Howden slide valve problems

[CanadianIce]

Hi Guys
I ran into a problem that I haven't encountered before, while overhauling a Howden WRV 204/165. Enerything was going well until I installed the slide valve. The farther it was pushed into the load position, from 50% to 100% the more resistence was felt until it finally stuck,I had to temporarily install the piston so I could draw it back out. From 50% to 0% it moves with a slight resistence. Installed the guide bracket thinking that this would complete the alignment even though I never had to do this before; however, this did not cure the problem. I loosened off the injection tube cover and the slide valve released and moved smoothly.Tightened the injection tube again and the slide valve bound up again. Removed the injection tube completely and inspected. It appears the last time this machine was overhauled, the tube may have been damaged and was built up then machined down to original diameter. Removed the slide valve and inspected, no signs of wear or misalignment. Checked the new PTFE seal that runs over the injection tube. Nothing unusual there. Slid the tube into the slide valve on the bench and it appeared to move smoothly but if I move the tube slightly out of alignment, it would bind as expected. I believe the injection tube is slightly bent due to the earlier machine work. The customer complained that this compressor would load but wouldn't unload all the time. I didn't get the opportunity to test the slide valve when the compressor was being dismantled. Any suggestions, thoughts or similar experiences?

Thanks
C Ice

[Grizzly]

Hi C Ice.
It sounds as if you have got it covered.
Definitely sounds as if there is an alignment issue.
Let us know how you get on.
cheers
Grizzly

[RANGER1]

Have had this problem on 1 machine same size , also had been re-hardchromed etc .

When you push oil injection tube in and 4 bolt flange touches its flange face , check for gap under flange faces with feeler gauge .
Area where gap is ( if there is a gap ) can be shimmed in that spot only to correct alignment of tube .
This flange face is sealed by an "0" ring so shim only around edge of flange so not to disturb sealing of "0" ring .
The one I did had a .005" part shim , then all ok .

Alternatively get a machine shop to check/correct flange on end of oil injection tube so it is at right angle with tube .
It does'nt have to be out much .

[CanadianIce]

Hi guys

Ranger1, that was a great tip. Had it shimmed up in no time and now it's ready to go back on the base. I appreciate the help.

C Ice

[RANGER1]

Canadianice

Happy to help .

Have just worked with a couple of Canadians on a natural gas field site .

They work for Enerflex , Alberta .

[THommy]

Hello C ice,

Pull the guide pins out of the mounting flange.
Then fasten the bolts slightly, and move the slidevalve upwards and downwards. Then fasten the bolts tight.
Normaly this must reach.

Best regards,
Jeroen

[CanadianIce]

Hi THommy

That was one of the methods I tried originally but the adjustment needed was angular rather than offset so when the flange was tightened, the tube would bind again. Compressor is back on the base and running well.

C Ice

[tabreed717]

You guys are great, thanks for the valuable discussion, I wish if I can help but this type is new to me.

[magobha]

Hi Guyz l'm currently working on a howden also and it was running all along but now its suddenly jammed at 50% and won't offload, tried to turn the slide manually but it won't move any ideas?

[vskrishna6]

Hi, I am working on a HOWDEN XRV 127 R35 oil injected screw compressor. There is a problem with the capacity control. The compressor loads fully immediately on starting. Can someone let me know where to look for a service manual on-line ? Thank you.