Compressor Lubrication System; Compressor Lubrication - Carlyle 06D Series Application Manual

2.0 Compressor Lubrication System

2.1 Compressor Lubrication

All refrigeration compressors must have adequate lubri-
cation to ensure trouble-free operation and a long life.
When starting up any new system, some oil will be lost to
coat the inside of the piping, some oil will be lodged in
low velocity areas of the system, and some will be kept
in circulation. This loss must be made up by adding oil
to the system after the initial start-up. Very low compres-
sor oil levels can cause complete loss of lubrication and
may result in an immediate compressor failure if not
protected against.
The loss of oil can also be caused by flooded starts or
refrigerant migrating into the oil during an off period
and pulling the oil out of its sump during the sudden
pressure drop of a start-up.
While it has always been apparent that very low oil levels
can cause compressor damage, it has also become
apparent that excessive oil charges can shorten the com-
pressor's life. Oil levels above the center of the 06E com-
pressor sightglass cause elevated crankcase and oil tem-
peratures, increased power consumption, and possible
valve plate gasket failures. This problem of excessive oil
charges has been mainly evident on 06E multiple com-
pressor applications and does not appear to have caused
any difficulties with the application of 06D compressors.
The oil level should be observed in the sightglass imme-
diately after the compressor shutdown, while it is still
warm. The level observed when the compressor is not
running for a long period may be a mixture of oil and
refrigerant which would not be a true indication of the
oil level when the compressor is running.
If the oil level in the sightglass of an 06E compressor is
less than one-eighth (1/8) up from the bottom of the
glass, this indicates a low oil level. If the oil level is up
more than one-half (1/2) from the bottom, this indicates
a high oil level. Therefore, the oil level should be 1/8 to
1/2 up the sightglass when the compressor is running
for 06E compressors.
Figures 6, 7, and 8 show different oil levels when a sin-
gle 06E compressor is running. The photos in each fig-
ure show the right and left sightglass of the same com-
pressor (only one sightglass is factory supplied). If the
level is not the same in each glass, consider the true oil
level to be the lower level. The difference in levels is due
to the rotation of the crankshaft. The crankshaft and
running gear are producing the windage required to
push the oil down on one side while raising it on the
other. Reversing the direction of rotation of the motor
will reverse this relationship.
Figure 6 – High Oil Level
The oil level in Figure 6 is at least 7/8 of a sightglass.
Note the high oil level in the left sightglass, and solid
foam in the right sightglass. Whenever the glass is filled
with foam, excessive oil is indicated and oil should be
removed.
Figure 7 – Better Running Oil Level
The oil level in Figure 7 is 3/8-1/2 of a sightglass. This is
an acceptable oil level on a single compressor system,
but does not always give a true indication of an excessive
oil charge on multiple compressor systems.
Figure 8 – Preferred Running Oil Level
The oil level in Figure 8 is 1/8-1/4 of a sightglass. The
sightglasses are showing a different level because of the
crankshaft rotation. Note the amount of clear glass above
the levels. These levels will ensure against the possibility
of excessive oil in the system.
15