nuvair compressor issues

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Messages
4
Reaction score
0
Location
Manteo, NC
# of dives
5000 - ∞
I am having problems with a Nuvair mch-16 and would like to get some input from other owners of same compressor. I bought this compressor new in 2010 and have had to figure it out ever since. I've been all through it at times and it has continued to work. We have a pretty busy shop so it runs a lot in the season. It has now developed a kinda "hiccup" if you will. Purely random. I have done all maintenance on it as called for. Valves changed, oil fresh, drive belt, replaced high pressure cooling tubes were replaced after developing pinhole leak. I thought the current problem was the result of purge issues. I have cleaned the condensate separator and the purge manifold before and thought that might be the problem. Overall, everything was good though. Found O-ring in manifold block where h.p. Hose from bottom of filter tower connects to be bad. Replaced it. I have cleaned all the air lines/tubes, new valves on all three stages, checked amperage on both legs and that is stable, run capacitor is good, (I've had to replace both start and run capacitors before), the "hiccup" is very fast and random as I said, but when it occurs the 1st stage meter will have a slight pressure increase and at the same time the 2nd stage valve will have a slight decrease. It may only happen once, or it may be several times in succession. The I have also opened the manual purge valves to allow more condensate out in between purge cycles, but that does not make a difference. Other than this, the machine works fine and will pump up to pressure (I only go to 4000 psi for my banks). I'm just really concerned about some type of catastrophic failure. It has 1650 hrs, so I would not expect crank/rod bearings but I don't know. Checked piston rings in 2nd stage also, seem fine and 3rd stage seems to have no issues. Any info will be greatly appreciated. Capt. Matt Landrum
 
would appear to be a bad valve between the 1st and 2nd stage
That's what I thought as well, so I replaced both 1st and 2nd stage valves. In fact I had 2 sets of new 2nd stage so I changed them twice on the thought that maybe 1 of the new sets were bad. I find it unlikely to get 2 new sets that are both bad. I also installed new 3rd stage.
 
not familiar with that compressor, but if you have high 1st stage pressure and low 2nd stage pressure, it means air is going backwards. May be an installation torque issue or the face of the valve seats not being perfectly clean
 
not familiar with that compressor, but if you have high 1st stage pressure and low 2nd stage pressure, it means air is going backwards. May be an installation torque issue or the face of the valve seats not being perfectly clean
If the OP changed valves twice, I'd be looking at the valve seating surface in the head with a magnifying glass. Doesn't take much of a crack/ding to really mess up your pressures. I'd be checking that second stage suction valve the closest.

What concerns me is that it only happens part time. Were the valves carboned up badly? Could a chunk of dreck be floating around in there, getting stuck in the valves, and then going floating off?
 
It could be that the valve plate needs to be replaced. A few years ago, the valves had a copper gasket and torquing set it pretty well. They changed to an o-ring on the face and some of the valve plates had oval holes and the o-rings sometimes wouldn't seal. Of course, that doesn't explain what is happening with you since yours only happens once and a while. I have a couple of refurbished valve heads if you are interested.

And if you want to call Nuvair, I would ask for Mitch. If he can't answer your questions, he will find the right person.
 
It could be that the valve plate needs to be replaced. A few years ago, the valves had a copper gasket and torquing set it pretty well. They changed to an o-ring on the face and some of the valve plates had oval holes and the o-rings sometimes wouldn't seal. Of course, that doesn't explain what is happening with you since yours only happens once and a while. I have a couple of refurbished valve heads if you are interested.

And if you want to call Nuvair, I would ask for Mitch. If he can't answer your questions, he will find the right person.
Thanks for all the input. I did replace the entire head, I guess called valve plate. All was new . Same with 3rd stage, 1st stage is a single plate under the head. I did torque specs according to manual. I've tried the nuvair route before and I will remain politically correct and not address that sentence.
 
I will add that I am having to continue to fill tanks, air banks and nitrox fills. I filled 40 tanks plus my banks a few days ago which was about 6 hrs and today filled a dozen tanks and banks about 2 1/2 hrs and compressor will run great, just really concerns me. I have to baby sit the entire time, I won't walk away from it, worried about some catastrophic failure. When I fill nitrox banks I won't leave anyway but having to be there constantly for air is a lot of time. I keep coming back to maybe it's a purge issue with the condensate separator, it's almost like it's getting "hydrostatic lock" for a micro- second in the 2nd stage. But even pushing the manual purge and opening the valves does not stop it. I am in an area of high humidity and I'm thinking to change the purge times and duration to see if that makes a difference, also maybe switch to a tropical configuration with an additional water separator
 
Thanks for all the input. I did replace the entire head, I guess called valve plate. All was new . Same with 3rd stage, 1st stage is a single plate under the head. I did torque specs according to manual. I've tried the nuvair route before and I will remain politically correct and not address that sentence.

:D I think I know exactly who you talked to. They have some GREAT mechanics that are terrible on the phone. Again ... if you call them, ask for Mitch.
 

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