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usgreg
07-06-2014, 12:46 PM
Has anyone had issues with discharge valve failure on vilter recip's? I am not onsite to monitor operation, so it is hard to see all conditions. No sign of high oil temp or liquid coming back from recirculator. This occurs on the same valve once every 6-8 months. Checked suction strainer and is clean. looking from the top with discharge on the left and suction on the right, it is the bottom right cylinder. good oil pressure and The discharge temp is within ten degrees of the other booster next to this one. Using a infrared gun, the head temp is no different than the other heads when fully loaded. When all heads are removed, their is equal oil film on all components, so oil supply appears uniform. Thanks in advance for any suggestions.

RANGER1
07-06-2014, 01:50 PM
Has anyone had issues with discharge valve failure on vilter recip's? I am not onsite to monitor operation, so it is hard to see all conditions. No sign of high oil temp or liquid coming back from recirculator. This occurs on the same valve once every 6-8 months. Checked suction strainer and is clean. looking from the top with discharge on the left and suction on the right, it is the bottom right cylinder. good oil pressure and The discharge temp is within ten degrees of the other booster next to this one. Using a infrared gun, the head temp is no different than the other heads when fully loaded. When all heads are removed, their is equal oil film on all components, so oil supply appears uniform. Thanks in advance for any suggestions.

Usgreg,
Does the 450 have valve plate?
I think it does as opposed to the 440 having a diaphragm.
Can only think of poor valve seat condition on discharge valve seat or cylinder top liner seat.
Maybe you could check with valve leak back test to eliminate valve seats in poor condition or "0" ring on cylinder liner damaged.
Also unloader's operation, do unloader's pins definitely clear suction valve to seat.
I realise temps are ok, but only offering some basic checks if no floddbacks etc.
Also are you using genuine Vilter parts?
Clean water jackets with good water flow?
What is the running discharge temperature?

Grizzly
08-06-2014, 12:23 AM
Hi usgreg.
Ranger is on the ball.
I have seen/ had return visits with a recip that had a particular cylinder valve plate failing.
I don't know vilter but assume it is similar to many?
The issue I discovered was down to a "spider" (Valve cage) which was not sitting down on the discharge plate evenly.
You could only just make out the tiny rock across the cage, when looking for it with a thoroughly cleaned assembly and a nice clean surface plate. In fact I had to use a new assembly as a template to prove the issue.

It's just possible you have a similar issue?
Likewise a badly damaged crown of the piston caused by previous valve plate damage.
Unless cleaned properly to maintain the bump clearance can case similar failures.
Grizzly

RANGER1
08-06-2014, 01:13 AM
Usgreg,
In a nut shell prove all valve seats, suction,discharge & top if liner are sealing & no wire drawing on any of the seats.
Sometimes if you have a broken valve it can also damage valve seat.

As Grizzly mentions check bumper clearance on at least this cylinder & unloader pins are below suction valve seat when pushed in.

usgreg
10-06-2014, 03:04 PM
Thanks for some good info. I have not been back onsite yet. the head and oil cooling is ammonia, and is clean. Yes, valves are plates. unloader does allow suction valve to seat properly. I have replaced the valve plate, valve springs and cage, not the liner, so discharge seat is new. Top of the piston is not smooth anymore from previous failures, though I have smoothed it down with sandcloth and scotchbrite pads. I have not performed a seat leakdown test. genuine vilter parts and discharge temps around 180 F.

RANGER1
11-06-2014, 10:32 AM
Usgreg,
Does this machine cycle off much?
Might be hard to prove, but consider non return valve after oil separator in discharge line.
if any liquid condenses in head/s, maybe for whatever reason this piston cops it.
Especially if valve seatsare not perfect.
IF it does cycle off for awhile it would be ideal to see it restart, listen etc for anything unusual.
Also you mention liquid cooled heads, is that high pressure liquid ammonia in jackets instead of the usual water jackets I have worked with?

usgreg
11-06-2014, 03:39 PM
These compressors (2 high stage, 2 booster ) each have a "viltech" controller, so pressure, temperature and cycle timing are more accurately controlled, (no system PLC) and yes this does cycle off as I do not like to let them run for extended periods of time fully unloaded. Unloaded head temperature appears to build up in this mode. I have used a stethoscope on start up on each head and do not here anything unusual. It does not stay off for more than 2-4 minutes and has a drive for a soft start. controls for speed control have not been installed. Vilter has stated that they can go to as low as 50% speed (fully loaded) and maintain adequate oil pressure. Liquid trapping is possible, but I did not think it could happen in the 2-4 minutes of off time. The ammonia liquid for head/oil cooling is from the high temp recirculator and regulated down to feed each compressor. When you refer to a non-return valve, is that the same as a check valve? There is a high level safety on the recirculator as well.

RANGER1
11-06-2014, 09:16 PM
These compressors (2 high stage, 2 booster ) each have a "viltech" controller, so pressure, temperature and cycle timing are more accurately controlled, (no system PLC) and yes this does cycle off as I do not like to let them run for extended periods of time fully unloaded. Unloaded head temperature appears to build up in this mode. I have used a stethoscope on start up on each head and do not here anything unusual. It does not stay off for more than 2-4 minutes and has a drive for a soft start. controls for speed control have not been installed. Vilter has stated that they can go to as low as 50% speed (fully loaded) and maintain adequate oil pressure. Liquid trapping is possible, but I did not think it could happen in the 2-4 minutes of off time. The ammonia liquid for head/oil cooling is from the high temp recirculator and regulated down to feed each compressor. When you refer to a non-return valve, is that the same as a check valve? There is a high level safety on the recirculator as well.

usgreg, yes check valve, but appears as you say not the problem, just trying to work through the possibilities.

The high level, does it work or tested recently, time delay?

Is there anytime level could be higher than normal in recirculator?

Does Vilter have any ideas, not sure do they have a help line to help narrow thing down.

Usually broken valve is liquid slugging, overheating or metal fatigue!
It's a pretty simple compressor so frustrating.

Maybe concentrate on that cylinder to eliminate damaged liner seat etc.
Oil pressure OK 45-50psi.
If you test unloaders while running, do amps change same on each cylinder bank?

usgreg
16-06-2014, 05:38 PM
High level safety has been checked, and yes, is working (shuts compressors down). No time delays. Maintainance staff checks levels (hanson electronic level controller with digital display) daily and has not seen any fluctuations. there is an alarm on this controller as well, and has not been triggered that I am aware of. Oil pressure is very good (50-55 psig) with no alarms or cutouts. the other booster has a slightly smaller motor than this one, but they both have fairly equal amperage differences through the unloading. Vilter is the source that originally informed me of slugging or dirt in the suction strainer. I may order a new piston and liner as a preventive measure. I don't like changing parts if I'm not sure of issue. I am thankful for this group for all your help.

RANGER1
16-06-2014, 08:57 PM
Usgreg, NH3LVR might be worhth contacting, he has a lot of Vilter experience.