Recip compressor oil pressure too high ?

[kfjoe]

hi all,

I have a recip comp which seems to have a high oil pressure - 80 psi
this is above the range given in specifications , but what if any detrimental effect would this have ?

more importantly the compressor is losing oil and its not returning, even after a defrost , maybe it is being pumped out the compressot faster that it is returning?
I can actually see oil in the liquid line sight glass, its very white when running and at times i can actually see slugs of oil in there especially when not running.
all pressure and superheat etc seem fine and there seems to be a lot of oil in the system

any ideas please

any help would be appreciated Thanks

[RANGER1]

May be incorrect oil type ?
I do not think 80 psi will cause any damage in the short to mediem term.

[monkey spanners]

Are you running mineral oil in a system with HFC or HFC based drop ins?
This would account for the poor oil return and white liquid line sight glass.

Is this a new problem in an existing system?

[chemi-cool]

Oil pressure should be about 20 to 40 psi above suction pressure.

[Magoo]

What is the compressor, what are the operating conditions. More information required. System description.

[BESC5240]

Oil pressure should be about 20 to 40 psi above suction pressure.

Oil (pump) pressure should be related to cranckase pressure (and not suction pressure).

In several cases there is a difference between the suction and the crankcase pressure:

- in case of two stage compressor : the crankase pressure is the intermediate pressure

- could be something wrong in the (single stage) compressor : for exp. internal suction filter blocked : crankcase pressure is lower then suction pressure (mesured on the suction line).

- could be there is an internal bypass : cranckase pressure is higher then suction pressure; if you have several compressors on a rack and only measure common suction you will not notice this ...)

These are only a few cases ...

Conclusion : when measuring oil pressure, always measure crankcase pressure. ( AND NOT THE SUCTION PRESSURE : the suction pressure is misleading when it comes to interpreting the oil pump operation).

[kfjoe]

Thanks for the replies guys

The oil is POE and it is R404A gas
The oil pressure is 80psi above suction
It is a new problem in an existing system

I should also have mentioned it is part of a twin system (2 separate systems with interlaced evap) and the other compressor is fine, all pressures etc are almost identical to the other system, the other compressors oil pressure is 40psi

It is a Dx blast freezer with a twin system using bitzer recips