Vilter oil loss

I have 2 systems both with Vilter compressors. One is a 450xl, single compressor, the other uses two 350 es compressors. Both systems have been in service for 20 years. Even with rebuilt or brand new compressors installed I am getting oil past the seperator(s) and not returned to the crankcase(s) I think oil is leaving more when they are unloaded and maybe in so fine a mist that it's going right thru the seperator. I am wanting to adjust Hot gas bypass to allow more time fully loaded. Both systems have had numerous problems and lots of people working on them over the years. Too many cooks? no doubt. Any body have thoughts on tuning this to minimize oil losses?

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Originally Posted by squidward

I am wanting to adjust Hot gas bypass to allow more time fully loaded.

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I would not do that. You will increase the amount of energy use by 25%-33% depending on how many additional cylinders load up.

The usual causes for oil carryover are:

Higher than normal suction superheat
liquid slugging
frequent starting & stopping
etc, etc.

Is any oil returning from the the separators back to the compressor crankcase?

OK. The system with the 450xl got a brand new compressor during the last outage. It runs 98% of the time, all year long. The suction pressure fluctuates between 61 and 68 psi or so(target of 65) I have not yet heard the hot gas bypass come on at all- on a startup the suction pressure went as low as 54 psi, still no HG bypass. We capture the history on the plant computer. Also they've been running with the evap. float level control screwed all the way in and calling for liquid out of the receiver all the time. Which of course there is none, "we just add ***** til it comes up to the level in the evaporator" I also found a broken capillary tube to the TCvalve in the coolant line of the oil cooler- Hot oil! I'll be back over ther tommorrow to adjust that float, add R-22 and see if I can get that hot gas working.

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Originally Posted by squidward

Also they've been running with the evap. float level control screwed all the way in and calling for liquid out of the receiver all the time.

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Sounds like you have a lot of other problems besides oil loss. My guess is: something else besides the compressor is causing the oil loss.

Hi Squidward;
It sounds like you have a lot of problems. I have worked on a lot of systems with multiple problems over the years and sometimes you cannot get the money to fix them all.
Iceman is correct that you have a lot of other problems besides oil loss.
My drill on oil loss from Recips is to see if oil is coming back at all. If it is not I clean the float and lines etc.
I assume your discharge temps are not too high.
You may have blown the oil separators. Do they have a replaceable element?

squidward,

It seems that low pressure receiver is starving and it calls for a liquid all the time keeping the solenoid valve busy.adjust that float and see if it liquid rise from the vessel.check regulator superheat setting, starving regulator results to low comp oil level even if you have an efficient oil separator.

Thanks, Yeah I know it has multiple problems. I am working to fix the obvious ones, and both units continue to improve..I put in a new needle and seat in the oil return float, do not have replaceable elements, don't think I have a superheat regulator. Suction temp is 41 deg.F and 65 psi/38 deg makes my superheat 3 deg. F. I'll have to check it on a hot day as well. Mostly running unloaded right now.

Well allright! It seems that you can't blame any one thing for this oil loss condition. All you can do is fix those items that you know need fixing, and when all that is fixed, system running stable, oil loss goes away!

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All you can do is fix those items that you know need fixing, and when all that is fixed, system running stable, oil loss goes away!

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Just like magic!

You will often find many small problems contribute in ways you might not expect.

My first law of refrigeration is: The problem is seldom the major piece of equipment. The major equipment is reacting to how the system operates.

People often fall into the trap of saying the equipment is at fault and most often it is not. You will usually find something else caused the equipment to break.;)

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Originally Posted by US Iceman

Just like magic!


My first law of refrigeration is: The problem is seldom the major piece of equipment. The major equipment is reacting to how the system operates.

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I think this is usually the problem; thats why I believe there is no replacement of a good knowledgeable operator! A operator that knows his system inside and out is worth a whole lot in my book.:D

I would agree with you nh3wizard. I keep seeing people who think the equipment is not operating properly and want to adjust it.

Here is a scenario: system is perceived to not be cooling adequately. Result? Adjust an expansion valve or add more refrigerant.

Answer? More training and education is required. That is not a slap at anyone. This is a complicated industry!

The more interesting problems are where someone tries to force the system to operate the way they think it should. I'll bet you have seen this also.;)