shaft seal failure

[modvalve]

Hi there I removed a shaft seal out of a Sabroe VMY screw and got it reconditioned, now 6 months later it has failed again. On inspection the shaft seal is perfect but the o rings have lost their shape causing leakage also removed the coalescers from the oil seperator as they were changed 18 months ago and same problem. The coalescers were a genuine Frick part. No one can tell me why the o rings are failing. Has anyone else had a similar problem. The compressor runs on Mobil arctic shc 226e fully synthetic oil and ammonia is the refrigerant. The setpoint is 2 bar

[RANGER1]

Search forum for HNBR and see what you think .

[modvalve]

Hi ranger sounds like I need the HNBR seals. James Walker supplied some genuine neoprene seals for the coalescers and they said that Mycom use a special type of nitrile in their o rings I'm guessing this is the HNBR. I think the crowd reconditioning the shaft seal were going to talk to Mycon about their o rings so hopefully this will sort the problem out

[RANGER1]

I think you will find HNBR hard to get in sizes you want .
Probably have to come from UK .
I have sourced a few fron jci Sab 202 that suited my purposes at the time .

[josef]

Hi, this problem and I had the compressor VMY, 3x claims in Sabroe.
Coalescer Frick?, I noticed for some time a problem with "O" ring is deformed and has no durability, up to 5000 hours.:mad:
Perhaps the manufacturer develops the best materials:o

[modvalve]

Couldn't get shaft seal o rings in hnbr as Mycom dont have the correct size so have gone with neoprene. The shaft seal people are now saying that they purchased some o rings from Taiwan and werent of high quality that is why the failure after 6 months so we will see how long this lot last:rolleyes:

[ref717]

Neoprene rubber has excellent chemical resistance against ammonia but has moderate to severe effects with any refrigeration oils.,on the other hand using Nitrile rubber has excellent resistance against oils but has moderate effect with ammonia. I've read in a book that ammonia compressor shaft seal o-rings are manufactured with special composite rubber materials to withstand this cross-effects with ammonia and oil.

[TXiceman]

Anytime you start going aftermarket and rebuild on seals, be very careful that you get seal elastomers that are compatible with the Oil as well as the refrigerant. It sounds like the wrong elastomers.

ken

[mbc]

First You have to set coupling ( between motor and compressor ) in very low tolerance .you can find
In manual book rang of that.
You can find in market O ring if you got size of that (( I used and checked more than 50 times ))
Only O ring should work in hydraulic oil ( in market they say O ring For brake oil )and you can test it by putting that in hydraulic oil for one week ( if you can heat it up to 50 c it is better) do not use heat resistance O ring ( red color O ring)
Because in NH3 these O ring ( red color O ring) is not good and after 6 month they lose flexibility and become hard as same as carbon