Support
will be low. The oil will be colder than usual, and therefore
thick. If oil is periodically disappearing from the crankcase
into the plant, then this situation requires investigation.
Refrigerant piping alterations could be required.
LEAKING UNLOADER MECHANISMS
In machines fitted with cylinder unloaders, a power element is
pressurised with oil from the force feed lubrication system in
order to cause a cylinder to load. This arrangement is repeated
for each of the unloading cylinder sets in the compressor. This
means involvement of an extensive oil system that could suffer
from an oil leak.
You will find that the first indication is a lubrication system that
works well when the compressor is unloaded, but which suffers
pressure loss when the machine begins to load.
Where three-way solenoid valves are used, these valves may be
accessible. If this is the case, you can power the solenoid valves, one
at a time. Each time a cylinder is loaded, a dip in oil pressure will be
observed while the power assembly is filling with oil. In the case of
a leak, the pressure dip will be sustained, identifying the issue and
corrective action can be taken.
Jackson, as you can see there are many reasons why you
may experience low oil pressures in your equipment, but
generally this is not a common problem. I have seen this a few
times. Blocked strainers and incorrect viscosity oils are what I
experienced. RACA
REFERENCE:
1. ACRA
Cylinder
unloading
Thank you for all your questions. Send your problems (and
sometimes your creative solutions) to [email protected] with
‘Solutions Page’ in the subject line. You may include pictures.
40
RACA Journal I October 2020
www.hvacronline.co.za