Oil Pumps; Oil Pressure; Oil Circulation; Oil Level - Emerson Copeland Stream 4MF-13X Application Manuallines

2.6.6 Oil pumps

The oil pumps used for Stream compressors are independent of their rotating direction.
On compressors delivered with CoreSense™ Diagnostics (-D), the oil pump integrates the
electronic switch for integrating oil pressure safety functionality.
Compressors with CoreSense™ Protection (-P) are designed to accommodate fittings for an
OPS2, FD-113ZU, or Sentronic oil safety system or a standard oil pressure switch (OPS2 oil
sensor included in the oil pump).

2.6.7 Oil pressure

Normal oil pressure is between 1.05 and 4.2 bar higher than crankcase pressure. Net oil
pressure can be read by connecting two pressure gauges to the compressor and comparing the
readings. One gauge should be connected to the oil pump. The second gauge should be
connected to the crankcase (T-fitting instead of plug on the compressor crankcase) or the
suction service valve.
During irregular operating conditions, eg, a blockage of the suction filter, the pressure measured
at the suction shut-off valve of the compressor may differ widely from that measured at the
crankcase. Therefore pressure drops have to be avoided.

2.6.8 Oil circulation

Oil returns with the suction gases through a suction strainer and separates in the motor chamber
reaching the crankcase by way of oil return relief valve in the partition between motor housing
and crankcase. This relief valve closes on compressor start-up due to the pressure difference
arising between motor side and crankcase, thus slowing down pressure decrease in the
crankcase over a certain period of time. It reduces the foaming of the oil/refrigerant mixture that
would occur if the pressure decreased rapidly. The valve does not reopen until the pressure has
been equalized by means of a crankcase ventilating valve. This second valve connects the
crankcase and suction side cylinder head. It reduces the pressure difference by means of a very
small bore in the plate of the valve so slowly that oil foams less and only limited oil/refrigerant
foam is transferred to the oil pump.
Four-cylinder compressors have one crankcase ventilating valve on the left cylinder bank
whereas six-cylinder compressors have two ventilating valves on the left and right cylinder
banks.

2.6.9 Oil level

All compressors are delivered with sufficient oil for normal operation (see Table 2). The optimum
oil level should be checked by operating the compressor until the system is stable and then
comparing the sight glass reading with the appropriate diagram below. The oil level should be
min ¼ and max ¾ of the sight glass.
For service compressors when an oil regulator is used the oil level should be min ¼ and max ¾
of the sight glass. The level can also be checked within 10 seconds of compressor shutdown.
For 4M* and 6M* compressors a higher oil level may be accepted when an oil regulator is in use
because the oil separator will reduce excessive oil circulation.
Figure 3: Sight glass reading on 4M* and 6M* compressors
6 C6.3.1/0116-0716/E