Record temperature (sensor
2) and vacuum values in the log (on the south side of the dome wall). Typical
values are 167.0K and 2-3x10-6 mB. Temperatures above 167.5K and pressure
values above 8x10-6 mbar should immediately be reported to ODT.
Remove cap from CCD dewar
(on the NE side).
Open LN2 tank valve for short
while so that only LN2 goes into the dewar.
Connect hose from liquid
nitrogen tank to the CCD dewar.
Open valve and start filling
the CCD dewar. Typical refill time is 10-15 min.
The LN2 tank pressure should be
0.4 mB, the refilling should not be done with high pressure in the tank.
On the other hand, if you suspect there is
not enough pressure in the liquid nitrogen tank or refill is taking too
long, you can open the valve (small handle) for 20-30 seconds. Do not forget
to close it.
Close valve when liquid
nitrogen starts over flowing from the CCD dewar.
Unplug hose from CCD dewar
and put the cap back on.
Finally, re-record the
temperature and vacuum values in the log.