low oil cut out, sludge, foaming, oh my!

[paul_h]

I've got a problem with a r22 bitzer compressor in a freezer, it was cutting out on low oil pressure.

Tried adding oil, it emptied the sump in about a week and cut out again.
I removed the oil separator, it was empty of oil, just heaps of sludge on the bottom. So ~4L of oil has gone walkabout in the system :o

I cleaned out the oil separator, added oil to it and the compressor, and test ran the system for a couple of days.

One thing I have noticed now is the oil return line is always hot (edit: although crankcase pressure was the normal low LP and shutting the hand valve on the oil return line didn't change the LP), and the oil in the compressor sightglass is always foaming.
If I close the hand valve on the oil return line eventually the sightglass clears and the oil level is where it should be. (this was 4 days after the last oil charge and separator clean).
However now the unit has cut out on low oil pressure again apparently.

At this stage it's probably better to replace the separator, but just thought I'd ask if anyone has any ideas on what was happening and why.

[Grizzly]

Paul.
Are you Happy with the operating pressures and the state of the evap/s etc.?
Have you noticed a rise in say discharge pressure from the norm?
Have you discounted issues with the comp itself.

My issue is the amount of oil being washed out in the first place, never mind the oil not returning.
You could have liquid flooding back, washing the oil out.
Or excessive wear, a damged piston wring etc etc.
I see where you are coming from re the hot oil line
Not trying to teach you to suck eggs!
Just talking through possible issues.
Grizzly

[paul_h]

Well I'm happy with the pressures, the compressor sounds normal and it's doing the job as far as getting the product down to temp.
Suction is warm due to heat exchanger so no chance of liquid flood back. Oil is not foamy when the oil return is closed off with the hand valve. There's no knocking sound similar to flood back or compressor wear.

There could be something wrong that I can't spot though, as this compressor has bolts and an oil pump!?
I haven't seen one for a long time, I just normally chuck and replace hermetics if they are burnt out, seized or fail pump down :D


edit: It's not leaking oil anywhere either, just making sure I've covered that. :)

[Grizzly]

and the oil in the compressor sightglass is always foaming.



Sorry this confused me a little!
What type of compressor and refrigerant is it Paul?
Only Bitzer use some clever oil level control systems, dependant upon what you have?
Cheers Grizzly

[paul_h]

Sorry, yeah, the oil has only been foamy since I cleared the sludge out of the sight glass and the oil separator has started working a bit.
Before the low oil pressure fault, the oil was never foamy in the sightglass.
And now the oil separator is kind of working, the oil is only foamy in the sight glass when the hand valve to the separator is open.
When I close the hand valve to the oil separator, the oil is not foamy at all.

The compressor is a bitzer 2n-5.2-40 on R22, but it's a custom system, no other bitzer component in there and it's just using a regular henry s5887 oil separator, check valve and like I said, just a hand valve on the return line.
No one I know down here deals with henry components, going to be hard to get parts unless there's some small local agent, none of the major suppliers have them that I know of, at least where I am. Edit: That's why I want to fix this rather than try squeeze some other brand separator with different dimensions in the really tight spot it's in which might not fit.

[coolhibby1875]

why would a suction be warm due to heat exchanger? when suctions are warm this is generly due to passing on the head, compressors rely on cool suctions to keep from overheating.
as for foaming of oil this happens with luquid boiling of in the oil, this would also explain the oil washing out of the compressor, due to liquid boiling off in the oil this changes the viscosity of the oil therefore the oil seperator canont perform its job properly hence there being no oil in the seperator,
i would hedge my bets that you have either a nrv on the discharge passing or a passing head due to the fact the suction is warm or you have liquid entering from somewhere washing out the oil, let us know how you get on!

[paul_h]

I'm not following you.
I can't see any instance of liquid getting into the compressor (is it possible from an oil separator? that's the only time it foams).
The suction isn't letting any liquid into the compressor, it's just not freezing cold due to a liquid heat exchanger (not a liquid line dinky HX, but a water HX used in the system).
System pressures are 200kpa suction and 1500kpa discharge in a 15°C condensing ambient.
I see where you are coming from, and I appreciate you don't have all the data you need to form a diagnosis, my fault though. But opinions appreciated, name it and I will do the tests and supply more info.

I had no problem pumping the system down before I removed the oil separator for cleaning and reclaiming the refrigerant in the discharge line (wasn't much in there besides 1kg of vapour, so not much liquid at all considering it's a remote condenser on a 7/8" line).
This system may have been SOG before this oil problem, not sure, but it may have other issues I'm not used to chasing, being it hasn't been even looked at for 4 years, may have not been designed right, etc etc.
So I'm all ears. The only thing I thought was OK was the compressor, but for all I know when I go back on site that may have crapped itself since the last time I was there. So I'm not discounting anything, just let me know what you want to know before I write any component off (even though I can suck eggs I'm willing to learn again :) )

[Sandro Baptista]

Paul,

Is your oil separator of hermetic type or not? If not try to see if the oil float valve is okay and/or try to replace it. It only should be open when there is oil on it so no high pressure gas (or almost) should enter to the crankcase.

I know that PECOMARK sells HENRY parts but PECOMARK as far I knoW only operates on Spain and Portugal.

I hope I have help a little.

Regards

[Brian_UK]

Sandro beat me to it.

Hot oil return line equals stuck float valve in separator allowing hot gas back to crankcase.

[Grizzly]

Paul
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[Grizzly]

Hi Paul.
Attached is some separator details regarding the float assembly and data
references.
It has just occurred to me after you cleaned up the separator etc.
You need to have pre charged the oil separator( see data sheet ).
This then sets the float valve up to return any more oil carried over from the compressor!
I assume if you only then have a manual regulating valve between the separator and compressor.
It would pay to throttle the valve to regulate the oil return.
Also with a working oil seal you should dramatically reduce the oil return line temperature.
Which with the situation you have at present you are feeling discharge gas temps!
Cheers Grizzly
Good Luck.

Sorry Paul the pdf's are to big for the forum.
I will send the via your email.

Can you pm me an email address if you would like further info Paul.
You have not got a direct link available herein!
Cheers Grizzly

[paul_h]

Sandro beat me to it.

Hot oil return line equals stuck float valve in separator allowing hot gas back to crankcase.
That's pretty much what I figured, that's why I mentioned the foaming and hot oil return line.
Though why isn't the oil coming back and the system cutting out on low oil pressure? edit: if it's leaking though it's only a tiny bit, as I said, no visual effect on the crankcase pressure really.

I mean I know how a seperator works and if the float valve doesn't seal it does let in discharge gas and doesn't build up a collection of oil to send in 'lumps' of liquid to the compressor.
Just seems wierd the oil separator went from blocked up with sludge to stuck open, and in both problems oil just disappeared into the system rather than stay in the separator.
Maybe I did something when I disassembled the separator? It's in a tight spot and maybe something got bent as I had to slide the shell off at an angle forcefully as there was a steel bracket/plate below the separator.
Also is there any way to get the oil back from the system to the compressor?

[Grizzly]

That's pretty much what I figured, though why isn't the oil coming back and the system cutting out on low oil pressure?
Also is there any way to get the oil back from the system to the compressor?
Back again.
I think I have managed to shrink the pdf's to post here?

Just check out the float assy if you feel necessary, Or alternatively just prime the system with enough oil to have the float valve open and start returning oil.
Instead of hot gas!

[paul_h]

OK the problem seems to be that the float sticks open when I fit the casing on. With the casing off, no leakage past the float valve.

There's a gauze mesh inside the case that makes it a very tight fit and the float gets caught on it and off centre.
The gauze is coming loose in a few places, so looks like I need a new separator.

[Grizzly]

Thanks for the latest update Paul.
Sounds like that sludge you mentioned before has distorted the mesh?
Not unheard of in liquid line filters but somewhat unusual in oil separators eh?
Anyway it's good that you got to the bottom of the problem.
Cheers Grizzly

[paul_h]

The mesh is a wrap around on the inside of the chamber.
Nothing flows through it, just sits around the walls to help oil accumulate.
Picture getting a cylinder and wrapping flywire mesh around the outside of the cylinder
This is the inverse, a layer of mesh lining the inside walls. Made it almost impossible to get the float assembly in and out, kept getting caught on the float and making the float stick open. Doubly so when it's such a tight angle and impossible to remove/replace the separator body over the float assembly without some twisting

I ripped all the mesh out to get it going for now, probably not even needed as I've never seen it before. Sure it would help to trap oil and let it separate from the refrigerant and drop down to the float, which is why I'm going to get a replacement separator and not leave it like that. But I had to do something to get the system going while I look around for something that fits as there's no local suppliers for henry components.

[coolhibby1875]

The mesh is a wrap around on the inside of the chamber.
Nothing flows through it, just sits around the walls to help oil accumulate.
Picture getting a cylinder and wrapping flywire mesh around the outside of the cylinder
This is the inverse, a layer of mesh lining the inside walls. Made it almost impossible to get the float assembly in and out, kept getting caught on the float and making the float stick open. Doubly so when it's such a tight angle and impossible to remove/replace the separator body over the float assembly without some twisting

I ripped all the mesh out to get it going for now, probably not even needed as I've never seen it before. Sure it would help to trap oil and let it separate from the refrigerant and drop down to the float, which is why I'm going to get a replacement separator and not leave it like that. But I had to do something to get the system going while I look around for something that fits as there's no local suppliers for henry components.


hi Paul, your right you will have to replace this now the mesh is gone, i would try and fit a temprite oil seperator, imo these are the best on the market

[oldesky]

Paul you could use a henry Helical oil separator with an external mechanical float or electronic type that bolts directly onto the compressor oil sight glass such as a Traxoil (i dont work for them). Maybe a replaceable core oil filter or oil filter with bypass valve may be advisable if the system has sludge. I would also advise fitting a check valve on the outlet of the oil separator to prevent any migratrion back to the oil sep.

[Peter_1]

Paul, unless its a rack/pack, I never installed an oil separator in my almost 30 years career.

If lines are sized correct and suction lines slopes towards compressor, oil will come back.
So, if it was me, I should check the lines and remove the oil separator. Completely.

Is suction leaving you evaporator at the lowest point? Perhaps the original tech mounted it the wrong way.
Is suction line not sloping upwards somewhere?
Is TEV feeding with a too high SH?

Be careful as you charged additional oil, it can come back at once and brake your compressor due to oil slugging. Have nice pictures of that.

If I have an inexpensive part in a system that fails and it costs several hours to repair it, I always replace it.
Especially in a R22 setup which is at least 10 to 15 years old I suppose.
The mesh inside the separator is to increase surface so that speed reduces and oil separates through and collects on the mesh.

[paul_h]

It's a custom factory built system with an oil separator, so if they fitted it, I guess they needed to because of their design.
It wasn't built on site from scratch, but as a factory all in one system
R22 isn't that old down here, used heavily since R12 was banned, we still had R22 chinese made split systems for sale until last year (maybe we still get them!). The system is probably 7 years old at the most, maybe only 3-5 years.

Yeah I'm worried about the oil coming back, that's why I ripped the loose mesh out to get it going, then going back to check oil levels a few times over the next week, (and draining some hopefully!), while getting a replacement separator sorted, bracket made up, and fitting it etc

[henrytech]

Hi Guys
i work for henry Tech in Glasgow and tend to keep a look out for any problems people have with Henry products. We have a sister company called "Heldon" based in Melbourne. get in touch with them someone will be able to help out.

Also its sounds as if its a ball float issue. you said its a S-5887 this can be fixed, and you could be able to get a replacment ball float without changing the whole unit.

Hope this helps and its not to late in the game

[Sandro Baptista]

Welcome henrytech. Nice to have a new member of the RE

[henrytech]

Thanks Mate

Also spread the word. If there are any issues with a Henry product to contact me on RE or call the UK office just ask for the engineering team.

[paul_h]

Is it worth while putting a regular filter drier on the oil return line? Some other type of small oil filter?
I've changed the oil in this compressor after the oil separator change, and it's getting pretty dark already.
Lots of sludge buildup in the new oil and the crankcase.

I'm just planning to do some oil changes over the next month, and change the main filter drier after the oil separator again, but thinking adding a filter to the oil return line from the separator would be good as well.

[lawrence1]

paul h,
I usually fit a 1/4'' flare drier to the oil return line,,,cleans the oil very well.
I think you have too much oil in the system and you should change the oil seperator or remove it completley.Have you cleaned the oil strainer in the sump?

[Sandro Baptista]

Good point Lawrence1.

[paul_h]

paul h,
I usually fit a 1/4'' flare drier to the oil return line,,,cleans the oil very well.
I think you have too much oil in the system and you should change the oil seperator or remove it completley.Have you cleaned the oil strainer in the sump?

Oil level has been drained, flushed through, level has been monitored and removed everytime the crankcase sightglass is full. So I've removed heap of oil after the top ups before changing the separator. Sump strainer has been removed and cleaned.

To tell the full story again:
No oil in compressor
Oil separator inspected, found empty of oil, but full of sludge. This was after years of operation and no one adding oil, and the oil level before this problem was normal, not overcharged.

I added oil to get the system going

Replaced oil separator, flushed liquid through the system to bring any oil back, drained off heaps of excess oil.

It was then that the compressor got heaps of dirty oil back.

Since then I've done a drier change, and drained the dirty oil out of the sump and replaced with clean oil twice. Straight away though the new clean oil gets dirty, so I'm guessing some sludge is back in the new oil separator and I want to pot a 3/8 filter drier on the return line to keep the compressor oil clean.

[Sandro Baptista]

Since then I've done a drier change, and drained the dirty oil out of the sump and replaced with clean oil twice. Straight away though the new clean oil gets dirty, so I'm guessing some sludge is back in the new oil separator and I want to pot a 3/8 filter drier on the return line to keep the compressor oil clean.

I think you're having the right procedure. Keep changing the oil and filters and until all dirty have gone...probably is dirty that is "glued" to the pipe walls.