The Pumproom

The He3 pumps: 8 roots blowers in series
Pumping speed at the intake: 13500m3/h
Operating pressure at the Still: 0.2 mbar at the lowest flow of 30 mmol/s and 1.2 mbar at 200 mmol/s
The pumping line to the cryostat: 20 m long, 320 mm in diameter.
Total pressure drop from the still to the intake of the roots pump: At a flow rate of 200 mmol/s the pressure drop is about 0.4 mbar across both the 320 mm line and the heat exchangers above the still.
Gas purification: To ensure trouble free operation, charcoal traps at room temperature and at 77 K are used to filter out impurities in the 3He return flow, in addition to the internal gas purification filters of the pumps.
The 4He evaporator pump: A Root's blower followed by a rotary pump
Pumping speed of the 4He pump: 2000 m3/h, maintaining the evaporator at 1.5 K. The cavity cooling line is connected directly to the rotary pump.
Amount of helium gas in the refrigerator (total amount of mixture): 8600 liters of NTP helium gas.
Amount of pure 3He: 1070 liters NTP.

3-APR-95