Liquid slugging problem

[Andrey]

Hello everybody,
Does anyone know where can I get some information about " liquid slugging effect " in refrigeration compressors. There is a problem with it, and we can't find something to figure out what problem is. We have 5h120 A194 CARRIER model compressors, Gas R -22..

[US Iceman]

Hello Andrey,

Can you provide some information on the nature of the problem?

What type of system do you have this problem with?

Does the liquid slugging occur during specific times?

There are many things that can cause liquid slugging, so if you can provide more descriptions of the system and it's type of operation we may be able to help you.

[old gas bottle]

you need to stop that quickley as it will kill that type of compressor very quickley,it will thin the oil and wash it into the system,put strain on the pistons/rods and crank,and bingo,

[Andrey]

We got it suddenly, I mean the problem. We have some 5h120 Carrier compressors. Suddenly they begun to noise, when we opened the compressor we've found too much burnout in it. We checked the oil no acidity just lots of parts different iron. We didn't change something in the system ( time or period of defrost etc.). I didn't notice any liquid marks. So I just want to know more about that problem. Is there any specific marks that can help me recognize "Liquid Hummer" earlier then it'll happen..

[Andy]

We got it suddenly, I mean the problem. We have some 5h120 Carrier compressors. Suddenly they begun to noise, when we opened the compressor we've found too much burnout in it. We checked the oil no acidity just lots of parts different iron. We didn't change something in the system ( time or period of defrost etc.). I didn't notice any liquid marks. So I just want to know more about that problem. Is there any specific marks that can help me recognize "Liquid Hummer" earlier then it'll happen..

Hi Andrey

Liquid hammer is the sound that the compressor makes when it is trying to pump liquid, a knocking sound

When stripped you will see water marks on the piston, where the solvent effect of the liquid has cleaned parts of the pistons a bit like water marks (droplet sized clean areas on the pistons).

Kind Regards Andy

[Andrey]

There are not any water marks on the piston or so, just burnout on the bearing and knocking sound. :-)

[Andrey]

I shot some pictures, where can I post it ?

[US Iceman]

When you reply to the thread using the Post Reply button you will see the following on the new window.

Additional Options:
Manage Attachements

A window will appear. From this window you can search on your PC to find the pictures you saved. Select one of the pictures on your hardrive and click the Upload button.

Do the same for each picture you want to upload (limit of 5 I believe).

When you submit your reply, the pictures will appear as thumbnails below your message.

[US Iceman]

Andrey,

You asked for ways to identify liquid slugging. The easiest way to check this is before the compressor starts to make sounds.

I like to use the discharge temperature as a first check. If the compressor has some liquid (even a little bit) in the suction gas, the discharge temperature will be a lot lower than when the suction superheat is within normal ranges.

Another way is to measure the discharge superheat. If the discharge superheat begins to rapidly decrease, the only way this can happen is if the compressor has some liquid entering it.

As the liquid in the suction gas begins to reduce, the discharge superheat will increase.

This is similar to suction superheat. If the suction superheat is zero, you have a very good chance that liquid will/or is, entering the compressor.

[Andrey]

Thanks for your advise, there are some pictures from the compressor :

[Andy]

Thanks for your advise, there are some pictures from the compressor :

Hi Andrey

on picture number 3 I can see a very badly damaged bearing. Looks like the compressor ran with little or no oil pressure. Possibly the compressor ran low in oil and the oil differential safety did not stop the compressor.

The knocking sound was probably the slap or clearance between the shell bearing and the shaft allowing the connecting rod to move about on the shaft during compression.

Kind Regards Andy

[old gas bottle]

looks buggered having a hard life,like andy said,oil dilution,poss pump problem or lack of oil changes,if its running a coldstore ,is there frostback on the suction line either on start up or while running,somethings killed it,give us a clue about the system,one thing for sure it needs a complete overhaul now not just a set of shells.

[Andrey]

Firstly thank you all for your reply !
As you can see from the pictures there are not proportion damage, we have four 5H120 compressors, and of course there are not problem with the oil pressure(at least it seems to be 45-60 psi differential pressure, we have all kind of defend). I did some measurements and I found nothing suspect I mean superheat problem. What I have to tell that this compressor has been repaired after the same problem, and worked only 150 hours that's it. I'm posting some more pictures from the same compressor.

[Andy]

Firstly thank you all for your reply !
As you can see from the pictures there are not proportion damage, we have four 5H120 compressors, and of course there are not problem with the oil pressure(at least it seems to be 45-60 psi differential pressure, we have all kind of defend). I did some measurements and I found nothing suspect I mean superheat problem. What I have to tell that this compressor has been repaired after the same problem, and worked only 150 hours that's it. I'm posting some more pictures from the same compressor.

Hi Andrey

how does the oil get to the small end bearing, I don't see a hole in the top most shell to allow the oil to flow

Also the wear on the shell is oil at one point, leading me to believe that the crank shaft is oval.

Kind Regards Andy

[costa]

Hi Andrey,
I took your advice and registered .
I am also looking into your problem as you know.The most suspicious clue is I think the hole in the oil filter.What you have is not slugging (the vaLves were not damaged just the bearings.)
I'll talk to you tomorow.
COSTA

[costa]

Andy,
The small end bearings don't get oil from the crankshaft on the 5h carrier compressors
they are lubricated by oil thrown up by the crankshaft
Costa

[refteach]

The bearing wear looks like it increases up to the peak loading point of the bearing, as the connecting rod goes up pressure increases until the discharge valve opens, being at top dead center it is at the peak loading point. If this is combined with a non compressable (liquid refrig or oil) above the piston it would increase the pressure.

Another potential cause could be a lubrication film thickness problem, the oil could be the wrong viscosity, temperature, oil pressure or have the presence of liquid refrigerant in it. This will also result in this type of failure.

[Larry2]

You can't just throw new bearing caps in and have it be happy. If this were a car engine, you would have a machinist correct the crank to a freshly polished undersize surface. I expect the same thing applies here. If the piston pin has excess clearance, that will transmit mechanical abuse to the new bearing. You need to "blueprint" the assemblies, not just fit new caps.

[rbartlett]

Marc wrote this a few years back...

http://fridgetech.com/articles/recipfailmodes/

Cheers

Richard

[Azi]

Hello every body
i am new in this forum. i am basically a process engineer working in oil and gas industry. i have experience on working R22 refrigeration sysytem. if am of any help to any body will be a pleasure for me.
azi

[refteach]

Larry2 is right, the babbit that is on the bearing halves is only thousands of an inch thick and is not meant to be a lubricant only a place to embed dirt and wear particles so they do not score the crankshaft, by the looks of the bearings the babbit it gone and you are down to the steel backing. Not good for the crankshaft. Definately measure up the journals and get them reground undersized and use the appropriate under size bearings.