Cryogen Liquid Level Monitors

LN2 Level Meter:

The liquid nitrogen level meter probe is a Magnex Scientific E5031. The probe is a continuous analog readout of the liquid nitrogen level. The active sensor area of the probe is approximately 1 meter. Read-out of the probe is done via a "hockey-puck" like attachment that screws into the top of the ~1m long probe rod. The probe is calibrated using a combination of a Zero offset adjustment on the hockey-puck and Gain adjustment on the back of the analog read-out. Typically the meter is calibrated using a known liquid level. The ammonia sample dewar is a good place to calibrate the liquid level if you think it is off. We usually only use the meter as a rough estimate of the liquid level so the calibration doesn't have to be super precise.

Description of images (starting top left and working clockwise):

1. Front of the Magnex Scientific LN2 Liquid Level and AMI Model 135 Liquid Helium Level Monitor. We currently do not use the Magnex E5011 Monitor. 2. Back of the Magnex Scientific LN2 Liquid Level and AMI Model 135 Liquid Helium Level Monitor. The gain for the LN2 monitor is adjusted using a small screw driver. The cable labeled LHe J1 for the AMI sensor originates in the 35 pin connector on top of the blue AMI magnet dewar. 3. The hockey puck attachment for the E5031 LN2 probe. The puck is attached to the probe rod in this picture. 4. The LN2 probe cable that attaches to the base of the hockey puck. 5. The LN2 probe cable that attaches to the back of the read-out electronics. 6. The zero offset adjustment on the hockey puck. This is changed with a small screw driver.