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During periods of low speed opera-
tion, the auxiliary oil pump may op-
erate continuously. With a variable
speed drive, the main oil pump will
not stop the auxiliary oil pump at low
speed. This is a normal condition.
3. Check that the oil pressure has increased and that
the auxiliary oil pump has stopped.
When starting a warm system with a
motor drive, the pre-rotation vanes
must only be opened partially to avoid
overloading the motor. On systems
equipped with automatic pre-rotation
vane control, the vane opening should
be limited automatically to prevent
motor overload.
Opening the pre-rotation vanes, as
soon as the compressor comes up to
speed, will reduce the tendency of the
oil to foam during starting and mini-
mize the opportunity to surge the com-
pressor.
4. Open the pre-rotation vanes as soon as the com-
pressor comes up to speed.
5. Be sure that oil foaming is visible only in the upper
region of the oil reservoir. The lower region should
show nearly clear oil.
6. If foaming becomes visible in the lower region and
adversely affects oil pressure, stop the compressor
immediately to prevent excessive foam from en-
tering the main oil pump suction at the jet nozzle.
During operation, foaming of the oil
at the jet nozzle/body is controlled by
cooling the oil.
YORK INTERNATIONAL
7. Opening the pre-rotation vanes and cooling of the
oil by the oil cooler will both reduce oil foaming and
oil pressure fluctuations.
8. Be sure the water valves to the oil cooler are wide
open and that the design flow of water is passing
through the cooler. It may be necessary to throttle
water to the coolers when the compressor is to op-
erate at reduced speeds, such as during turbine
warm-up.
During the "idle" period, with vari-
able speed drive, the main oil pump
will not produce sufficient pressure to
stop the auxiliary oil pump due to low
speed. This is a normal condition.
9. If, during a shutdown period, the reservoir heater
fails to function or if there is not sufficient time to
allow the heater to heat the oil, drain the oil from
the reservoir and replace with new oil of the proper
YORK designation before starting.
SUMMARIZED TYPICAL STARTING PROCEDURE
1. Be sure a full flow of water is flowing through the
oil cooler.
2. Move the auxiliary oil pump switch to AUTO-
MATIC and turn off the oil heaters, if manually
controlled. (Refer to the wiring diagram and the
application data sheet).
3. Start the compressor shortly after starting the aux-
iliary oil pump.
4. Stop the compressor if oil foaming is visible in
the lower sight region and adversely affects the
oil pressure. Do not wait for the oil failure switch
to function.
DAILY OPERATION
During operation, the following conditions should be
checked daily:
FORM 220.11-NM2 (602)
3
25
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