Advertisement
To keep this gas concentration to a minimum during
shutdown, one or more thermostatically controlled oil
heaters are installed in the oil reservoir housing. These
heaters are factory set at 150°F. Some 26 inch com-
pressors are equipped with a 450 watt heater in the
seal trap which is not thermostatically controlled.
1. If the heaters are controlled by a manual switch:
A. Turn heaters on during shutdown.
The oil should be at the standby tem-
perature of 150°F before attempting
to start the compressor. Failure to do
so may result in oil pressure fluctua-
tions and oil failure switch initiated
safety shutdown.
B. Turn heaters off during operation.
2. If the heaters are automatically controlled check
that they are functioning properly. (Refer to the
wiring diagram and the application data sheet.)
CONTROLS
Each compressor should be equipped with the fol-
lowing controls:
Auxiliary Oil Pump Differential Control
Location
The auxiliary oil pump differential control switch is
mounted on the side of the compressor or in the Control
Center. Whenever this switch is mounted in the Control
Center, it is important that the correct size tubing be
used. (See SIZING THE OIL LINES FOR OIL PRES-
SURE SWITCHES).
Function
It automatically starts the auxiliary oil pump whenever
the main compressor oil pump does not maintain a nor-
mal operating pressure.
The auxiliary oil pump differential control switch is ac-
tuated by the pressure differential between the oil res-
ervoir and the main oil pump discharge, sensing the out-
put of the main oil pump only, independently of the aux-
iliary pump.
YORK INTERNATIONAL
Adjustments / Settings
This control should be adjusted, depending upon com-
pressor size as follows:
TABLE 5 – AOP DIFFERENTIAL SWITCH SETTINGS
COMPRESSOR
SIZES
26A 38A 55A
26B 38B 55B
ALL AFTER 1995
For compressors manufactured after 1995 the AOP
regulating valve should be adjusted to produce a 33 PSID
rise in oil pressure over sump pressure (at standby).
Low Differential Oil Pressure Control
Location
The low differential oil pressure control switch is
mounted on the compressor or in the Control Center.
(Tubing size may be a concern for protection monitored
in the Control Center.)
Function
It automatically opens the compressor driver control
circuit and stops the compressor if the oil pressure to
the compressor bearings falls below a safe operating
minimum. It is actuated by the pressure between the oil
reservoir and the filter outlet, sensing the combined out-
put of both the main and auxiliary oil pumps.
Adjustments / Settings
The low differential oil pressure control should be set
to stop the compressor if the differential pressure (be-
tween oil reservoir and oil filter outlet) falls to the dif-
ferentials listed below, unless indicated otherwise on
the lubrication oil diagram:
TABLE 6 – LOW OIL DIFFERENTIAL OIL
PRESSURE SWITCH SETTINGS
COMPRESSOR
SIZES
26A 38A 55A
26B 38B 55B
ALL AFTER 1995
FORM 220.11-NM2 (602)
OPEN
CLOSE
(PSID)
(PSID)
40
35
55
48
33
30
OPEN
CLOSE
(PSID)
(PSID)
27
30
40
43
23
20
29
3
Advertisement
