Printable View
I am having a problem with a Howden XRV compressor leaking around the shaft seal. If the compressor is shut-down for any longer than 8 hrs it starts to leak ammonia. When the compressor is in operation it does not leak ammonia or oil. I have replaced two seal in this compressor for the same symptom everytime. Anyone else have this problem?
Lots of possibilities:-
alignment, o/ring compound, thrusting, oil grade.
I would look seriously at alignment, I prefer Lazer alignment, zip /zero mis-alignment.
Any thrusting will kill o/rings. Motor bearings should C2 or C3 rated.
The shaft seal while running is pressure feed with oil so all systems are fine,stopped the seal box drains and any suspect o/rings will leak, and those stupid wedge rings.
Start with alignment checks
Alignment was the first thing I checked. I am within .001" everywhere. I talked with Howden and they are suggesting a check valve in the main oil injection line to stop the oil from draining back in the off cycle. This comp is a replacement from the original one on a FES 315R package. The original comp did not leak. Howden said that this comp could be a looser fit???? I am not buying this. Every seal I have got from them for this comp has been different. It seems to me they are searching for a solution to an ongoing problem.
A loose fit. What crock of shyte, an admission of incompetency.
The worlds best screw compressor manufacturer has dropped the ball, so to speak. I am very disappointed
Hi
have had the same problems with both XRV 163 and 204 running on ammonia.
In the end after trying different types of original shaft seals we had to find a supplier of o-rings, and got them a little thicker than the original one.
Its maybe a little early to say that the o-rings is the problem, but after 4-5 months on 5-6 compressors we have not registred any leakage in the shaft seal yet.
Hope this help....
Interesting post this coolcmt!Quote:
Originally Posted by coolcmt
Do you happen to know what the supplied "o" rings are made of?
Magoo.
I have to agree, it seems as if most of the "good guys" are being influenced by the Bean Counters now!
Ice.
Interesting one this.
Can you keep us posted?
Cheers Grizzly.
me to The last seal fitted has held out for about 5 -6 months but like has been said the last seal fitted was different to the origional one I will find out the "o" ring material and let you guys know but I think it was NitrileQuote:
Originally Posted by coolcmt
Hi guys!
The material i HNBR 70.
It seems to me that the original seal is a little "loose fit", not much resistance when you push it to the correct possision.
With the new o-ring it feels tighter.
We ordered 3 different sizes, the smallest is for the stationary seat, and we have used the biggest one in the seal.
XRV 163:
51,00 X 3,50 mm
53,00 X 3,50 mm
56,00 X 4,00 mm
XRV 204:
60,00 X 3,50 mm
63,00 X 3,50 mm
66,00 X 4,00 mm
The shaft seals are not cheap to buy so its worth trying to change the o-rings...
Again, hope this info helps you....
As stated in the previous post the material is Nitrile again as stated expensive at £2500 for a refrurbished seal :eek:
Isn't HNBR a special type of nitrile not the standard ?
I would use nitrile or neoprene preferably .
I there's a post from a mycom man showing all the compatabilities as synthetic oil is a bit prone to shrinkage .
Most industrial companies in Australia would refirbish seals for a fraction of 2500 pound .
If it was a standard lap with new "0" rings it would be approx $300
Yes Nitrile and Butyl mixture, but a refurbed seal comes with more than just a few new "o" rings but £2500 is still very expensive.Quote:
Originally Posted by RANGER1
Take it or not I have used a company called Latte international for years they can knock spots of the OE suppliers in both price and support
;)
Canadian Ice.
What oil are you running in these compressors?
We are running a Reflo 68A which is a hydrotreated oil. I think you guys run it in the US also?
We are running Reflo 68A oil. This is a hydrotreated semi-synthetic oil. I think it is available in the US also. We use it all the time.
Hi Canadian Ice,
from memory way back PetroCanada had a problem with certain types of O/ring material and the Reflo oil range. Cannot remember details though. Email there technical department
Sounds like you have a thrust bearing problem, Likely worn, how many hours since overhaul? Alignment doesn't matter when you're shut down.
Thanks
ben wolfgang
The screw only has 7000hrs on it. It was a new screw not rebuilt. Howden inspected one of the failed seals and said it was a heat problem. Machine has a thermosyphon oil cooler. Oil temp is never an issue. Still searching for a solution. Magoo may be right. Reflo oil seems to be hard on o-rings.
Thanks
Hi Canadian Ice.
did you contact PetroCanada ?
Hi canadian Ice.
How did you get on with Petro-Canada and the Reflo specs, I have tended to be very wery of using in low temp applications. teded towards CPI 10096-68, a similar product without the greif. Another is the FMC 68 semi synthetic, good for vacuum range boosters/ two stage. Compatible with the Mobil SHC range ( super expensive down here ).
Let us all know how you resolve this problem.
personal stuff sorry
Have had trouble with a particular seal leaking , so installed HNBR "O" rings .
They appear to be a better "O" ring from what I read on specification .
Originally develoed for R134a I think , but suitable in Ammonia and all types of oils .
Temp rating up to 150 C as most "O" rings are about 100 C ie neoprene and nitrile .
Time will tell as seal faces are silica carbide on silica carbide so think localized heating in this case over 100 C .
Howden I think are using silca carbide on carbon in WRV anyway .
Hi Guys:)Quote:
Originally Posted by RANGER1
I have worked on a few Howdens over the years, some XRV. The earlier XRV compressors had their casings made in India. Failures were frequent.
I understand that the casings are made else where now and the problems have stopped.
One issue Howden have is the orings they use in the seals shrink when in contact with synthetic oil. They should be supplying HBNR oil rings, but sometimes they forget:mad: or the package builder forgets to specify the correct orings
Refrigeration compressors are only a small part of what Howden do so the standard compressor will have orings suitable for mineral oil only.
Change the orings to HBNR in the shaft seal and use a CPI oil with the seal swell additive in it to condition the seals that you can't easily change and have a word with Howden through your package supplier.
Hope this helps:)
Andy
Guys,
If I can please clear up some of the misunderstandings in this thread.
Howden produce 'bare-shaft' compressors for OEM's, the end use of the compressor is very rarely know to us when the compressor is manufactured. All standard units are shipped with a specific grade Neoprene o'ring, selected as 'the best fit' for all applications. What is becoming clear over the last year or so is that the many combinations of synthetic oils and refrigerants, and their unknown constituents, are having different effects on the Neoprene. We can now offer seals with different grades of Neoprene, HNBR, or Perfluoroelastomer (Kalrez). What has become obvious is that there are no clear guidelines.
"As stated in the previous post the material is Nitrile again as stated expensive at £2500 for a refurbished seal" ??????
A brand new XRV163 shaft seal kit, list price from Howden is less than half of £2500.
There has been one significant change in the Howden seals over the last few years, rather than fit the standard Crane units (Carbon - Carbon) we have now developed a more robust SiCarb - Carbon seal, at the same cost.
With the shaft seal being the one true consumable part of the compressor every manufacturer is looking at improvements.
Early XRV problems were bearing related, but were fixed almost ten years ago, all clear now.
Please feel free to post details where a seal a reasonable money can be bought and howden support can be had
Hi Quality:)Quote:
Originally Posted by Quality
long time no speak:D
Sealtec for refirbished seals. (I will take a look in the morning for details).
Not sure who to contact about support. I would tend to go to the package builder and let them sort out with Howden.
Kind Regards Andy
We still have not heard back from Canadian Ice. Perhaps the network has frozen and not connecting.
magoo
Good work Boys,
Have a couple of MK255's a the ammonia import terminal that were doing the same thing.. casing seals too thin & inner seal rings on both were almost petrified.. Went Nitrile @ SKF..
Passed on the savings too...;)
I have had very good experience with CAMCO 717-SC compressor oil it has a very good seal conditioner. Just Goggle CAMCO Lubricants for info.
You may want to check end play in the input shaft. Is it a 127 or a 204? Since the compressor has a gear case the input thrust bearing may have enough play to allow the shaft to be moved back by internal pressure enough to allow the oil on the mating surfaces to dry out and allow gas to escape. Also the shaft moving back reduces the load on the mating surfaces and can cause it to leak after being shut down for a few hours.Quote:
Originally Posted by Canadian Ice
I had a Howden once, the seals would not seat when shut down. oil, o-ring type, and alignment are not the issue since these affect the seal when running We found the issue to be the hard face from the factory was not totally flush. It was .01 higher on one side. When not running, it would start leaking.