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Centrifugal pump concerns...

Discussion in 'Organic Lawn Care' started by lawncuttinfoo, Apr 10, 2008.

  1. lawncuttinfoo

    lawncuttinfoo LawnSite Bronze Member
    Messages: 1,010

    I stopped by a local sprayer company today and a few things he mentioned about centrifugal pumps and why they do not use them in many lawn applications.

    The reduced psi will have difficulty pumping 300 ft (the length of the hose) Also, centrifugal pumps can not be run dry like diaphragm pumps can. Meaning you better not run dry at the back of the house or your pump may be shot by the time you get back to it to turn it off.
    Lastly, not a huge deal but since you can not run them dry that means you can never use all the compost tea, resulting in a bit of unused tea every day.

    I have never heard these points discussed about Centrifugal pumps so I thought I would bring it up.
  2. ICT Bill

    ICT Bill LawnSite Platinum Member
    Messages: 4,115

    These don't, I have seen people run them for a day without fluid in them and they keep on working, just to see if they could. Roark

    Albeit they are for ponds in their marketing I'm sure they would do the same thing. They are known for their customer service so give them a call with comparable pumps and see if they fit the bill

  3. ToniDavies

    ToniDavies Sponsor
    Messages: 140

    Centrifugal pumps that are used on sprayers are designed to be used for exactly that purpose. Hypro and Ace pumps are the most popular. Pressure is not a problem to pump through 300' of hose as alot of people using diaphragm pumps are only running at 40 psi and get through the hose without a problem. These pumps feature ceramic mechanical seals which can be run dry for a couple minutes without a problem. We have sprayers out in the field with centrifugal pumps that have not been serviced for over 10 years.
  4. CrownLawnSvc

    CrownLawnSvc LawnSite Member
    Messages: 51

    I use a centrifigal pump sprayer. Pressure is not an issue. If you wanted to spray trees, then pressure would be a concern. Running it dry is a concern. The biggest problem is refilling with cold water on a hot ceramic seal.
  5. Tim Wilson

    Tim Wilson LawnSite Senior Member
    Messages: 795

    I have a question. When you folks are using the term centrifugal are you referring to impellers which spin or are these true centrifugal pumps which would imply they operate with no impellers.

    If this is the case what pressure/volume do these pumps operate at?

    Tim Wilson
  6. Tim Wilson

    Tim Wilson LawnSite Senior Member
    Messages: 795

    I am going to answer my own question here. After looking up the schematics of a few 'so called' centrifugal pumps I realize that they do operate with impellers. Although it appears that this is a gross miscarriage of the English language and the science of physics, it is a term used to describe pumps with impellers. True centrifugal force would not involve the use of fins or propellers. Your speed boat does not operate with centrifugal force.

    Anyway having said this, in addition to drawing your attention to my previous thread about biology surviving impellers, we use a pump with impellers to deliver compost tea at a distance of over 500 feet through 1.25 inch poly pipe. It has enough force after travelling this distance to operate 50 shrubhead sprinklers at once. The pump is 1.5 hp, rated at 50 to 75 PSI and high volume (can't remember). It is available through Princess Auto for under $400. It is built like a a tank.

  7. muddstopper

    muddstopper LawnSite Silver Member
    Messages: 2,341

    Centrifical pumps are usually more for high volume and low pressures. I wouldnt hesitate to use a centrifical pump to pump distance of 300ft and even more. The biggest problem with centrifical pumps is head height, the distance the pump can push water uphill. For most C-pumps this is limited to around 80ft of height. Pressure is also usually limited to around 80psi. Thats not to say for a few extra dollars you cant buy C-pumps that can push over 200ft straight up and pressures of 150psi and more. Northerntool has a 3inch pump for around $600 that is supposed to make such pressures.

    Running dry in a centrifical pump with ceramic seals isnt a big concern I regularly pump my tanks dry and have never burnt out a seal. I dont let them run all day dry, but a few minutes doesnt seem to hurt.

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