RWB II ROTARY SCREW COMPRESSOR UNITS
OPERATION
S70-200 IOM
Page 22
SUCTION CHECK VALVE
Low temperature booster compressor operations require
a more pos i tive suction check valve closure. This is ac-
com plished by al low ing the high stage discharge pres sure
gas to assist the spring tension and intermediate pres sure
clos ing force.
Frick provides a power assist kit consisting of a mounted
and wired so le noid valve and tim er on all RWB II booster
compressors. High stage compressors are supplied with
a power assist kit when the de sign suc tion tem per a ture is
less than or equal to 0°F. The wiring di a gram in S90-010 M
(Quan tum) or S70-200 OM (Plus) shows the wiring in clud ed
when re quired. In tro duc tion of high dis charge pres sure gas
is made to the check valve. A timer limits the high pressure
gas to only thirty sec onds du ra tion since in ter me di ate gas
Figure 23
Figure 22
Use the [Control], [Action] and [Off Value] keys to set the
following:
• Set
the
Control for: When Running
• Set
the
Action for: Forward
• Set
the
Off Value for: 0%
• The
ACTUAL value should be reading the current dis-
charge temperature.
• The
Output should be reading 0% with the machine
off line.
• Regarding the adjustment of the Proportional Gain
setpoint, the goal is to increase or decrease the Pro-
portional Gain setpoint, until the discharge temperature
holds within or close to the Dead Band with minimal
fl uctuation of the output signal.
