PDA

View Full Version : Grasso 69, Discharge Temp to High







Jomoniak
02-05-2008, 06:54 PM
Hello! I,am from Sweden and new member in this forum. Problem with slowly rising discharge temp to 140 degrees and compressor stops. Normally temp 117 is notised on the second copressor (idetical to this one. It begans after a 30000 hour service(32000). Disharge valves/spring has renew and the valve lifting control mechanism(capacityregulation) piston oring renew. Oil and suction/disharge filter is changed. No problems with overheat before the service! I have controlled that the magneticvalves to the valve lifting control mechanism is working. Put a manual oilpump to the oil pipe supporting the valve lifting mec. and visually see the movement is correct. When the compressor runs i cant say if the stages puts in correctly. Can oilpump give bad pressure, and now when new tight orings is mounted in valve lifters it just cant manages to fully step in the stages? Going back on monday to put a oilpressuremeter to oil pipe supporting the valve lifting mec. The oilpressure to compressorlubrication is 4.9 Bar(adjustable but not effect the valve lifters. Maybe someone have a clue wat is wrong with this Grasso 69 Sorry for my bad English.

Grizzly
02-05-2008, 07:05 PM
Without doubt it is highly likely 1 or more of the Discharge Valve rings are misaligned within the cage assy.
Or a valve seat is damaged.
Given what you have described you need to checkout the Discharge Valve Assemblies.
If you need a manual Let me know?
Cheers Grizzly

Jomoniak
02-05-2008, 07:16 PM
Without doubt it is highly likely 1 or more of the Discharge Valve rings are misaligned within the cage assy.
Or a valve seat is damaged.
Given what you have described you need to checkout the Discharge Valve Assemblies.
If you need a manual Let me know?
Cheers Grizzly
Thanks Grissly! I will checkout the Disharge valves.

RANGER1
03-05-2008, 06:30 AM
Also make sure you artificially load cylinders before installing discharge valve assembly and bolt down head.Otherwise loading gear could be damaged/jammed plus assembly may not seat on top of cylinder liner seat

Grizzly
03-05-2008, 10:27 AM
Also make sure you artificially load cylinders before installing discharge valve assembly and bolt down head.Otherwise loading gear could be damaged/jammed plus assembly may not seat on top of cylinder liner seat

Hi Ranger.
Are you sure you have the correct Compressor.
Respectfully I have never had to do that on a GRASSO RC 9.
I don't think it's standard practise maybe some of the Grasso Guys can help here?

Jomoniak.
A couple of other points, I assume the comp is air cooled?
Also another thing that can cause the problem is a passing By Pass Safety Valve.

SORRY JOMONIAK. I have just re- read your thread. I think I have mislead you.

Basically if the heads are not loading up properly you will experience high head temperature.
There are also other issues which I will talk to you about later but before Monday. (She who must be obeyed wants to go out. Inconvenient I know!)
Cheers Grizzly

RANGER1
03-05-2008, 11:37 AM
Grizzly,
No , but have heard this happening on a 2 cyl grasso.This important procedure was missing in manual where you have to pump oil or air into unload piston before assy of discharge valve assy + head.If unload pins are not down nothing will seat + maybe damage mechanism.Like sabroe,vilter,mycom,etc

RANGER1
03-05-2008, 11:42 AM
There might be something special with oil circuit as well,like 2 differant pressures.1 pressure for unloaders and another for crank ?

Jomoniak
03-05-2008, 11:59 AM
Hi Grizzly! comp is air cooled and i Disassembly and change the white disc and the lenght of spring was ok in the Pass Safety Valve. I have to shut down the nerbye 2 Compressors for hawing a chance to hear if some of the 6 cyl. not been loaded when Monitron and selenoids says 100%
Thank all of you Guys for tips and interest!

Jomoniak
03-05-2008, 12:32 PM
There might be something special with oil circuit as well,like 2 differant pressures.1 pressure for unloaders and another for crank ?
Hi RANGER1! I thought it have to be a unadjustable pressure direkt from oilpumphouse beacause there is no oilregulator out from the house to pipe supporting the unloaders. Earlier service on Grasso 12E have 2 regulators located on right and left side on the pump whith a larger pressure on the unload/loaders. Bye the way i have reread the manual from Grasso and there is described to force down the pins before put the valve assy in place, havent done that maybe i have get some in bad position? Just before this service the sister compressor have its 30000 hour by me with no problems like them on this (i used the same reassembling on that, maybe just lucky?

Grizzly
04-05-2008, 02:11 PM
Grizzly,
No , but have heard this happening on a 2 cyl grasso.This important procedure was missing in manual where you have to pump oil or air into unload piston before assy of discharge valve assy + head.If unload pins are not down nothing will seat + maybe damage mechanism.Like sabroe,vilter,mycom,etc

Basically the Grasso system of unloading does not require any form of mechanincal "setting" Prior to rebuild.
If only the suction & discharge valves and assemblies are being inspected,
If the liners are moved however (and this is where your referance comes in Ranger ) the unloading gear has to be removed and replaced once the liner has been repositioned!

Jumoniak

I Have attached the faults page for an RC9.
When you refer to comp lubricating pressure where are you measuring this pressure from?

If it is from the system compound gauge this is oil differential. (the differance between the suction pressure and the oil press)
This pressure should be 1.5 bar (approx 21 psi) anymore and the surplus pressure will just compound seal and bearing wear.

To measure the oil pump pressure (13 -15bar above suction). You can attache a STEEL BORDON TUBE GAUGE (the ammonia eats the copper ones) to the tee piece below the oil pump.

Make sure that the gauge is at least 25 bar range.
Because despite assurances to the contary I have seen this sort of surge pressure at the oil pump upon start up.

Incidently within the oil pump there is a hydrolic delay valve which delays cylinder loading by 30 - 60 sec.
If this has stuck the heads will not load. these can be affected by all sorts of foreign matter.

Good luck and let us all know how you get on?
Cheers Grizzly

Jomoniak
04-05-2008, 08:20 PM
Hi Grizzly! I get the pressure from the system compound gauge and Monitron. Better turn pressure down then. Got a gauge to check pump pressure tomorrow. Thanks

RANGER1
05-05-2008, 02:21 AM
Grizzly , not having worked on one first hand i have described other machines .Grasso describe assy of valve gear on page 4.29 4.31 of RC9 manual .
It describes having control piston of the valve lifting gear removed and you push lifting pins down before installing valve gear. After assy of valves + head , reassemble control piston assy.

Grizzly
05-05-2008, 09:42 AM
Grizzly , not having worked on one first hand i have described other machines .Grasso describe assy of valve gear on page 4.29 4.31 of RC9 manual .
It describes having control piston of the valve lifting gear removed and you push lifting pins down before installing valve gear. After assy of valves + head , reassemble control piston assy.

Humble Apologies Ranger.
You are correct in what you say.
I was reading from the wrong manual.
You do indeed have to remove the valve lifting assy.
Prior to reassembly of the suction and discharge valves and cages.
Whereas this is not necessary on the larger models!!!
Hence my assumption.. They say you are never to old to learn!
Thanks Grizzlyhttp://www.refrigeration-engineer.com/forums/images/icons/icon11.gif

Jomoniak
05-05-2008, 07:18 PM
Hi! Home again after a day with the Hot Graasso. Problem is solved!!! Oil pressure was OK, Dishargevalve assy was OK in line. When it come to reassembling all again i use a hand driven oilfillpump connect to supportpipe for cap.reg.to press down the lifting pins. Put the suction valve rings back in the deeper seat now. Start up and all is normal as before service! 120 degrees (-12/+34) Must have been one or more suction valve ring that not was in position?. Feels good now, tough when we got heat in Sweden now and the plant needs this 3 compressor. Many thanks to all of you, maybe i can help somebody in this good forum.

akbar
05-07-2008, 07:58 AM
hi grasso 69.I needed information in case of sizing in ammonia system.can you help me?