What size electric motor for my irrigation pump

[canuckamuck]

I have a piston pump, a bigger one, about 36,000 liters an hour. I was going to get a diesel motor for it, but I am thinking now I want to go electric.

I know nothing about electric motors other than they run when you turn em on.

I have two questions:

1 how do I choose the size?

2 how do I figure RPM's and get the right pulley combo?

[sezze]

Whats the size recommended by the pump ? If you have the brandname and type of pump maybe i can look it up on the internet . Also , it says how many rpm it needs , and most electric engines run at the same speed , so you can calculate the pulley needed .

[sezze]

Whats the size recommended by the pump ? If you have the brandname and type of pump maybe i can look it up on the internet . Also , it says how many rpm it needs , and most electric engines run at the same speed , so you can calculate the pulley needed .

[green thumb]

Found this on the net that might help. You can play with the numbers.

 

http://irrigation.wsu.edu/Content/Calculators/General/Required-Water-Pump-HP.php

[canuckamuck]

@sezze It is a Chinese pump, it has some logos on it, but  I could not find the pump on the internet. It is the basic piston pump style you see in Thailand. It is a two inch pump. At one shop they were recommending a pump with greater than 10 hp, but another shop was certain a 5 hp pump would have no trouble. But these were gasoline engines.

Do HP numbers mean the same thing in electric motors as they do in gasoline engines? Because a 5HP electric motor needs 3700 watts which has got to be expensive, but a 5 hp gasoline motor runs pretty cheap.

I always thought electric was more efficient for pumps. Maybe because they have more torque you can use less HP?

 

[Crossy]

Electric is more efficient in that it will be cheaper to run.

 

BUT

 

A 5HP motor is unlikely to be available in single-phase (do you have a 3-phase supply?) and it will of course need a cable (how far from the supply is the pump?).

 

In reality, the portability and lower cost of a liquid fuelled pump (petrol or preferably diesel) would offset the reduced running costs of electric.

[canuckamuck]

Don't have three phase available, so that simplifies things a lot. I will go back to a gas/diesel solution. Thanks

[In the jungle]

In Pathumthanee which is North East of Bangkok the weapon of choice for shifting large volumes of water, such as the 36 cubic metres/hour you mention, is the Kubota single cylinder diesel engine (or clone thereof).  It makes about 12 horsepower and has a massive and scary looking exposed flywheel.  The most common scenario is pumping water from an irrigation canal into paddy fields in combination with what looks to be a crude version of an Archimedes Screw pump which is driven by belt. 

 

You can see a variety of these engines on Kubota Thailand's website.  From memory at least one version is hand crank start only which wears me out just thinking about it.

 

You also see Archimedes style pumps driven by old diesel truck engines which I assume come from a scrapyard.

 

Gas engines are also used but they are in the minority.