GA 12.137/2.02 - 05/2002
Description
4
TSH 1
PI
29 bar
Ph
Pl
He
TSH 2
PSL
TSH 1
TSH 2
PI
PSL
He
Fig. 3 Flow chart for the COOLPAK compressor units
Figure 3 shows the flow diagram for a compressor unit.
The oil-lubricated, helium scroll compressor reduces the
volume of the helium gas, which becomes very hot in the
process. For this reason it is passed through a heli-
um/water counterflow heat exchanger located immedia-
tely downstream from the compressor; here the gas tem-
perature is lowered to about the temperature of the coo-
lant. A part of the oil fog swept out of the compressor
along with the helium is condensed to droplets here.
Downstream from the heat exchanger the helium is
passed through a two-stage oil separator. The conden-
sate from the oil separator is returned to the compressor
by means of capillary pipes.
The helium gas exiting the second oil separator will still
contain small quantities of oil vapor. To keep this oil from
entering the cold head and freezing there, an adsorber is
provided downstream from the oil separators. This ad-
sorber shall be replaced in accordance with the mainte-
nance schedule.
To cool the compressor, the oil is pumped through an
oil/water counterflow heat exchanger. Oil circulation is
maintained by the pressure difference between low and
high-pressure helium.
Safety equipment is installed in the compressor units;
details will be found in the table on the next page.
38
°
C Thermal switch
100
°
C Thermal switch
0 - 40 bar/0-600 psig/0 - 4 MPa
Pressure gauge
2.0 bar Pressure switch
Self-sealing
coupling
Helium recharging
Coolant
p
h
= High pressure
p
l
= Low pressure
