417A problem?

[Virus]

Hello,

I am currently on a ship running a chilled water system using 5 hermetic Copeland ZR19 compressors. A couple of years ago the refrigerant got changed from R22 to 417A. The system is about 10 years old and in the last couple of years we have changed out 3 of the 5 compressors due to high hours. Last compressor was done about a year ago and then we also had the 2 heat exchangers replaced and cleaned the pipework.
Now when leaving a shipyard last month this compressor shows a fault and stopped running. On Inspection I found that when reset it would run for about 1 minute but releasing the internal pressure valve constantly (Not even close to reaching high pressure trip) until going into fault mode. I removed the filter for inspection and found that it seemed to be full of oil.
I had a couple of days in port where I after much effort finally got a refrigerant engineer to come have a look at the system. He deemed the compressor dead, luckily I carried a spare so I got him to install the new one. After installation of the new compressor the exact same thing happened with the internal release. The refrigerant engineer told me that his believe was that there was a oil lock in the system. Unfortunately we did not have time for him to do more investigation.

Now when I looked on the Copeland website for some support I came across an article stating that Copeland does not support the 417A due to unknown oil separating capabilities and recommends 407C as the R-22 replacement.

Now my question is, do you believe the 417A has caused the grief with the compressor?
And what will I need to change in my system if I decide to go with the Copeland recommendations?
Can anyone give me any recommendations on where to move from here?

Thanks,
Jauma

[Rob White]

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Scroll compressors don't mind a bit of oil, it does depend on
just how much was inside the compressor.

Where did the oil come from?
Is there now a reduced amount of oil (now the other comp has been removed)?
Does the system have an oil seperator fitted?
Do the compressors have individual oil level indication?
Do the compressors have oil management (oil floats) fitted?

If 2 comps failed for identical reasons then it is not the comp
that is at fault but the system.

Is this compressor first inline, second, third or fourth?

What cycles the compressors on and off and are they cycled
so the average out in run hours or is it always comp 1 on and comp 4 off?

Loads of questions I feel, but if the system has been running ok for the last
year I can't see why it should instantly be the refigerants fault.

Look at the basics and see what has changed since then.

Regards

Rob

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[r.bartlett]

Can you get on the discharge pipe for a pressure reading. I suspect you may not have the necessary equipment or training as you got an engineer on board to do it for you..

can you post some pictures as that really helps here

[Virus]

Hi rob and thanks for your reply,

The only place the oil could have come from is the compressor, it was missing a bit of oil when I removed it.
There is no oil separator externally on the system.
All of the compressors have a sight glass on the bottom. The compressors are all independent units, and this is the fourth inline.
The replacement compressor never got started properly because when it was being gassed the internal valve started releasing.

The compressors are started by a sensor on the chilled water circulation and the run time is set manually by choosing the lead compressor.

The only reason I was afraid it could be the refrigerant was because of the Copeland website where they warn you from using the 417A. However you are correct the system has been running fairly good with that gas, so it shouldn't really be that.

[Virus]

You are correct r.bartlett in the fact that I am not well trained in the subject. I would say my knowledge is purely basic from my marine engineering college and experiences with these systems which is as I say very basic.
The problem I am having at the moment is the difficulty of getting an refrigerant engineer to look at the system, so I was hoping to get some help here in troubleshooting it before the next chance i can get an refrigerant engineer on board so we can use the time better.

I had gauges installed on the system by the HP and LP on the compressor when the gas got changed so I can tell you that the pressures for the short time the system runs and the internal valve is passing is around 10 bar on both sides fluctuating rapidly around 2 bars. The normal operating pressure is set up at HP17bar LP 2.5bar.

IMG_0094.jpgIMG_0101.jpg

[al]

Virus

Was the oil changed to synthetic with the 417, are there discharge non return valves on each compressor, it could be these are buggered and would kill a scroll pretty quick!! Where are you sailing, tropics or europe?

al

[Virus]

Hi Al,

Yes the oil was changed and the compressors we have replaced came with synthetic. There are no no-return fitted on the HP.

Sailing in med at the moment around Italy. temperatures still quite tamed so we are alright for the moment

[The Viking]

I'm thinking that as the new compressor fail on startup there is no way the oil is to blame...

Something must be completely blocking the discharge line.
Is there a manual valve on the discharge line where it is connected to the compressor? Open?
Any non return valves in the discharge line?


But as been said before, photos or line diagrams would help.



.

[Virus]

Hello Viking,

There are no valves in the line except for the solenoid valve on the LP line.

There are photos in my reply to Mr Bartlett above, I will draw a quick diagram and post it.

If the dischage line would be blocked should n´t the HP trip shut it down?

Thanks

[The Viking]

OK,
Looking at those photos there are rotalock valves connecting the pipes to the compressor.

If you remove the black plastic cap from the one on the discharge line you will see a valve stem.
If that stem is fully wound in (like a shut water tap) it will close the discharge line.
If it is fully wound out (like a fully open tap) it will open the discharge line but close the connection to the black hose.
Normal running position for these valves would be achieved by first fully winding it out (anticlockwise) and then wind it 2 turns back in.

Depending on how and where the HP switch is connected that might also be isolated (shouldn't be possible but...). More likely, the HP switch is faulty.

There are only so many things that will open a compressor's internal pressure relief valve, problem with the oil isn't one that springs to mind.

On the other hand, why is the conclusion that the internal PRV has opened?
Any chance that the compressor isn't pumping in the first place?

These compressors are sturdy but they are not bomb proof, if enough liquid refrigerant enters the compressor the scroll and/or the valves will be smashed to pieces. It might still rotate but it would no longer pump refrigerant.

Excessive amounts of refrigerant might enter the compressor as a result of various component's failure, the TEV being the main suspect.



.

[Virus]

Sorry, forgot to count these in, but yes these are open and the HP is connected before the valve.

I assume it is the internal relief valve because of the short pressure build up and pulsation when the compressor runs. is there a way to test the if the compressor is damaged? I don know how this much liquid would have gotten to this new compressor.

thanks

[Virus]

Also I might test the HP switch on another compressor later just in case.

[monkey spanners]

Sounds like a blockage or restriction in the discharge line, have seen a vibration eliminator close up inside to give similar problems. Also on a reciprocating comp i've seen the valves break up and block the discharge line after it failed.
Has the shrader core been removed where the hp switch line goes on? (assuming is on the rotalock stub and not the valve proper)

Is the compressor running the correct rotation?

[Virus]

The valve was swapped from the old compressor which had the core removed already.

The rotation is correct, just in case I double checked the connection and they are all good.

What would you recommend as the next step? I am a bit worried that the compressor may be broken, is there any way to test that?

[Virus]

This beautiful drawing i made of the system and as you can see it is a textbook system.

TG system.jpg

[Virus]

Sorry, was in too much of a hurry, screwed up the order there. Of course it is filter, solenoid valve and then expansion valve... and not the other way around

[Virus]

So... I spoke with Copeland UK today and they seem to think that there is a block somewhere on the suction side of the system, most likely oil. The reason the compressor does not build up pressure is they say because it needs the pressure on the suction side to create a seal between the HP and LP side, and now it is merely recirculating the gas internally.

The reason for the extra oil- in the system they say could be because they deliver the compressors overcharged and if it is a new system the extra oil will go around the system leaving a film of oil around it. Our system all cleaned out when the new compressor was installed but I guess maybe some oil needed to be discharged from the compressor before fitting it because our system is quite compact... I don´t know. Has this kind of block ever happened to one of you? What needs to be done? And what are your thoughts on Copelands explanation?

Thanks

[The Viking]

Copeland's explanation is valid but you told us there was a 10bar pressure on the low side?

[Virus]

The gauges show 10 bar on the LP and the HP when it runs, fluctuating 8-10bar.

[r.bartlett]

The valve was swapped from the old compressor which had the core removed already.

The rotation is correct, just in case I double checked the connection and they are all good.

What would you recommend as the next step? I am a bit worried that the compressor may be broken, is there any way to test that?

Rotation is not dependant on them being in the right order. These compressors are rotation critical. However I suspect your refrigeration eng would have checked this already..

Close the suction valve on the red handle and the low pressure should drop down quickly. If it doesn't then the comp is not pumping..

[monkey spanners]

The valve was swapped from the old compressor which had the core removed already.

The rotation is correct, just in case I double checked the connection and they are all good.

What would you recommend as the next step? I am a bit worried that the compressor may be broken, is there any way to test that?

In your pictures it looks like there are two copper lines run from the stubs on the compressor that the valves screw on to. The lines look like the go to the pressure switches. These connections have had shrader valves in in every large copeland scroll i have fitted. These are the ones i was on about, not the connections tee'd on the valves which look like the go to the gauges.

Measuring the running current might also give an indication as to if it is not pumping or loading up till the internal safety lets by.

[al]

V, as stated above, if the compressor rotation is wrong it will sound rough and not generate a pressure differential, it would be worth swapping two phases and doing a quick test to verify. If the compressor is buggered then it is most likely a discharge blockage, remove the refrigerant and use nitrogen to test for blockages, or alternatively pull into the beautiful city of Cork (you can park on the quays, independence of the seas fits so you should be no bother) and i'll check it for you)

al

[r.bartlett]

V, as stated above, if the compressor rotation is wrong it will sound rough and not generate a pressure differential, it would be worth swapping two phases and doing a quick test to verify. If the compressor is buggered then it is most likely a discharge blockage, remove the refrigerant and use nitrogen to test for blockages, or alternatively pull into the beautiful city of Cork (you can park on the quays, independence of the seas fits so you should be no bother) and i'll check it for you)

al

From what I can see the guages are connected to the comp service valves which show 10 bar so where is the blockage?

[al]

RB
How do we know the gauge is accurate, and not gone all the way round the dial for example. The examples i've seen of such quick failures all related to discharge blockage, although NRV's were present.

al

[The Viking]

Not to mention the fact that the gauge shows 10 bar now, when we all agree the compressor isn't pumping.

Nothing to say it didn't hit the stop for a fraction of a moment before the compressor failed.

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