Pump inlet/outlet?

[Dave H (MI)]

I am making a water tender to feed my sprayer. I have been offered a pretty nice pump but it has 3" outlet/inlet. My tank and all my houses are 1.5 inch. I am thinking I need to pass on the pump or re-plumb everything. Would it cause problems to reduce the inlet and outlet on the pump instead?

 

[Bob]

What type of pump, turbo? centrifugal???

 

[Jtex]

you can reduce the discharge but the suction line must be as big or bigger than the pump suction size, if not the pump will cavitate and cause you damage to the pump

 

[old]

Last yea I installed a pump on a sprayer unit and the pump had 2 inch inlet/outlet but the hoses where 3/4 inch and it works just fine with me reducing things

 

[Russ from MN]

I'm assuming it's a centrifugal pump, if not disregard! Most centrifugal pumps will only pump as much liquid as you give them, so the smaller pipes should not be a problem. If it's a high performance pump like a fire pump then you may have a problem. I'm also assuming it is run by a gas engine that you could run a little slower.

 

[Dave H (MI)]

It's the typical pump you would see at the hardware with a Honda engine on it. I am assuming it is centrifugal. Not positive.

 

[Dave H (MI)]

The thing about cavitation has come up in some of my research. The damage part I did not know. That is what I was worried about.

 

[Indiana Ken]

(quoted from post at 09:29:22 05/12/15) I am making a water tender to feed my sprayer. I have been offered a pretty nice pump but it has 3" outlet/inlet. My tank and all my houses are 1.5 inch. I am thinking I need to pass on the pump or re-plumb everything. Would it cause problems to reduce the inlet and outlet on the pump instead?

I am assuming by "offered" you mean for free. You do not want to restrict a pump on the inlet side, instead restrict the outlet side to reduce the flow rate to the range of a 1.5" inlet pump. The discharge pressure will increase however, most of the agriculture centrifugal pumps are low pressure and it should not be a big deal. To clarify; the inlet plumbing can be 1.5" however, the flow rate must be reduced such that the 1.5" inlet plumbing is not the restriction.....restriction must be on the discharge side.

In this application it would be best to run a flooded suction which, means the pump inlet is below the bottom of the tank. In addition you can generally run the engine at less than full governed speed which also reduces flow and pressure.

I recently bought a Pacer Ag pump. My paper work shows the flow curves for various impellers that are available for the pump. Assuming your pump has optional impellers available fitting the lowest flow/pressure impeller would also be avantageous (but not required) for your application.

 

[Dave H (MI)]

Never assume...the guy wants a fair price for it.

 

[Indiana Ken]

(quoted from post at 19:07:42 05/12/15) Never assume...the guy wants a fair price for it.

Well, in that case why not buy the size you need. I paid $239.99 for a Pacer Ag Pump with a B&S Intek 550 at Rural King, last fall. It has 2" inlet/outlet. I run a 10', 1.5" suction line (all straight fittings, no ellbows) and 1.5" discharge line. I am very happy with the way the B&S starts and runs.

 

[David G]

I would totally agree

 

[showcrop]

As others said inlet is what you need to be concerned about, but remember that the concern is friction loss, and friction loss is a function of distance AND flow rate. If your length of suction can be reduced from a standard approx 10 ft to say 6-8 feet you can stick with your smaller diam suction. In addition, since the pump is larger than what you had, you have no need to go after a very high pumping volume, so you can let it loaf along and there will be no need for concern about cavitation.

 

[Butch(OH)]

In the ideal world its not the best practice but in real life the short answer is no, it wont hurt anything. Just run the engine RPM only high enough to get the job done, probably not over half throttle. Its not like your in a 24/7 application.
At the farm where I dont have a well I have for years run my pressure washer from a tank of water in the back of a pick up. The HP pump doesnt like only having a small amount of head from the tank so I place my 2" Honda powered pump between the tank and pressure washer with 3/4" garden hose and run it just above idle. Has run that way at least 100 hours with no ill affects noted.

 

[David G]

Yes, reducing RPM will reduce the inlet requirements.