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pump pressure pulsating

Discussion in 'Pesticide & Herbicide Application' started by turfmanagementspecialty, Oct 9, 2010.

  1. turfmanagementspecialty

    turfmanagementspecialty LawnSite Member
    Messages: 96

    I just replaced the diaphragms in my Hypro D403 pump and went out to spray today and the pressure was pulsating a bit. Pressure would go up to 160 then drop to just over 100. What could possibly be the issue? Thanks
  2. jbturf

    jbturf LawnSite Bronze Member
    Messages: 1,472

    i recently had a pulsing issue on my 403, up down up down
    pretty fast though, it would make the hose jerk around

    turned out to be a tiny piece of crud keeping one of the
    valves stuck open

    luckily for me it was only the 2nd valve i checked till
    i found the culprit, (there are 6 of them)

  3. ToniDavies

    ToniDavies Sponsor
    Messages: 140

    Sounds like you do not have enough air pressure in the head of the pump. You want to add about 40 psi air pressure start up the system is the gauge is bouncing all over the place (pulsing) slowing let some air out until it is steady.
  4. jbturf

    jbturf LawnSite Bronze Member
    Messages: 1,472

    how do you add air to the d403?
  5. ToniDavies

    ToniDavies Sponsor
    Messages: 140

    Sorry JBTurf the D403 does not have an air valve. I am so used to the question with the D252, D30 etc and forgot this model Hypro pump does not have an air valve.
  6. Ric

    Ric LawnSite Fanatic
    Messages: 11,969

    Air is more compressable than water. Adding a Water Hammer damper is fairly simple but only masks a problem on certain style pumps. They are nothing more than a Tee on the pressure line side that goes to a dead end air chamber. They are installed so gravity keeps the solution out by compressing the air which is higher. On pressure washers they use a special hose that expands as a pulse damper
  7. Pumptecguy

    Pumptecguy Inactive
    Messages: 71

    The pulsation from the pump can come from a few places. Air leaks on the inlet side, a crack on the pump body, an old regulator valve that leaks internally and has become hydraulically unstable, etc....

    You are correct that air will compress and water really will not. Accumulators (dampeners) are specially designed and precharged/loaded based upon the system pressure and displacement. A simple Tee with a vessel of air above only works in cartoons or your imagination. The water will force the air into solution even at very low pressure and remove any imagined dampening. Many, many people have been harmed by this misunderstanding when their galvanized plumbing vessel exploded on their high pressure washer. They usually do not live to tell. It is not a joke.

    Pulse (dampening) hose is specially wound to absorb energy (pulse). There is only 1 quality manufacturer and the rest is junk. It was originally developed by an engineer at Chrysler to eliminate the chirping sound in early power steering systems. Pumptec is largest customer of pulse hose in the country and one of the founders refined it for pressure washer use 35 years ago.
  8. Ric

    Ric LawnSite Fanatic
    Messages: 11,969

    Pump Guy

    Sorry BUT, Tell that to my Beam Pump and my galvanized Air Chamber that has been working for well over 10 years. The trick is to have a long small diameter pipe leading to a large diameter pipe as a chamber. The Higher the Chamber above the tee the better. When the pump is off you must relief pressure from the hose or out let side.
  9. Pumptecguy

    Pumptecguy Inactive
    Messages: 71

    No need to apologize. Maybe you need a visual example:
    Take a clear bowl line strainer and attach it above any diameter pipe you pick, then start to pressurize. If your eyes are open, then you will see all the air evacuated and that clear bowl filled with water. Can you imagine anything magical about your galvanized version of this? All you have created is a small water tower that wil hold a volume of water, but it does not dampen.

    This misconception is very dangerous. Your Bean is probably at a low enough pressure, but there are others that will use this at higher pressure with lower strength materials and get hurt.

    There are old, cast iron accumulators that look like these ad hoc plumbing creations you reference, but these are made correctly with diaphragms and some type of precharge or load. Shade tree mechanics saw these devices and said, 'Ah, shoot....I can just make one of these. It's just plumbing fittings'.

    Take it off and test your pump. It will preform the same, unless you want to imagine a change. Who knows, you may even look inside and see that long ago it used to have a bladder or ball inside to absorb energy.
  10. Ric

    Ric LawnSite Fanatic
    Messages: 11,969


    Once again It has BEEN WORKING for over 10 years on my Beam pump and longer on other beam pumps since that was the way the factory installed them.

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