Help!! leaky pressure switch

  1. mjrally Member

    Messages:
    88
    uk
    Right then guys before i go out and buy a new one, can anyone tell me if they see any issue with me replacing my pressure switch (which just started leaking this afternoon mid spraying my car:( ) with another, off spare compressor i was going to build up. The diffefence between the two is that the second one is from a three phase compressor and so is specified for 400V. When i got the unit it came wired with conventional blue brown green/yellow so i dont think wiring should be an issue.

    So basically can you see any issue with me using it? as surely it will just be the contacts that are rated for a circuit amperage and 400V??

    or is there other gubins that im not aware of?

    Any help much appreciated!!
     
  2. rtbcomp

    rtbcomp Moderator Staff Member

    Messages:
    18,615
    Location:
    Sheffield UK
    You should be OK, just use two of the contacts, one for live & one for neutral.

    Before you change it, check to see exactly where the air is coming out. If it's from the unloading valve (close to the thin pipe) with the motor switched off you may have a faulty non-return valve.
     
  3. mjrally Member

    Messages:
    88
    uk
    Thanks for the quick reply! The leak appears to be only when the motor kicks in, but then it leaks enough to not be able to build the pressure back up again to cut off. It feels as though it coming from the small hole where the needle allows the pressure through when switching off. But pull the plug out and it holds pressure.

    Ill have a go in the morning and see where i get!
     
  4. rtbcomp

    rtbcomp Moderator Staff Member

    Messages:
    18,615
    Location:
    Sheffield UK
    Pull the plug whilst its running and then immediately switch off using the knob on the pressure switch. You should get a brief hiss. If it keeps on hissing then the NRV is duff.

    If it holds pressure the diaphram in the switch will be OK.

    The unload valve may be faulty, sealing after the pressure has dropped.
     
  5. mjrally Member

    Messages:
    88
    uk
    Right then, swapped the pressure switch today, same issue with the new one, so i assume it must be the NRV. So plan B, i whipped the NRV off, stripped it and noticed that the rubber plunger had a fair indentation in so i trying a gentle rub down to flat it off and popped a washer in there to increase the spring pressure. This plan basically back fired and my attempt to flatten it made it just leak!........So plan C. I then swapped the NRV with the one of the other compressor (the fittings were not the same so after changing pritty much all the pipe work). This then leaked exactly the same and as i adjusted the screw on the pressure switch for it to trip at the correct pressure, the pump starting making a "pinking" noise when getting to high pressure?

    Really confused now? any ideas why i still have a leak and why the pump seems to now struggle. At first i though i may have piped it up wrong but it is exactly the same way it was before and has run for years without issue? Are the non return valves rated?
     
  6. rtbcomp

    rtbcomp Moderator Staff Member

    Messages:
    18,615
    Location:
    Sheffield UK
    Any chance of some pics? Just in case it isn't the standard setup I'm assuming it is.
     
  7. mjrally Member

    Messages:
    88
    uk
    Here's a few, ignore the fact there is two manual pressure release valves as i had to use an extra one as a blanking peice.
     
    • 110B1113.JPG
    • 110B1114.JPG
    • 110B1115.JPG
  8. mjrally Member

    Messages:
    88
    uk
    one more
     
    • 110B1116.JPG
  9. rtbcomp

    rtbcomp Moderator Staff Member

    Messages:
    18,615
    Location:
    Sheffield UK
    That looks conventional enough.

    The pump has to overcome the pressure in the tank plus the force exerted by the spring in the NRV so strengthening the spring may be overloading the pump?? Seems unlikely though as the NRV springs aren't all that strong. Unless someone's put a stronger spring at some point in the past?

    This is an NRV which I dismantled earlier!

    [​IMG]
     
Advertisements