it broke [Davey Compressor]

[cowboy]

something bad happend to my compresser yesterday anybody got a book on the 4 cyl raidal davey 15 cfm it has a bunch of automatic crap on it witch is nice when it works but it is stuck in the unloaded cycle and just blowing gas up the stack it is nice not having to blow down the traps and all but I am thinking I may have to strip all of it off and just build some manual drips to catch condensate at each stage anybody work on these things in the service? thanx

[cnghal]

Re: it broke

Bad blowdown valve?
I've had a few Dragon Valves lately from the mid 90s that needed a rebuilding with a seal/soft goods kit because they were leaking badly and over pressurizing the blowdown tank.
They also need Viton seals for NG that air compressors don't need/have.

[cowboy]

Re: it broke

ok I have been studying good thought hal have found a line that is got gas pressure on it and it is a pilot unhook it and the purge valve closes so I am trying to figger what trips it. always remember it is broke so you cant break it take it apart and figger out how it works than figger why it dont than cerect the problem all done dont I wish this thing takes a lot of figgering 2000000 hoses and air relays lines and traps but I will get it I am still looking for a book or someone who worked on them in the service thanx

[ccgas]

Re: it broke

sent you manuals on your e-mail address hope it helps. There a company that rebuilds the davey for the us gov next to the redstone arsenal in alabama. will look for the phone # and let you know if you still need some help.

[karl]

Re: it broke

something bad happend to my compresser yesterday anybody got a book on the 4 cyl raidal davey 15 cfm it has a bunch of automatic crap on it witch is nice when it works but it is stuck in the unloaded cycle and just blowing gas up the stack it is nice not having to blow down the traps and all but I am thinking I may have to strip all of it off and just build some manual drips to catch condensate at each stage anybody work on these things in the service? thanx

Hi Cowboy,
I have been tinkering with my davey trying to resolve a few lingering issues so I can contemplate putting it into service.

You might recall it only had 10 hours on it when I bought it but it is apparent that it suffered some oxidation in the valves sitting unused in all those years. I figured this was the cause of low pressure on the #3 stage pressure gauge but after disassembling the valves on #2 and #3 and cleaning up the valve discs and seats on some 600 grit wet sandpaper on a piece of granite it is still has low pressure on the third stage.

I get 52 to 56 psi on stage #1. 180 psi on stage #2. 400 to 750 psi on stage #3. Despite the low numbers on stage #3 it will still pump the receiver up to 3500 psi. I just don't know how efficiently it is doing so.


I am hoping for 850 psi on stage #3 per the manual.

A few observations is that the pressure on stage #3 seems like it only reaches more than 400 psi is when the receiver has more than 400 psi in it and then stage three pressure seems to go up with the stage #4 pressure but it never reaches factory manual specs of 850 psi.

Also when I shut down the compressor the second stage pressure goes up anywhere from 20 to 100 psi??? At first I thought it was the valves allowing pressure from #3 backflow into #2. Now I am thinking it is the continuous drain on #3 backflowing into #2.

I have taken apart the #3 head and cleaned and reassembled the valves in it 4 times and don't see much benefit in doing it again.

Next chance I get I plan on disassembling the continuous drain on stage #3 and double checking it as I have only checked it out once. I didn't realize there was an additional plunger/metering rod in behind the little stainless steel needle with and orifice in it until I found a technical drawing of it in the manual. I am hoping that additional metering rod is stuck and bleeding too much pressure from #3 back to #2.

I would welcome any thoughts you have on maintaining the valves and continuous drain assemblies.

I would also like to get a benchmark on how its volume compares to optimal. Do you have a rule of thumb for how fast it should fill the receiver from 0 to 3500 psi running at full rpm?

Thanks,
Karl

[cowboy]

Re: it broke

sounds like your compressor is doing fine just the outside parts might be causing problems 750 is fine for the 3d stage as far as filling the receiver I have never timed one but you can see the gauge move so not long a few min at the most 3-5? I will time one in the next week or so as far as the constant bleed that may be the problem but I would not get upset over it as long as it don't knock the popit valve off the seat on shut down. what have you done with the gas for the popit valves make sure you get it out of the box

[karl]

Re: it broke

So far I am only pumping air through the compressor and haven't thought about the popit valves. As I recall they have 1/4 or 3/8" pipe thread so I could see using some swagelok ips to tube adapters and routing stainless tubing to a common vertical stack outside the box. You already talked me through extending the exhaust and relocating the unloader vent tubes to that extension in a phone conversation.

How often do you find you have to service the valves on your Davey's?

Thanks for the input,
Karl

[karl]

Re: it broke

Hi Cowboy,
I checked the continuous drain from stage 3 to stage 2 this morning and everything looks fine. I get 400 psi easily on stage 3 but it won't go up to 750psi until I have over 2500psi in stage 4.

Running at maximum rpm it fills the receiver from 3000psi to 3500 psi in a minute. If I reduce the speed to 1000 rpm it takes 3 minutes to go from 3000 psi to 3500psi.

Running it at 1000 rpm I also get less pressure on stage 1. It was closer to 40 psi.

It looks like I should disassemble and clean the valves on stage 1 and stage 4 next.

Karl

[cowboy]

Re: it broke

if it is filling the receiver from 3000 to 3600 in one minute it is working just fine.dont worry.it has to have back pressure to run the stages up .checking valves never hurts though

[karl]

Re: it broke

Good to know. Thanks for the reply.
should I be using the mil spec turbine oil listed in the manual or is there a modern compressor oil that is a better alternative. The compressor only has 15 hours on it. My understanding is you can't switch to synthetics after running mineral oil for extended time so if I was going to switch to synthetic now would be the time.

Bauer seems to indicate you should specifically use mineral oil in their compressors if pumping cng so I am having a difficult time understanding the best oil at this point.

[cowboy]

Re: it broke

more important than what oil is that davey has a long start up of no oil pressure you might want to rig a prelube pump I am not going to tell you what you should run for oil but I will tell that I run 15-40 mobil one for high mile motors.But it is all on you to choose your oil as this is not in spec but can be bought at all wallmarts. my thoughts are that you should run mineral oil for the first 100 hrs than switch as I have had problems with both motors and compressors not seating in with using synthetic oils for break in