Engine driven air compressor episode 2

  1. Memmeddu

    Memmeddu Member

    Messages:
    2,947
    Location:
    Italia Sardegna
    So as expected I didn't manage to get one for free from a neighbor's friend .
    Anyway
    Free engine
    Free pump
    Free materials
    Now I'm trying to understand how to keep the project almost free.
    I should need a pilot valve which is enough expensive to stop the project.
    So I've already thought about modify a normal pressure switch to regulate the throttle by adding an extension to a leverage arm .
    Now my idea or better my question is , would be the air piston on the pressure switch enough strong to open a valve of an air gun?
    My idea is use it as a pressure discharge valve .
     
    Parm likes this.
  2. MCKDAVID Member

    might be possible to adapt something, but why take unecessary risks / complicate life?, unloaders aren't that expensive, from around 30 euros here. Compressors have the unloader and PSV for safety, the price would be insignificant if there was a problem. Remember even if you reduce the throttle to minimum, the pump is still producing significant quantity of air, which has to go somewhere, and cobbling together a airblow gun to vent it off is not a safe option I'd say..

    Understand the budget issue, but you've got all the expensive parts already, engine, pump and tank, the rest is peanuts relatively.

    As for engine control, you can get the proper part to control the throttle to drop to idle, a small piston / cylinder controlled by the air pressure, this is similar to the one I used on mine but you still need some form of overpressure relief for safe operation. These are less than 20 euros, again is it worth bothering with a DIY solution for that?
    https://www.ebay.co.uk/itm/Air-Comp...-Down-Control-Honda-GX160-GX200-/132306257478
     
    Memmeddu likes this.
  3. Memmeddu

    Memmeddu Member

    Messages:
    2,947
    Location:
    Italia Sardegna
    Almost 100 euros for the pilot/unloader valve and throttle control piston .
    I'll probably need to change the engine because I'm having issues with it
     
  4. Bill Edwards Member

    Messages:
    4,954
    Location:
    Scarborough, North Yorkshire
    You could just keep it nice and basic and have it blow off a safety valve when it gets too pressure. Valve dumps air, when the pressure drops again valve shuts. About £2/3 on eBay from memory, or rob an old compressor.
     
  5. Memmeddu

    Memmeddu Member

    Messages:
    2,947
    Location:
    Italia Sardegna
    I've thought that it could destroy the pump pretty fast .
     
  6. Bill Edwards Member

    Messages:
    4,954
    Location:
    Scarborough, North Yorkshire
    I've seen enough engine compressors set up like that to think it must be fine...
    At the end of the day, the pump should be designed/built to provide air at its rated pressure, what difference does it make if it's blown out through a valve or being taken by a windy gun, spray gun etc as in normal use?
     
    Memmeddu likes this.
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