rack oil press faillure

[jrrefrig]

have a rack , roof top location. this 4 compressor lo temp rack has locked out twice on oil fail (all compressors).any input on where the oil is hanging up to cause all units to have to be reset.

[Mark]

There are many things which could cause this..

Post more details on the set up i.e oil separator type,refrigerant ,oil type,operating pressures / temperatures,oil managment,etc.

It could be anything from oil seperation to flooded starts

[chillin out]

Clean the oil seporator and any oil filters in between.

Make sure oil in sep is at a higher pressure than the compressor bodies.

When you return to site after they have tripped, is there oil in the compressors? How much?

Is there oil in the sep? How much?

Have you gone to site to check the oil levels before they get a chance to trip? What are the levels like?

As Mark says, there is many many things that can cause oil shortage.

Chillin

[monkey spanners]

I,ve seen a tap in the oil return line on a pack with no hole machined in it when it was made. Took some finding.

Cheers Jon

[Peter_1]

Is this a pack already long running? (important!!)
Height difference?
Does the pack run longer times on partial load?
VFD controlled?
Lack of gass and more in general lack of gass speed is often the cause for improper oil return to the pack.
Multiple risers?

[mr cool]

are you getting liquid flood back on your pack? what type of oil switces, are they bellows type or "magic" eye type? and are they isolated when comps are not running, have known them to still be fed when comp stops and then time out. also are the overloads auto reset? that would do it too.