OMM 1008-1
81
Then the system is once again evacuated to approximately 29 inches of mercury. This is repeated
three times. The first pulldown will remove about 90% of the noncondensables, the second about
90% of that remaining from the first pulldown and, after the third, only 1/10-1% noncondensables
will remain.
Charging the System
McQuay water chillers are leak tested at the factory and shipped with the correct charge of refrigerant
as indicated on the unit nameplate. In the event the refrigerant charge was lost due to shipping damage,
charge system as follows after first repairing the leaks and evacuating the system.
1.
Connect the refrigerant drum to the gauge port on the liquid line shutoff valve and purge the
charging line between the refrigerant cylinder and the valve. Then open the valve to the mid-
position.
2.
Turn on both the cooling tower water pump and chilled water pump and allow water to circulate
through the condenser and the chiller. (It may be necessary to manually close the condenser pump
starter.)
3.
If the system is under a vacuum, stand the refrigerant drum with the connection up, and open the
drum and break the vacuum with refrigerant gas to a saturated pressure above freezing.
4.
With a system gas pressure higher than the equivalent of a freezing temperature, invert the charging
cylinder and elevate the drum above the condenser. With the drum in this position, valves open,
water pumps operating, liquid refrigerant will flow into the condenser. Approximately 75% of the
total requirement estimated for the unit can be charged in this manner.
5.
After 75% of the required charge has entered the condenser, reconnect the refrigerant drum and
charging line to the service valve on the bottom of the evaporator. Again purge the connecting line,
stand the drum with the connection up, and place the service valve in the open position.
!
CAUTION
IMPORTANT: At this point, the charging procedure should be interrupted and prestart
checks made before attempting to complete refrigerant charge. The compressor must not
be started at this time.
(Preliminary check must first be completed.)
NOTE
: It is of utmost importance that all local, national, and international regulations concerning
the handling and emission of refrigerants are observed.
