4He Reservoir Maintenance Items
Using the Electronic Helium Level Monitor
- Make sure the controller is connected to an ac outlet.
- Connect the sensor to the teflon cable.
- Disconnect the red rubber flowmeter hose from the fill tube on SPARO.
- Insert the level sensor into the fill tube carefully until the end reaches
the bottom of SPARO's reservoir.
- Turn on the controller and push "continuous read". After a few moments,
the LED readout should display the level of helium in the reservoir. Note
that this level should be about 1/2 inch less than that obtained with a thumper,
as the sensor stick has 1/2 inch of dead length at the end.
- Remove the sensor from SPARO and Replace the red rubber flow meter hose onto the fill tube.
Filling SPARO's 4He Reservoir
See photos of this process
- Using one of SPARO's two Helium transfer tubes, Insert the large end into
the 100L Helium dewar.
- Push the tube into the dewar and wait until liquid begins to shoot out
the other end. This is evident by a small but violent plume.
Note: It is not a good idea to have the transfer tube touching the bottom
of the 100 L dewar as it could suck up a lot of ice and sludge and cause an
eventual capillar plug in SPARO.
- When the plume is evident, remove the red rubber flowmeter tube from
SPARO's fill tube and insert "stinger" end of transfer tube into SPARO. Allow
the end of the stinger to rest about 1 inch from the bottom of the SPARO reservoir.
- At this point, allow SPARO to fill. A fill is complete when a change in
the plume is noticed. Also, it is possible to stop the transfer at any point
in order to measure the level either with the electronic level sensor or the
"thumper". Note also that it has been possible in the past to fill with the
electronic level sensor in the fill tube along with the stinger, although
this technique has shown some unreliability when SPARO is mounted on Viper.
- When the reservoir is judged to be full, remove the stinger from the
fill tube and then remove the transfer tube from the transfer dewar.
- Replace the red rubber hose on the fill tube.
- NOTE: Make sure that the low pressure relief valve on the 100 L
transfer dewar is closed when doing transfers, but open otherwise. This
prevents large pressures from building up in the dewar which can be dangerous.