Adding Oil to a pair of copeland Scroll Compressors

[Grizzly]

Hi Guys.
I have a site with a chiller which has 2 Copeland scroll comps.
Which have a sight glass each and a 3/8 copper oil balance line between the 2 comps.
Both are low on Oil.
Can I get away with adding Oil via the suction line. As there is a Schrader fitting on it just down stream of the comp suction port.

On other sites these lines have been Moded with a Schrader fitted into the balance line.

Only that would mean shutting the chiller down and a gas recovery.

What's recon Guys?
Grizzly

[Brian_UK]

Reading up on these scrolls would suggest that a non-standard oil balance line has been fitted as there should be a schrader valve fitted.

Assuming that you mean your suction schrader is upstream of the suction port then you should be ok to add oil through it.

The motor is designed to run fully flooded if need be and the suction port is well down in the shell so any oil should drop out of the suction vapour as the velocity drops entering the shell.

[Grizzly]

Thanks for your help Brian.
I should of said this balance line is on systems which have 2 or more comps on the same system.
What tends to happen.
Is when a comp starts it will tend to draw across the oil from the stationary comp.
So you can have on a 2 comp system. the running comp with a full glass and 1/2 a glass on the stopped comp.
This appears to be quite common now and I see it on Bitzer scroll systems as well.

As you can imagine with the Schrader port (For Oil Top Up!) no longer being in place.
Topping up with Oil is a dilemma.
Hence my question.
Grizzly

[Rob White]

.

Hi Griz no problem with adding the oil through the suction, the scroll part of the comp would never see it because of the design. Pumping it down might encourage the oil to travel a bit easier (faster) but you should not have a problem, other than making sure you know where the oil is disappearing to at the other end.

:)

Rob

.

[Grizzly]

Thanks Rob.
Your reply made me smile.
Sign of a good engineer asking where the Oil is?

In this case there was I believe? A pipe failure dealt with by others!
Logging the running parameters tells me we don't have a Oil Logged Plate heat exchanger.

So I assume the Low Oil was not rectified along with the repair?

Thanks for backing up what Brian had said, I wouldn't think twice on other styles of equipment.
The smaller scroll stuff however was worth asking the question.

Because I have learned something else which I bet others did not realise either.
Thanks Guys.
Grizzly

[chemi-cool]

On scroll compressors, suction is actually connected to to sump so every drop of oil will go directly down.
You have mentioned the type of refrigerant cause some of them carry oil better then others.
low suction pressure mean slow refrigerant flow and therefore bad oil return.

Have fun.

[mbc]

Hi

You have to find reason of why oil is not coming back
If it was full before .
In new system we have to add oil
Amount of oil is cerculing in system