# Thread: Reference or calculator for sizing of suction pipe

1. ## Reference or calculator for sizing of suction pipe

I am trying to figure of what intake hose sizing I may need to a pump that pumps at much higher flow rates than normal pool pumps. The pump is to be used to basically empty the pump, such as a gasoline powered water pump. I may need to run a long length of suction hose to accomplish what I am trying to do. So, is there a simple online calculator to do this? I assume this is the sort of calculation that is done all the time in calculating total dynamic head. I do not want to create cavitation and I do not want to unnecessarily use a larger diameter suction hose than what is necessary. Thanks.

Del

2. ## Re: Reference or calculator for sizing of suction pipe

There are head loss tables such as the one in the Hydraulics 101 sticky or this one: PVC Pipes - Friction Loss and Flow Velocities Schedule 40

But none that I know of will suggest a pipe size. If you can give some more details, I might be able to help.

Does the pump have specs which dictate how much suction head it can support?

Make/Model of pump?

Distance you are trying to pump?

Approximately flow rates (GPM)?

Vertical lift (ft)?

What type of pipe are you planing to use (e.g. schedule 40 PVC)?

3. ## Re: Reference or calculator for sizing of suction pipe

For example, lets assume that I want to pump 666 gallons per minute. Let's further assume that I use a gasoline powered pump that can pump this much, as I do not have anything specific in mind yet. Let's also assume that it will need to be pumped up a 5 foot elevation and the length of the suction pipe is 100 feet long. If you need to plug and chug some diameters, then 4 inch ID would be a starting point. You can also run it at 6 inch ID if 4 inches fails. Thanks, and I will look up the references you provided.

4. ## Re: Reference or calculator for sizing of suction pipe

Without detailed knowledge of the pump it is just guesswork but you would need 6" pipe to have than 8 ft/sec water velocity. You might be able to get away with 4" but again, it depends on the pump.

The discharge side of the pump can also make a difference. Throttle the discharge and the pump is less likely to cavitate. However, you might not get 666 GPM then.

This is really a system calculation. You cannot determine one piece without all the other pieces.

5. ## Re: Reference or calculator for sizing of suction pipe

I have more homework to do. The outlet would probably be 4 inch pipe, 100 feet of length with either no elevation difference, or perhaps up to negative 5 feet of elevation. Thanks for much, mas 985.

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