89
Figure 38 is a plot of the purge pump-out schedule as a
function of saturated condenser temperature.
Figure 38. Purge pump-out schedule
Purge Service Log Reset
The purge service log reset is used to reset the Service Log
data in the Pump/Purge Report menu. This can be used to
track the pumpout time after the unit has been serviced.
Clearing the service log resets both the Service Log
Pumpout Time and the Service Log Time since Reset.
Purge Refrigerant
Suction Temperature
Terminate
Pumpout
Initiate
Pumpout
Compressor
On
Compressor off
Compressor
Off i
on
i
off
i
Saturated Condenser Temperature
i
Purge Setpoints
The set points used by the purge module are provided by
clear language display (CLD).
Purge Operating Mode
The purge-operating mode will indicate the desired mode
of operation. These operating modes will be Stop, On,
Service Pumpout. The default setpoint is on.
Maximum Pumpout Rate
The maximum pumpout rate is expressed in maximum
allowable minutes of pumpout per 24 hours. It will be
adjustable from 1 to 250 minutes. It is used to generate a
diagnostic when the actual 24-hour rate exceeds this value.
The default setpoint is 200 minutes.
Explanation:
Pumpout activity is indicative of the amount
of air leaking into the chiller refrigerant system. The
operator wants to know when the air leakage rate changes.
Through this set point, he can indicate the expected
leakage rate, and can set a criteria upon which to be
notified via a diagnostic should the rate be higher that
expected.
Inputs
Chiller Condenser Saturation Temperature (Liquid
Temperature)
The chiller condenser saturation temperature is provided
by the stepper module via the IPC.
Explanation: The chiller liquid temperature is used to
determine purge pumpout operation. The purge refrigerant
compressor suction temperature at which pumpout is
started and terminated is a function of chiller liquid
temperature.
Purge Refrigerant Compressor Suction Temperature
The purge refrigerant compressor suction temperature is
sensed via a thermistor device attached to the purge
refrigerant compressor suction line. The range will be -10 to
130°F.
Explanation:
The purge refrigerant compressor suction
temperature is used to initiate and terminate the pumpout
cycle.
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