (lights off), all the operation of MP-300K
including LN
2
production or supply stops. Caution is advised for items as follows.
(1) Do not attempt to interrupt the nitrogen gas supply.
When nitrogen-gas supply stops, LN
2
production also stops. The cold
head right after stopping the operation is at extremely low temperature and
likely to cause water condensation or freezing. Therefore, when moisture
in the atmosphere enters, ice or frost might be generated. Do not stop
nitrogen gas supply for ten minutes after the system is shutdown.
*
Note that allowing ice or frost may bring about the drawbacks shown below.
Decrease of liquefied nitrogen production
Liquefied nitrogen supply failure
Level sensor failure
(2) Shutdown procedure
Follow the steps below when shutting down MP-300K for reasons such as
utility stop.
1. Turn OFF RUN/STOP switch of MP-300K. After the LN
2
production
(UW701N) stops, turn OFF the breaker.
↓
Wait for 10 minutes or more.
2. Turn OFF the GN-20i POWER to shutdown, and turn OFF the GN-20i
breaker. Or, close the nitrogen-gas source valve to stop supply. Or,
stop cooling-water supply.
NOTE:
By waiting for longer than 10 minutes after shutting down LN
2
production, the edge of the coldhead is warmed up, reducing the air intake.
When stopping cooling-water supply, turn OFF the MP-300K RUN/STOP
