10 YORK INTERNATIONAL
abled at the instant of unit shutdown. This allows the
refrigerant pump to start at the beginning of the dilution
cycle without any delay.
PURGE
Since absorption chillers operate at pressures below
atmospheric, a purge system is required to remove sys-
tem impurities which degrade performance and cause
internal corrosion. The system employs a purge pump
motor and purge solenoid valve (wired in parallel), which
are manually controlled by the operator from the micro
panel keypad, and a manual purge valve (piped in se-
ries). On a typical system, a minimum of one purge cycle
is recommended each week. To initiate a purge cycle,
depress the PUMP STATUS key until PURGE PUMP
OFF is displayed; immediately, depress the HOLD key.
When the MANUAL PUMP key is depressed in LOCAL,
REMOTE, or SERVICE mode with the purge pump off,
the pump runs, the purge solenoid valve is energized
(opened), and the display indicates PURGE PUMP ON.
After the pump runs for about 20 minutes and the suc-
tion pressure as measured on a field-supplied manom-
eter falls to 1.6 mm of Hg absolute (0.03 PSIA), the op-
erator opens the manual purge valve while the pump
continues to run. AFTER about 30 minutes, the purge
cycle is complete and the manual purge valve is closed.
Although the purge cycle is complete, the pump and
solenoid valve are energized for an additional 30 min-
utes or until the suction pressure falls to 1.6 mm of Hg
(0.03 PSIA). The pump and solenoid valve are then de-
energized by depressing the MANUAL PUMP key a
second time, This allows the pump to clean its oil to ex-
tend pump life. After the purge pump runs for at least 10
minutes continuously, the 7 day and the unit lifetime purge
counters (displayed via the PURGE CYCLE COUNTER
key) increment by 1 count when the pump turns off.
The PURGE PUMP SERVICE INTERVAL key in the
Setpoints area of the keypad allows the operator to
select an appropriate interval for servicing the purge
pump. In PROGRAM mode, the key allows a cumulative
purge pump operating interval from 5 to 100 hours to be
entered. In addition, the display includes the number of
hours to be entered. In addition, the display includes the
number of hours that the pump has operated since the
last pump service. When the pump operating hours are
greater than or equal to the preset interval warning mes-
sage is displayed. After servicing the pump, pressing
the WARNING RESET key in SERVICE mode clears
the message and resets the counter. Moving the CLK
jumper from OFF to ON position also clears the counter.
The default value for the service interval is 10 hours.
To Next Page
Loading...
