Exchange dewars

The Krios uses 25 to 30 liters of liquid nitrogen per day, the big tank is about 200 liters, we have two tanks just for the Krios.

With this level you want to replace it for the night:

kriosdewar_06.png


Everything is open:
kriosdewar_01.png


Close all valves and first disconnect the AutoLoader venting venting hose on the left, the white coupling:
kriosdewar_11.png


Disconnect the filling hose:
kriosdewar_10.png


Put a full tank in place.

Move the little hose piece to the new dewar:
kriosdewar_14.png


Open the venting valve, push the coupling a bit to flush it with nitrogen gas, otherwise we contaminate the autoloader when loading docking the next cassette:
kriosdewar_12.png


Connect everything else and open all valves:
kriosdewar_13.png


Fill empty dewar

Open the venting port a bit to release pressure, this will take some time:
kriosdewar_03.png


Once the pressure is zero, loosen the big coupling, use a wrench when it is stuck:
kriosdewar_04.png


Take off the pipe, clamp and O-ring:
kriosdewar_07.png


Bring the dewar down for re-filling like this:
kriosdewar_08.png


When the dewar is full again, close all valves, then remount the pipe and clamp, do not forget the O-ring! It should look like this: