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Setup one of the liquefiers for Dewar Cooldown Production Mode:
1.) On automatic Incoming flow (FC501A/B) should be getting close to an average of around 50 slm. 60 slm is even better but generally, we want as much gas coming in and condense with the least amount of gas going out. This can be sporadic at times when things are stabilizing but when everything is working normally we should have a nice steady flow in of around 50 slm.
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The cold head temperatures should be averaging about 4-5K. If they are warmer it may be due to a flow dynamic of warm gas and there may be an adjustment of the NV501 needed. There may also need to be some balancing of flow performed by closing some of the helium gas delivery ball valves down. We have not yet needed to do this. The pressure on the dewar can be 6-7 psi and the flow in and out should generally be continuous. Some hiccups and periodic fluctuations are normal but long times with the inlet closed are not good. When everything is tuned right we should expect 4L/hour on each liquefier.
Vacuum pump out:
The vacuum of the dewars should in principle shouldn't need to be pumped out for a long time but we have already seen that Liq A performs better if it's pumped out at least every 2 months. When doing this make sure to pump down to at least low 10^{-3} torr and then close the turbo valve and check how fast it climbs (leak rate test). After all is well with the vacuum perform a pump and purge on the helium space of the dewar without going down much below atmosphere (can cause problems, or close all connections and remove stinger) and also perform the level pressure sensors cleaning procedure before starting the dewar cooldown.
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These regulators should not generally be changed. If they are bumped or accidentally changed follow this to reset them. Lower the dewar pressure at least 0.5 psi from the setpoint so that the inlet flow control is open all the way (easier in manual mode). It is usually useful to open the outgoing flow all the way too (60 in and 60 out) If the pressure jumps up when the flow controller opens then close the regulator down (turning to the left). If the flow is not able to reach the max (60 slm) that the flow control wants then gradually open the regulator (turn to the right) until the flow just nearly reaches 60 slm. In principle if one wants to operate the liquifiers at a higher or lower pressure you would need to reset these regulators so that at the new pressure they just barely open to 60 slm when the MFC is wide open. One may want to change the pressure to achieve optimal production rate or other possibilities. But once set for a particular pressure they should be good to go.