Connect Two Pumps in Series?

You will be limited to the head pressure of the last pump in series. If you are trying to get water to travel a longer distance, yes you can do that. I have two 110V pumps on one of my wells, one draws it up 180 feet and places the water in a tank, and the other one draws it another 200 feet across the field, whereas, one pump alone would not work. So, they are not in series like I assume you meant, but depending on your app there's some options.

You will be limited to the head pressure of the last pump in series

????? I disagree, if they are centrifugal pumps and if its in series, yes, also they have to be staged next to each other

Total head will go up, pressure will remain mostly constant.

It won't double the head. You may have trouble. Maybe not.

Or is it the other way round?

Lynlnch is right, like I said the pressure won't go up, phx911 is not right. You will be limited to the pressure of last one. I know this because I tried it !!

i second phoenix911... i have done this many times and he is right

I second phoenix911 again (GA).

It is like a 2 stage pump or a booster pump or a multi stage turbine. They don't even have to be close together.

A centrifugal pump will add its output gain to the pressure at the inlet.

You may have to check the power consumption at the duty point. (lower head = increased capacity and power)

thank you all for your answers ,

but what if the 2 pumps are different , I have one installed pump (2 HP) and the guage is giving 2.2 Bar at the outlet and from the curve this will meet 75 GPM , the second pump which I want to install is 1HP (just to increase the head) and in it's curve 75 GPM ( the outlet of the first pump) will meet 15 M head , so I wonder if the head will increase 15 M or not ?? I don't know I'm afraid that this will make cavitiation to the second pump ??? any help ??

If the higher stage pump is grossly larger than the first, cavitation is likely, but I don't think so in your case. It will add 15m to the total head, or nearly that. A full evaluation would require the curves of both pumps and the configuration of the piping.

Thank you for your answer,

the pump curve is in the page number 2 of this PDF link :-

http://www.staritepool.com/pdfs/dynaproDS.pdf

the first pump which I'm using is pump G (2 HP) and the second one is pump F (1 HP) , so can you give me your opinion ??

thank you for every one ...

Even if the pumps identical and volumes outputs is the same, that is only theoretically on the pump curve. .rarely do you get the same output on the same size/types of pumps because of age, motor cut have as much as 1-2% difference in rpm, or even the impellers are cut down ^{see note on bottom}. And if not on a VFD......which I can assume not.

I always prefer to put the higher volume pump "a" first and put the lower pump "b" last and let the first it dead head. That way you will unlikely to cavitate because your always stuffing the pump.

The confusion with the other guest OP is that the volume will be at the lowest GPM not the pressure.

^note;

^{The things that could occur is if the impeller is cut down is that the motor could over current,}

p911

I'm the same question asker but after regisitration ,

so do you think what you have mentioned will be the case in my pumps ( the previous attached PDF ? )

and if the first pump is giving 2.3 Bar then can I know exactly the flow from the curve of the pump and can I trust this number of flow ( from the curve ) ??

about the volume , I think the outlet volume of the first one ( the bigger) will be the inlet volume of the second one so it will work on the bigger volume not the smaller ?? and I think there should be a point in the curve of the second pump having the same flow of the outlet of the first pumo in order to work properly but if there is no point of flow in the second pump curve then it will not give any head ?? is that right ??

Welcome to CR4. The pump curve is only used for estimating, there are factors that are usually would have nominal effect. But if you have pumps that are close to the same output, It does not take much for a pump to cavitate and tear itself up.

But yes have used the pump curve as a rule of thumb, I have trusted the curve.

You are asking some really good questions.

and I think there should be a point in the curve of the second pump having the same flow of the outlet of the first pump in order to work properly but if there is no point of flow in the second pump curve then it will not give any head ?? is that right ??

This is getting into important technical aspects. I can see your question. i.e.words the 1st pump would be pumping through the second without value added pressure.

I not a pump expert, but I have worked with them enough 10-15 + years in the dairy industry. Yes the pumps output head is in reference to the input, thats where you start.

And at times I would have problems, the problems would basically be overcurrent in the pumps, (motors begin acting like generators) when this happens what I have done is after the second pump you control the outlet with an orifice to restrict the flow to the lower pump capacity, and make the second pump work. and this could just be a valve so you can adjust out flow, just keep in mind that there can be pressure loss here in restricting the flow, but that can be nominal, I suggest a gate valve. This you would be able to makeup in an piping characteristics.

otherwise look at it as just adding to the pressure (sum of head of the two pumps). Not knowing your piping, I would try it without the orifice first, then add the valveif having trouble.

p911

A high head (= pressure x 2.31 if measuring in feet and psi) multistage centrifugal pump is several pumps in series within the same housing. The head (pressure) increases by relatively small amount from one stage to the next, but the total is additive or nearly so.

Put gauges on the inlet and outlet of the last pump. The head (pressure) will be seen to increase.

A lot depends upon the pressure/flow characteristics of the piping system in which they are installed.

Hi alaa riad - Welcome

Getting two self priming pump systems primed properly will be difficult if the smaller pump is first.

The smaller pump will be pumping air onto the suction tank of bigger pump and actually force the water out of the tank. and you will be left with a pressurized air bubble. You may need a air relief vale at the suction of the top pump.

Bigger pump should be first.

Check for leaks on the suction line!! PVC pipes and suction pipes do leak!!

thank you guys for your answers ..

but I recieved today an email from the manufacturer saying that .

YOU CAN'T CONNECT 2 SWIMMING POOL PUMPS IN SERIES IF THE PRODUCED PRESSURE WILL BE MORE THAN 50 PSI ( AND THIS IS MY CASE)

he said that if we do so , the second pump will leak because all the swimming pool pumps have been tested with maximum pressure of 50 PSI .. so I think this is a good information for all ... many stores buyers told me that I can connect them easily and the pressure will be more without mentioning the point of pressure .. so the best solution for this is to put a booster pump after the swimming pool pump.

Hi alaa riad

You did not mention any leak in any of your posts.

Would like to know (out of own curiosity and future reference) where the leaks are.

Does water squirt or ooze out or is it sucking in air?

Dear friend

Yes. You can put pump in series, provided the pressure suitability aspect/strength of the pump parts/casing of the succeeding pump(s) is taken care.

DHAYANANDHAN.S