York YCAV fluid chiller MTS Screw compressor

[Auscold]

I have been asked to look at some York MTS 24S AA D46/200 semi hermetic screw compressors by a colleague of mine the screw compressors are fitted to a York YCAV 0569 fluid chiller.

I usually work on Industrial refrigeration plants mainly Ammonia and chemical plants and I overhaul large Reciprocating and Screw compressors frequently so my colleague has asked me to check out the compressor for him as it was tripping on high current when it went to full load.

On first appearence the compressor looks similar to an XJS 120 frick with some modifications to it.
When I spoke to Frick and gave them the model, serial and part number of the machine I was told by them that the model did not show up in thier system at all.

I removed the bearing cover and performed a thrust check on the machine and found the thrust clearence to be .040" different between the two rotors!!!!!! Dead machine in my books the compressor has only done 28,000 hours

Does anyone know the recommended inspection/service interval for these screw compressors?

My colleague looks after 6 of these chillers so he wants me to do a thrust check on all the machines for him to check the wear in the compressor bearings.

I am looking for any information possible for these compressors and the chiller itself.
A parts diagram of the compressor would be very useful so I could order new o'rings for the back bearing cover of the machine and new bearings if I find wear in them.

Any help would be greatly appreciated

Thanks

[r404a]

dont think these things will be field servicable

[york56]

dont think these things will be field servicable

I would tend to agree anything could be taken apart but I can tell you that I have never repaired one in the field nor have I ever seen any documentation for repair everyone that I ever removed due to failure was sent back to the factory.

[Auscold]

r404a and york56 thanks for the heads up as I was beginning to think nobody works on these in the field.

But I really don't no why you wouldn't, they are a very simple machine with less components than an XJS 120 and I have replaced bearings on them in the field.
I am just on a remote site with a fully equiped workshop and it would be very easy for me to take the machine out of the chiller and repair it on a bench in the workshop then re-install it before it even reached the JCI factory!

The decision has been made to replace the machine with the large end clearence so I am going strip it down and see what makes it tick!

Do either of you have any idea what the recommended run hours and or starts for this type of screw is?
In your experiences over the years what sort of run times have you seen on these compressors before needing to exchange them?

Thanks for your help it is greatly appreciated!

[york56]

Do either of you have any idea what the recommended run hours and or starts for this type of screw is?
In your experiences over the years what sort of run times have you seen on these compressors before needing to exchange them?

Its a fairly new compressor that they are using now replaced the DXS style screw everything now is the variable speed compressor as for hours or starts that would depend on the application its being used for , I have seen more electrical failures than mechanical but not to say the tides won't turn , I believe that run conditions and the way its being maintained have a lot to do with it excessive starts and short cycling never was a benefit to any machine. Most guys in the feild don't have the resources to pull that compressor and put it on a bench to work on it like a gentleman like yourself everything today is hurry up change it out and get it back on line.

[Auscold]

work on it like a gentleman like yourself

LOL!!!!!!!!
I have been called many things before not usually a gentleman!
We are under plenty of pressure to get the job done and back on line as well and it isn't so much about having resources but more of a remote location issue so we can't just get a compressor that easily and the customer is a lets fix it on site type of guy. I can assure you I would rather do this in a nice clean shop if I could were just doing what the customer wants! I'm sure you have been there before.
You mention the old style DXS compressor that the MTS replaced could you purchase replacement bearings for this type of compressor through York?
You don't know where I could get a copy of a parts manual for a DXS style compressor or know what model chiller they were fitted too so I could try and contact JCI and try my luck.

I don't usually work on York chillers so these types of compressors are new to me.
From what I have read the DXS type compressor used had a varible slide valve in them but no VS drive and the new MTS compressor has done away with the slide valve and uses the VS drive for load variations.

Thank you for taking the time to enlighten me on York equipment.

[Dallas Duster]

Do starts really matter in a VSD machine like this?

[ga1279]

Auscold- Can't say to much for York, but I do have experience with screws that being Trane, Carrier, McQuay, Hitachi and Howden and the one thing they all have in common is .000" for thrust when manufactured. Some will allow .001"- .002" max before changing bearings. If you looking at what happens between the lobes you can understand why. You are talking ulta tight spacing between the rotors and as the gas is getting compressed the axial forces tend to push the rotors apart axially (if there is such a word) so at .040" thrust I have to say is a major issue. Good luck- GEO

[Auscold]

Hello GEO,
I agree with you on the fact that the York screw is in pretty bad shape, This is the first time I have taken one apart but I have rebuilt many Howden, Mycom, Stal, Grasso and Frick screws before and for a little machine like this to have 0.040" clearence my guess is it has ground it's way into the housing.

The biggest problem I am having is York/JCI will not provide any information or parts for the MTS screw!?!?!?!?!?
York is very different from Frick I have never had any trouble getting a parts diagram/list and parts from Frick or Mycom, Howden or basically any of the Industrial companies before.

Hello Dallas Duster,
I have been told starting and stopping is always a bad situation for high speed rotating machinery because your taking a machine from a stand still and spinning it so you are exerting all sorts of forces on the rotors, bearings seals etc.
Even though a VSD removes some of the violent force from the old style starters a certain amount of extra force remains.
Until the machine reaches certain critical speeds and temperatures greater wear will be present.
A screw compressor that you turn on ramp up to full load and let run for 60,000 hours will almost always show less wear than a screw compressor you start and stop 3 times a day and has a varible load that has only done 30,000 hours even with a VSD fitted.

Thanks for your input

[Screwit]

Auscold,

Can you please update your profile with an email address so I can send you some of the information you are requesting.

Sorry got it, going blind in my old age.

[york56]

http://www.cmpcorp.com/ac_compressor...placement.aspx

You might try this company they might be able to help you out with the info. that you are requesting.

[Auscold]

http://www.cmpcorp.com/ac_compressor...placement.aspx

You might try this company they might be able to help you out with the info. that you are requesting.

Thanks York56 I will look them up and ask some questions

[Auscold]

York56,
I spoke to the people at cmpcorp but unfortunatley they don't deal with the MTS screw compressor and said they don't really deal with the DXS either.
Any other idea's?

I have had the chance to strip the MTS down and it has chewed into the suction end pretty bad but there isn't much to the bearings in them very similar set up to an XJS 120/151 Frick so I am off to the local bearing supplier to see if he can match them up and then take the old o'rings to a supplier I use all the time and try my luck there as well.

I found the main radial load bearings where in very good condition very little wear at all but the male rotor outboard thrust bearing was tore up pretty bad probably due to the high head pressure the chiller runs with all the time.

If I can get the bearings off the shelf I will start doing thrust checks in the new year and go from there!

Thanks for all the input from the other members.

[york56]

It appears that the MTS compressor is a York OEM compressor unfortuately they must have a specific compressor rebuild facility that does only there remanufactures which unfortuately makes you go back to them only if they won't provide info. or parts break down info. I have looked all over in regards to this.

[Auscold]

It appears that the MTS compressor is a York OEM compressor unfortuately they must have a specific compressor rebuild facility that does only there remanufactures which unfortuately makes you go back to them only if they won't provide info. or parts break down info. I have looked all over in regards to this.

Thanks for looking around York56 you've been more helpful than the JCI service center I have been dealing with.

I have to agree with you in regards to York wanting to do the work themselves because I have spoken to the parts people a few times and they just don't/can't help me out.

Looks like I will just have to make my own parts manual then!

Thanks