Cleaning Compressors

[Chunk]

Hello

I have a dual temp supermarket pack all Bitzer compressors(3 /lt 3/ht)

2 weeks ago due to some major catasrophe which is still not forthcoming in showing its head again,i lost 1 lt comp and 2 ht comps,all 3 smashed big time.

Same day changed all 3 comps,new oil,complete overhaul(possibly fixed original problem when doing this)everything ran fine for 24 hours.

Next day,losing comps on oil pressure fail.Stripped comps and found silver coloured paste coating on oil strainers.

Now problem i have,i have done an oil change and strainer clean every day for 9 days and i cannot get rid of this stuff.It is blocking the hp/lp hoses on the pressure switches and causing me no end of problems.

Does anyone have a suggestion other than removing all compressors and cleaning them out properly.I expect that if i keep changing the oil i will eventually reduce the ammount in there,but it`s boring me to tears.:o

[chillin out]

It sounds like the old comps had been destroying themselfs for some time and it's managed to get ground down parts of itself though out the system.

I would change the suction filter cores and perhaps place a large strong magnet on the inside of the comp to collect all the parts floating around.

Out of interest, have you checked the new comps for any damage?
Are you sure they are not going down the same road?

Sound nasty anyway, if you don't sort it out soon the new comps will go down.

Chillin:):)

[Chunk]

Hi Chillin

Brief history on pack.

8 years old and was not originally built for store it is in.

Problems have always been with oil.Very watery in texture when ambient temperatures are high,so you can imagine during summer months it is a pig.I have two of these packs and they are both identical,but due to these problems i have tried different methods so both packs have now got different oil delivery`s that i have configured myself to try and sort out these problems.

Both packs have had a lot of compressor changes over the years,i think 9 on one pack and 13 now on the problem pack.

As for suction filters i have only fitted them just recently and removed them last friday,they were totally clean.

The new compressors that were fitted seem to be ok at the moment.

I have made my own oil coolers out of second hand condensers from plug in cabinets and dropped the oil temps from around 120 oc to about 85oc,but as summer is coming its going to be the same old thing.

Please tell me more about these magnets.

[750 Valve]

This isn't an r22 rack is it? Those oil temps are high! (assuming you are talking recips) I think this is a hint towards the problem, what oil type are you using with what refrigerant? what oil separator is fitted? A good description of the oil circuit might help also. Also what discharge temps are you seeing?

[Chunk]

Packs are on R408a,shell sd oil(mineral),all recips as for oil seperator?no name plate,it is serviceable and is in working order.

The oil feed exits oil reciever into inline filter,then goes into a homemade oil cooler consisting of an old condenser with 2x18watt fan motors,then i have moved the feed pipe to feed the furthest compressor first(originally feeding comp1 now feeding comp6).It now feeds the ht comps first with a 20psi diff valve to then aid getting oil to lt comps.

I have fitted solenoid valves to each compressor and on the 3 lt comps i have fitted balance lines between them on the oil pots.

The above work was done due to too much oil getting into comps when they were not running.This was the original causes of the comp failures,hydraulicing on start up.

Discharge temps are around 110 oc i have no subcooling or liquid injection on these packs.

[nike123]

Both packs have had a lot of compressor changes over the years,i think 9 on one pack and 13 now on the problem pack.


Are they all mechanically destroyed or electrically as well?

With that much compressor changes it is more than obvious that system is not suitable for job, or wrongly designed, if we presume that all changes are done as it is supposed to be done. The killer is still around there.
You should send dead compressor/compressors to specialist and establish what was killed them. That is starting point in your repair, and then make logging and monitoring of all parameters who could be cause of that, and then act accordingly.

[Chunk]

Are they all mechanically destroyed or electrically as well?

They have all been mechanical failures and all dead compressors were sent back to be rebuilt.

None of the replacement comps are new and all rebuilds.

These packs were not originally built for this store,they were in storage for three years before someone said to just install them as they were probably getting in the way.

Acid tests are negative,never had moisture problems.Oil samples were sent back with dead comps for analysis.

Packs are monitored 24hrs a day by store computor which i can get parameters and running conditions from back to 3 years ago.Running conditions dont change too much,the main problem seems to be very high oil temps.

[nike123]

Packs are on R408a,shell sd oil(mineral),all recips as for oil seperator?no name plate,it is serviceable and is in working order.


For use with R408A Copeland recommends use of 50% mineral and 50% AB oil.



12. Mineral oil lubricant only, such as 3GS, cannot be
used as the compressor lubricant. Copeland recommends
the following lubricant choices :
1. A mixture of 3GS Mineral Oil (MO) and Shrieve Zerol
200 TD, Soltex AB200A, Crompton Suniso AKB200A or
Fuchs Reniso SP46 Alkyl Benzene (AB) with a minimum
of 50% AB
2. Shell 22-12 or Fuchs Reniso Triton MS 46
3. A mixture of 3G5 Mineral Oil (MO) and Polyol Ester
(POE) ie; Copeland Ultra 22 CC, Mobil EAL Arctic 22
CC, Uniqema Emkarate RL32CF, Copeland Ultra 32CC
or Uniqema RL32-3MAF with a minimum of 50% POE
4. 100% Copeland Ultra 22 CC, Mobil EAL Arctic 22 CC,
Uniqema Emkarate RL32CF, Copeland Ultra 32CC or
Uniqema RL32-3MAF.

High oil temperature could, also, be because of use of only mineral oil.

[Chunk]

Hi Nike

Just checked and oil i am using is shell sd 2212 and is a mineral/alkyl benzene oil so my post of mineral was a bit misleading sorry.

When the pack was first installed it was originally supposed to be on r404a with emkarate rl32s oil.Someone changed the specs and run it on r408a but left the oil in it.
It ran for 2 weeks with the wrong oil to start with,but mistake was rectified and oil changed to shell sd.

We are going to put a quote in this week to upgrade the oil system to incorporate a Traxoil oil level control system.

The problem i am stuck with is how to get this "paste" out of the compressors.To remove the compressors and strip them down requires cutting discharge pipes out of the way,stripping comps,cleaning and refitting back to packs.This a lot of work and as you may be aware 3/4 of my company has gone so extra labour is an issue.

I was wondering if there was a cheaper and easier way of cleaning them,if you imagine that 20 litres of oil is £100 and i am using one can on every oil change.

[bernard]

Hi

I would say your oil sep has been the problem all along,what type of oil sep is it.

Regards B

[Chunk]

Hi

I would say your oil sep has been the problem all along,what type of oil sep is it.

Regards B

I`ll see if i can get the details when i`m back in there tomorrow.If i remember rightly,they dont have any info on them as the labels have been removed.I`m pretty sure they are ac&r as i have changed the float assemblies a couple of times and got them from ac&r.

I`m fairly sure they work properly as they are not blocking or passing,its just the oil is very watery and hot.

The other pack is identical and is ticking over nicely,but also has oil temperature issues but it doesnt cause the same amount of problems.
They both have the same amount of cases and coldstores and both run at the same pressures and temperatures.

[chillin out]

Please tell me more about these magnets.
Try and get one of these magnets that they use to de-tag the clothes.
They are really strong and should collect all the bits.

Chillin:):)

[Chunk]

Try and get one of these magnets that they use to de-tag the clothes.
They are really strong and should collect all the bits.

Chillin:):)

Cheers,i`ll have a raid on Debenhams tomorrow.;)

[fowlie]

i would try and see if a temprite oil sep could be fitted as weve used these in the past as they do a real good job at cleaning out crap fromthe oil,plus you can still use the old oil reciver to help reduce the oil temps as we know how hot that 408 runs at.

[Chunk]

One final thought before i get back to playing my Nintendo Wii.

As all the compressors run extremely hot and suction temperatures coming back to pack on the lt side are -12oc and on the ht side +11oc could the problem lie with the fact that every cabinet and coldstore are fitted with Danfoss akv eev`s and i am losing a lot of suction cooling through this?I have extremely long pipe runs.

Or,not having liquid injection installed on the pack.I have two 1 5/8" liquid lines and no provision on the headers to install it,which is probably why it was not fitted in the first place.

The only cooling i have is head cooling fans on the lt comps.

[philfridge]

Maybe because its had a mix of oils :eek: that the contamination is throughout the whole system and thats why you are having these problems now. Not sure if you could fit some suction line filters after changing oil next time, but if this is the problem good luck :confused: .

[750 Valve]

Do you have an oil reservoir or is it part of the oil sep?
Sounds like a high pressure oil system - is that right?
When you say oil pot - is that an oil level control such as an AC&R type?
When you say feed one comp first, is this piped so that comp is closest to main oil line or are you dumping all oil in one comp and relying on equalizing lines to balance levels?

Just a shot here, could it be a lack of oil volume in the oil system, with those excessive oil temps it seems like possibly oil is returning in the oil circuit as quick as it is dumped in the sep/reservoir. Just as an example on a new LT rack with bitzer semi's we use an oil seperator that incorporates a reservoir and contains 10L additional oil, the comp sumps commonly hold 4L each, so we have approx 22L of oil. Same for an MT rack (we do a separate setup and rarely have LT and MT on the same rack unless they are Co2) so thats another 22L including 10L in reservoir for the MT as well.

Whats your approx oil volume in system (sumps + reservoir)?

Also it sounds like you may have a comp spitting out way too much oil in the first place creating high flow in the oil circuit and keeping the oil hot (and therefore less viscosity) as it doesn't get chance to sit in the reservoir for anytime.

If you go to traxoils all those filings will be attracted to the magnet in the traxoil, it will cause no end of troubles.

[Chunk]

Hello all.

Right to start with i was going to upload a picture,but due to the state of the plantroom i decided not to as its frightening:eek:.

I have an AC&R s5413 20 litre oil seperator,standard and servicable with no additional reservoir.

It feeds back to an oil receiver which stands above the oil seperator,it is 1 metre tall and 22" round and holds about 50 litres of oil.

The oil feeds out to a header which originally started with and fed compressor 1 first,but i used to have problems with the 3 lt compressors stealing the oil and the 3 ht compressors were not getting enough.So i reconfigured and feed the last compressor first and work back.(if that makes any sense).The start of the header is now at the other end of the pack and the header feeds to all compressors.

Each compressor has an oil regulator(pot)to control oil level in compressors.

If each compressor holds 4 litres(6 comps) and i keep the oil receiver to a third full(roughly)15 litres,that gives me 40 litres give or take.

Now i have been playing all day with Chillin Out`s idea with the magnet,but because i cant get a big magnet inside compressor easily,i used magnets tied to a stick of brazing rod and rattled it around inside the sump through the drain plug and the hole left after taking the oil regulator off.And it worked well so i shall let them run for a day or two and do it again.

With everything cleaned out and new oil in system,i run it all back up and checked operation of the compressors and found that everything was fine until lt comp2 and ht comp2 ran and the oil temperature and discharge temperatures started to play about.

I stripped the heads of of both compressors and found on comp2 that the start/unload plunger was stuck so just passing discharge and overheating,and causing foaming in the other two compressors through the balance lines.Comp 4 was ok but the oil regulator was jammed open and overfeeding the compressor with oil.With both these comps off whilst i repaired them,discharge temps were around 70oc and oil temps around 35oc.

Its amazing what you can find if you spend enough time on anything.

With a bit of luck this should have sorted it out and i can check through the other pack in a couple of days.

I had a quick read of 750`s post earlier and told the store that we are fighting a losing battle and they are getting people down to survey the site for a refit.:D:D:D:D.

A big thanks to all who have posted.

[750 Valve]

Sounds like problem solved, top effort mate.

FYI those bitzers have (or SHOULD have) a magnet inside the drain plug from factory (its part of the plug) where you remove the internal oil strainer from.

[Chunk]

Sounds like problem solved, top effort mate.

FYI those bitzers have (or SHOULD have) a magnet inside the drain plug from factory (its part of the plug) where you remove the internal oil strainer from.

Yes they do,but as they are only small magnets they only picked up a small amount.I used the bigger magnets to get further inside the sump and was surprised by the amount of metal they pulled out.

Thanks again.

[monkey spanners]

I've seen in a classic car magazine a magnet that was designed to stick onto the outside of a cars oil filter, the idea was that it would keep any ferrous metal bits in the filter. Would something like this be any use stuck on the outside of the oil line filter?

[Chunk]

I've seen in a classic car magazine a magnet that was designed to stick onto the outside of a cars oil filter, the idea was that it would keep any ferrous metal bits in the filter. Would something like this be any use stuck on the outside of the oil line filter?

Sounds like a good idea.At the moment i have only one oil filter between the oil receiver and the compressors.I was thinking about putting oil strainers just before each compressor,when i ordered all the bits they laughed at me and said"when you have paid the bill"so i gave up and went for a sleep.:D