Hypro d403

Discussion in 'Pesticide & Herbicide Application' started by nicelawns, Jun 1, 2008.

  1. nicelawns

    nicelawns LawnSite Member
    Messages: 29

    does anyone know how to regulate the pressure other than closing the return valve halfway?This is on a lesco space saver unit.
  2. philk17088

    philk17088 LawnSite Fanatic
    Messages: 17,386

    That is the only way I know of.
    I have a problem with water getting in the oil. I replaced the diaphragms and o rings and it is getting past somewhere. I tore it down three times last week.
    Are the diaphragms directional? It says "oil" on one side, I put that side down. The manual doesn't give any detail.
  3. nicelawns

    nicelawns LawnSite Member
    Messages: 29

    i don't have a leak...knock on plastic. I have to keep closing the return valve halfway around 200 psi to build pressure,I know this ain't how it works because it has a regulated,but it just doesent want to work.
  4. LawnTamer

    LawnTamer LawnSite Gold Member
    Messages: 3,986

    I have always had issues with my secondary bypass valve. I just use the return valve to regulate pressure and keep the red bypass valve closed. If I open it at all, I seem to get erratic pressure.
  5. Ric

    Ric LawnSite Fanatic
    Messages: 11,969


    Try installing this pressure relief valve just after the Ball valve. It can be adjusted to keep a constant pressure from the time you trigger you spray gun until.


    BTW be careful with the pipe threads on Hypro pumps, They are British standard threads instead of American. A Nylon Threaded coupler can be used and not leak or tear up the Steel British threads.
  6. RigglePLC

    RigglePLC LawnSite Fanatic
    Messages: 13,793

    I have a D232. There should be two knobs. One knob (red on my pump) releases all pressure back to the tank--or if closed clockwise--allows pressure to build up to the level set by the separate pressure regulator knob, which adjusts a steel spring which pushes against a valve seat. Hypro does not make a good pressure regulator valve. Mostly plastic--wear prone--does not tolerate grit or wettable powders.

    Ric is so right. Best to install a real pressure regulator valve,(sometimes called an unloader valve or pressure control unit), (about 7 dollars)--plus a ball valve to release the pressure back to the tank when no pressure is needed. However, I always use a Spraying Systems bronze pressure regulating valve with stainless steel valve seats; far superior and longer lasting. Sixty five dollars.

    And yes there is an inside and outside for the diaphragms. Try to put the retaining bolt in from both sides. One side will fit easily. On my pump--the writing and part number goes to the inside (oil side).

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