Camera Filler and Dispenser Tubes

The LN2 cans of our 2.5l cryostats have internal dimensions of 123.5mm diameter x 209.5mm height. There are two lengths of filler tube, Long/Full length for inverted operation and Short/Half for optimisation of fill time if the attitude of the camera is completely random (as for example at CASS on both INT and WHT). The optimum lengths are given below, measured from the inner end of the threaded section of the fill tube to the end that is inside the can.

 Short/Half : 125mm

Long/Full length : 210mm

The Dispenser tubes (temporarily inserted during cryostat filling) should be long enough so that they penetrate the full length of the Filler tube and protrude a few mm's on the inner end. The length of a dispenser, as measured from the shoulder section to the end at which the LN2 exits should be > 350mm

 For INGRID, the distance to the base of the LN2 can to the top of the filler port is 315mm. When used in inverted operation, the gap between the filler tube and the base of the can is 25mm. The CCD dispenser tubes are thus suitable for INGRID also.