super market refrigeration pack low on oil

[ben7777]

can i ask please , i have a pack low on oil . iam new to supermarkets , its a space pack , with a discharge seperator / oil reservoir,, is it best to turn the pack off , then blow of whats in the sep, in order to put oil init , didnt fancy doing that due to the number of cases on the pack , any ideas please, did end up topping up each comp , but took for ever , and still had no level in sep,

[Glenn Moore]

Ben have you checked that the oil control system is working correctly. Where has the oil gone? . Is it logging in the cases. Who's oil control system is fitted , what refrigerant is in the system ?.

[ben7777]

yes , they seem ok emerson , just seems low on oil pack , i do know there has been leaks on this unit over the years , must admit i did switch it off for ten minutes just to see if i can rise back pressure, see if that brings back a bit of oil , but no joy, its on 404 a , low temperature pack , thanks for reply, but i do feel its just low on oil , wondered , how other engineers got oil in the pack , i know how to do it with a shut down , just wanted a quicker way if anybody knows thanks

[Grizzly]

Hi Ben
Welcome to the forum!
I don't deal with the type of pack you are talking about.
But the basics of any system are oil added should as near as is possible add up to the amount of oil drained.
It is a very common issue where systems don't run at high loads for long,but run part loaded most of the time.
The resultant low gas volume through a system will allow oil to be carried to the lowest pressure part of the system.
Namely the evap, plate pack . cabinet or whatever!

The trick is to individually run up comps to full load (Manually if necessary?)
To get sufficient gas Flow / Volumes to start returning oil back.
You will need to run the plant for 15 to 30 mins minimum.
Once the oil starts to return you should monitor the level and drain where necessary.

Does the oil return come back to the comps or an oil separator?

Glenn's advice is sound.
Adding to His question about the refrigerant I would ask what oil are you using and has this been changed at all?
Do you have a site log to confirm what oil has been added and removed?
Good Luck Grizzly

[ben7777]

hello , and thanks , the oil will return up the suction , then into comp crankcase , they are scroll comps, so they will need to discharge that oil , and i find with scrolls they dont discharge that much unless comp is really high with oil , then they have no choice , like i say i did try to increase back pressure right up turning off the pack , , but still no return , i also put several case on defrost to allow the extra load on start up ,think maybe i could let jus one comp run alone to see if this drags it back , of course if here is oil trapped to drag back , because this i dont know ,

[ben7777]

just to add polyester based oil , seems to be all sort of synthetic with 404a

[Rob White]

.

A few points.

In your original question you said "then blow of whats in the sep"
By that I assume you mean safely isolate it and equalize the refrigerant
to the rest of the pack??

We never "blow off" do we?

As for the oil once you have established that it is short and there is
not an issue, you can pump the oil in straight from the can into either
side of the system with the oil stirrup pump.

It takes a bit of effort pumping into the high side but the good stirrup
pumps will pump it. Into the low side you could either pump it direct
to the header or individually into the comps.

Rob

.

[ben7777]

Just link it to suction once pack is off, it will go in there, then pump oil in Seperator, it's an lt pack won't have to pump against much pressure then, of course then no gas will be lost or put in to atmosphere,

[ben7777]

Just to add, so if you have a good pump it will pump into separator under pressure, , wow want one of them pumps