Air Regulator Failure
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  1. #1
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    Default Air Regulator Failure

    Hi

    I have a NAPA 907770 regulator rated for 300psi, regulating range 10-250 psi. It is on a Quincy 7.5HP set at 175PSI.

    It has been working fine for about 5 years. I use it to regulator the line pressure, usually set at about 100PSI. When it ran today the regulator started making a lot of noise like when I change the pressure down. The needle fluctuates all over the place and air comes out of the relief hole near the top of the regulator constantly.

    I pulled the unit apart and looked at the diaphragm and could not find a tear or hole in it. If I set the regulator to a pressure lower than the tank pressure it does the above ie when it tries to regulate. If I set it to a pressure higher than the tank pressure it does not make any noise, which I would suspect as it is really not doing anything from a regulating point of view.

    Any advice , a replacement diaphragm from NAPA is going to be almost $40 and I am not sure that is the problem. I pulled the bottom off the regulator and it is just spring, oring, and the plunger that goes to the bottom of the diaphragm. Did not look like an issue.

    I know nothing about regulators so not sure what to try - any advice would be appreciated.

    Thanks

    Bob

  2. #2
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    Bob,

    The plunger must be free to slide in its bore. Clean it up, lube it 'lightly' and give it a try.

    Stuart

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    I have cut diaphragms. No big deal. I have two Devilbiss regulators that are the bell shaped design. Those diaphragms were a round sheet of copper. I found some shim stock of copper of the same thickness and cut out the new diaphragms. No issues.

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    Oftern can also be the valve faces not sealing, the best regulators are so called self relieving ones, on setting a lower pressure they vent the line down to this pressure, problem is as they age they tend to fleak on the regulation path and the vent path then vents hence they leak and make noise constantly when set to lower pressures, probaly could relap the valve faces, but its not really work it IMHO.

    IMHO best options just outright replacement, following the tips of one of my customers on site engineers, i too also now use and recommend the high quality Chinese knock off ones of the name brand styles, there quality is bloody good and the price points such you don't need to think about repairs down the road! Can't stress enough, the quality in them is on a par with the name brands yet less than a 1/4 the cost!

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  6. #5
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    We use the Parker 03/05/07 series of all metal regulators and I don't think we've ever had one fail in my 25 years of using them. Can't say the same for any other brand we've had (Festo, SMC, etc). That series of Parker regulators are just bulletproof.

  7. #6
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    After more playing around it is the seal on the plunger that is shot. I made a rubber washer that would lay on the top of the plunger. It stopped all the problems. I am not sure how long that washer just laying on top will work. I need to see if I can get a replacement plunger.

    Thanks for the pointers

    Bob

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    Tony

    I cannot find that series in the Parker catalog on line. Could you point me to a site that sells them or the Parker catalog page.

    Thanks

    Bob


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