Carrier 19XL Oil Reclaim System

journalbearings within the bearing housing. The oil then drains

into the oil reservoir at the base of the compressor.The PIC

(ProductIntegrated Control) measures the temperature of the

oil in the sump and maintains the temperature during shut-

down(see Oil Sump Temperature Control section, page 32).

This temperature is read on the LID default screen.

During the chiller start-up, the PIC will energize the oil

pump and provide 15 seconds of prelubrication to the bear-

ingsafter pressure is veriﬁed before starting the compressor.

During shutdown, the oil pump will run for 60 seconds to

post-lubricateafter the compressor shuts down. The oil pump

canalso be energized for testing purposes in the Control Test.

Ramp loading can slow the rate of guide vane opening

to minimize oil foaming at start-up. If the guide vanes

open quickly,the sudden drop in suction pressure can cause

any refrigerant in the oil to ﬂash. The resulting oil foam

cannot be pumped efficiently; therefore, oil pressure falls

off and lubrication is poor. If oil pressure falls below

15 psid (103 kPad) differential,the PIC will shut down the

compressor.

Oil Reclaim System — The oil reclaim system oper-

ates to return oil back to the oil reservoir by recovering it

from 2 areas on the chiller.The primary area of recovery is

from the guide vane housing. Oil also is recovered, along

with refrigerant, from the cooler.

Any refrigerant that enters the oil reservoir/transmission

area is ﬂashed into gas. The demister line at the top of the

casing will vent this refrigerant into the suction of the com-

pressor.Oil entrained in the refrigerant is eliminated by the

demister ﬁlter.

DURING NORMAL CHILLER OPERATION, oil is

entrained with the refrigerant. As the compressor pulls

the refrigerant into the guide vane housing to be com-

pressed, the oil will normally drop out at this point and

fall to the bottom of the housing where it accumulates. Us-

ing discharge gas pressure to power an eductor, the oil is

vacuumed from the housing by the eductor and is dis-

charged into the oil reservoir. Oil and refrigerant are also

recoveredfrom the top of the cooler refrigerant level and are

dischargedinto the guide vane housing. The oil will drop to

the bottom of the guide vane housing and be recovered by

the eductor system.

DURINGLIGHT LOAD CONDITIONS, the suction gas into

the compressor does not have enough velocity to return oil,

which is ﬂoating in the cooler back to the compressor. In

addition,the eductor may not have enough power to pull the

oil from the guide vane housing back into the oil reservoir

due to extremely low pressure at the guide vanes. Twoso-

lenoids, located on the oil reclaim piping, are operated so

thatthe eductor can pull oil and refrigerant directly from the

cooler and discharge the mixture into the oil reservoir.The

oil reclaim solenoids are operated by an auxiliary contact

integral to the guide vane actuator. This switchover of the

solenoids occurs when the guide vanes are opened beyond

30 degrees from the closed position.

Fig. 4 — Lubrication System