How to Size Motor Pumps

in elevator it is impossible to use single phase motors.because in elevator your load will be more so the motor size.mostly it will have VFDS in elevators.cost wise also three phase is economic i suppose.

The motor is to be use in pumping water in an elevation af 200mtrs. Not for elevator

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Is this a pump? If so, how many gallons/liters per minute do you need to pump? From that, we will know the HP or KW required, and then can determine if a 240V 1-phase circuit can handle it.

Yes it was. A motor to be series in a pump. 10GPM is good enough. Kindly please help

The duty requires a shaft power of 460W (assuming Imperial gallons) so it is well within the capabilities of a single phase pump, though clearly the motor will be bigger than that figure.

Try contacting some pump suppliers for further advice.

This will require about 2 to 2.5 HP, depending on pump efficiency. The next largest standard motor would be 3 HP. On a 230/1/60 circuit, this would be about 8.3 amperes. I'm not sure, but such a single-phase motor ought to be available.

Dear this depends on the efficiency of the motor, in general take it as 70%,there fore Power absorbed(kw) = Q(m3/hr)*H(m)/367*eff = 2.27 * 200 / 367*0.7 = 1.76 kw.

adding 20 % safey so that the motor can cover the whole pump curve not only the duty point there fore 1.76 x 1.2 = 2.112 kw.

you can find 2.2 kw (3 hp), 3 ph , 3500 rpm,motors in the market.

Your would need quite a bit of pressure to overcome head.

Over 1500 psi (105.45 kgs./sq. cm.)

And this does'nt include check valves

With a single phase supple, You may need to stage pumps in series,

Is this potable water?

p911

1500 PSI? Smoking what today?

My math says 200 Meters is about 656 feet and gravity seems to want to make 1 foot of water coulomb produce around .43 PSI. My math seems to point to 283 PSI static.

Factor in the correct size of line and its flow losses plus some good head pressure (40 - 50 PSI working pressure at the end) and I cant get much past 350 PSI on one inch line with a 10 GPM flow.

My books seem to agree on a standard issue multistage 3 Hp single phase pump being more than adequate!

my mistake I used 2.31 by mistake (2.31 ft = 1 lb) inverse of 2.31 is 0.43 lbs per foot also. too long a day. I actually should be smoking something, pass the pipe

Well he should be using a check valve and that should give some resistance

p911

All of the common check valves I have ever used have at best a 1 PSI flow restriction at normal flow rates. Usually they don't get factored into a systems pressure drop numbers.

Can you feel the difference in your shower pressure if its 49 PSI instead of 50?

Great answer

Carel,

Are you sure of the water flow?, 10 gpm is roughly 38 liters per minute..? ( sounds too less to me..)

Anyway, if you think that flow is enough then you require a 2kw 230 vac 60Hz pump which can deliver at at 20 bar pressure.

cheers..

are you sure that only 2kw could pump a 10gpm from a 200mtrs elevation.?in what specific size of pipe must be use.? I think 2kw is too small

So, armed with what has been offered here, can you now order a pump/motor that will do the job?

No. You cannot.

If you are going to purchase a pump/motor from a recognized pump/motor supplier, and not from the black market, they will be able to suggest a product from their line of available pumps/motors.

Put all the requirements in an e-mail, hopefully more complete than the information presented here, and submit it to three pump suppliers and see what they have to say.

But if the reason you asked this in the Electrical engineering forum, as opposed to where the pump people hang out, is because you wanted to know if you needed a VFD and a 3 phase pump, the answer to that question is...

No.

Whether you end up with 2HP, 3HP or even 10HP, the power from the motor is the same, single phase or 3 phase. The only reason to use a VFD is if there is some advantage to having variable speed. For example, if you are lifting the water just top put it in a tank, variable speed does nothing for you except waste energy. if on the other hand you need to match flow and / or pressure for a process and would do that with a flow or pressure restriction device, then a VFD will save you energy in the long run, usually enough to pay for itself.

Actually, JRaef, a second valid reason to use a VFD is to allow a 3-phase motor to be powered from a single-phase source. This is often done when the needed equipment is not available with a single-phase motor. Unless a single-phase motor/pump combination is unavailable in the OP's location the answers against a 3-phase motor and a VFD are well said.

Regards--JMM

pl. visit ww.texmo.com site which are having all details

Dear this depends on the efficiency of the motor, in general take it as 70%,there fore P(kw) = Q(m3/hr)*H(m)/367*eff = 2.27 * 200 / 367*0.7 = 1.76 kw.

adding 20 % safey so that the motor can cover the whole pump curve not only the duty point there fore 1.76 x 1.2 = 2.112 kw.

you can find 2.2 kw (3 hp), 3 ph ,3500 rpm, motors in the market.

Dear I have checked again, now there are some points you have to consider, for low flow pumps usually the efficency is low so you have to consider it less than 70 %, so we will consider efficiency as 45 % and this is very logic if you check all the pumps catalogues for any manufacturer.

so that calculation will be: P(kw) = Q (m3/hr)*H (m)/367*eff. = (2.27 * 200)/(367*0.45). => P(kw) = 2.749 kw, now this is very important to take in consideration that the motor should cover the whole pump curve not only the duty point so you have to add 20 %, => p(Kw) = 2.749 x 1.2 = 3.3 kw.

note that i converted 10 US gpm, to M3/hr.please check the attached pump curve.

motor avialable in the market are 4 kw, 220v, 3 ph, 60 hz. prices about: 400 US $ /each motor.

now regarding the control if the pump will work as a transfer set, i advice you to go for D.O.L control which is simple and very cheap compared to VFD and D.O.L control panel can satisfy your needs, becasue in the case of transfer from tank to another one you dont need VFD.

for pumps with huge flow you can go for high efficiency like 75 %, or 80 %, but for small pumps flow in general the efficiency is low.