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Recent content by Valvecrazy

  1. Valvecrazy

    Geotextile in a water well to prevent sand intrusion.

    I never tried any filter sock or membrane that didn't clog. Sand makes a good media for a filter. I would cap the bottom end of a piece of 6" well casing with .020 slots. Sticking the capped end as deep in the well as possible, I would fill the rest of the well with gravel pack material that...
  2. Valvecrazy

    Resources on Small Distribution Systems with VFD pumps and no distribution tank....

    I would not use one pump for a system that needs up to 1395 GPM yet also needs to produce as little as 5 GPM and maybe even zero flow. I would probably set it up with a 200 GPM jockey pump and a couple of 600 GPM pumps. Each pump controlled by its own constant pressure valve or VFD with...
  3. Valvecrazy

    Resources on Small Distribution Systems with VFD pumps and no distribution tank....

    That would be a hydro-pneumatic tank. What is the max gpm and pressure needed for the system, or what size pumps do you have?
  4. Valvecrazy

    Resources on Small Distribution Systems with VFD pumps and no distribution tank....

    As was said, with a well pump or supply pump that must deliver a constant pressure there is a very limited range where the pump speed can vary at all. Being as power used by a centrifugal pump decreases when restricted as well as when the speed is reduced, a constant pressure valve may be a...
  5. Valvecrazy

    Orifice plate on pump's discharge to allow continuous run

    As long as it is pumping cool water there is plenty of throughput in a constant pressure valve. Just doesn't work with hot water.
  6. Valvecrazy

    Orifice plate on pump's discharge to allow continuous run

    Bladders in bladder style pressure tanks go bad from the bladder going up and down with each pump cycle, which is like bending a wire back and forth until it breaks. Bad tank bladders are a sign of too much pump cycling. Controlling the pumps with Constant Pressure Valves would be an easy fix...
  7. Valvecrazy

    Flow rate change in centrifugal pump without changing impeller size or motor power or motor speed

    Good article. Been around a long time and written with bias. In conclusion we hope that this guide encourages the use of variable speed pumping, in appropriate applications, leading to cost savings from both reduced energy consumption and increased pump system reliability. John Bower Manager...
  8. Valvecrazy

    Flow rate change in centrifugal pump without changing impeller size or motor power or motor speed

    I agree. At flow rates well below BEP a VFD maybe wasting a little less energy than a control valve. But a VFD is not "saving energy" as varying the speed will cause more energy used per gallon pumped, similar to a control valve.
  9. Valvecrazy

    Flow rate change in centrifugal pump without changing impeller size or motor power or motor speed

    There should have been horsepower on that curve, which would have saved you from doing the math or making any mistakes. Because it looks to me like like at 4200 GPM that pump is still 82% efficient not 2%. It is 2% efficient at like 100 GPM.
  10. Valvecrazy

    Flow rate change in centrifugal pump without changing impeller size or motor power or motor speed

    Sorry, I should have said "while maintaining the same head" there is very little difference in energy consumption comparing a VFD to a throttling valve. As was also said, a pump with a more flat curve makes VFD control even less advantageous.
  11. Valvecrazy

    Flow rate change in centrifugal pump without changing impeller size or motor power or motor speed

    Although a centrifugal pump has a range where it is most efficient, it will work almost anywhere along its curve. Restriction on the suction side is not a good idea, and care must be taken to not work the pump at either the extreme right or left side of the curve. But many pumps will work fine...
  12. Valvecrazy

    Replacement bladders for potable water expansion tanks

    Pressure tanks with replaceable bladders are the worst. The bags touch the sides of the tank and cause it to wear more quickly. Diaphragm tanks without replaceable diaphragms are designed so the diaphragm does not touch the sides of the tank and do not wear as fast. About the only thing that...
  13. Valvecrazy

    Replacement bladders for potable water expansion tanks

    Pressure tanks with replaceable bladders are the worst. The bags touch the sides of the tank and cause it to wear more quickly. Diaphragm tanks without replaceable diaphragms are designed so the diaphragm does not touch the sides of the tank and do not wear as fast. About the only thing that...
  14. Valvecrazy

    Pump Power Question

    "Before we begin, understand that the definition of the word law is pretty strong. In its simplest form, the term law means a principle that has been proven to be true for all cases. As we will learn, the affinity laws have limitations. Maybe a better term would be Affinity Guides or Affinity...
  15. Valvecrazy

    Pump Power Question

    All good stuff above. I think there are way too many assumptions made when using the Affinity Law, and we all know what happens when we assume. Lol! I think the biggest use for the Affinity Law is to make people think they are saving energy by purchasing something that varies the pumps speed...
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