electric water pump sizing irrigation

[kannot]

I need to irrigate my land from my lake I have about 160 trees (ornamental) all fed by sprinklers, 10 sprinklers per outlet, my lake is 1 rai in size I currently use a Honda wt30 water pump which is fine for about 25 sprinklers ( 36 psi at max speed) running at once but I want to swap to an electric water pump with higher psi 50+ would be good.

The water will be lifted from the lake about 1 metre maximum from water to pump and then up to a total of about 4-5 metres head to the base of the trees.

All water is pumped down one inch pipe ( which I cant change) so loss has to be taken into account and there are several 90 degree bends etc, total length is about 80 metres maximum at the farthest point from the pump some will be less than 20 metres.

It has to be single phase only..........any recommendations on size/brand in Thailand, price doesnt matter as long as its reliable, the water is fairly clean, looking to run as many sprinklers as possible at one time, 30 would be good.

1hp 2 hp?

Not sure if it belongs in diy or farming forum Thanks

Edited June 2, 2016 by kannot

[Crossy]

The WT30 has a 3.6kW engine according to this site http://www.hondaenergy.com/water-pumps/honda-wt30-3-inch-trash-water-pump.html#product_tabs_product_features

That equates to about 4.8HP! A pretty big electric pump, certainly bigger than anything readily available in single-phase (biggest SP pump I've seen is 3HP, we have one).

Do you have 3-phase power available at the pump site?

I suspect you're looking at two 3HP pumps

[kannot]

The WT30 has a 3.6kW engine according to this site http://www.hondaenergy.com/water-pumps/honda-wt30-3-inch-trash-water-pump.html#product_tabs_product_features

That equates to about 4.8HP! A pretty big electric pump, certainly bigger than anything readily available in single-phase (biggest SP pump I've seen is 3HP, we have one).

Do you have 3-phase power available at the pump site?

I suspect you're looking at two 3HP pumps

Thanks but thats not the Thai model, the Thai model has a 160 cc engine as opposed to 240 cc if that helps?

No 3 phase available

This is the correct pump

http://powerequipment.honda.com/pumps/models/wb30

Also found this which states 3,6kw same as gx240

http://engines.honda.com/models/model-detail/gx160

Sprinklers are not the rotary type they are the spray type at ground level, Ill try to find the delivery rate for these when Im out next

Edited June 2, 2016 by kannot

[kannot]

OK the head of the system will be 3.5 metres at the highest above the pump, just measured it, and the pump will have to lift the water not more than 1.5 metres dry season to half a metre wet season.

[CGW]

Pump you have has an output of 290 gpm, probably with O head, so you need something larger running off single phase (excuse me, I'm talking to myself!) if there is a pump that is capable of that, the head and lift, the friction losses and pumping head would be inconsequential, does such a beast exist?

[kannot]

Pump you have has an output of 290 gpm, probably with O head, so you need something larger running off single phase (excuse me, I'm talking to myself!) if there is a pump that is capable of that, the head and lift, the friction losses and pumping head would be inconsequential, does such a beast exist?

There seems to be quite a lot to factor into the equation, I dont think Ill need that sort of "flow"output, Honda also make a petrol high pressure model but i dont see it for sale in Thailand .

Im going to find out the flow rate of the sprinkler heads, they are only small I looked at one website and it stated 40-60 litres (13 gallons) per hour per sprinkler head and mine look identical to those.

For 30 heads on at once that would be a max of 395 gallons an hour so the 290 gallons per minute from the petrol pump I have now is way over the top for what I need.

The petrol pump I have is high flow (as its a trash pump) but low psi I can manage with much much lower flow but higher psi looking at the figures. Ive used the 13 bar rating pipe so pressure shoudlnt be an issue.

Guess Ill have to sit down and go through the figures once I get the sprinkler lit/hour rate and go from there, these arent massive sprinklers the water goes down one inch pipe to within a metre of each sprinkler then down to half inch then finally down to that small bore plastic pipe about 6mm but from the large 1 inch to the actual sprinkler head is not more than 1 metre downsizing.

So to sum up I have a total head of 4.5-5 metres from water level 1 metre of that will be the lift of the pump.

30 sprinklers at 13 gallons an hour each am looking for about 50psi at the sprinkler heads.

The time the sprinklers will be on for is not more than 10-15 minutes a day.

I think a much smaller electric pump will do it as I dont need that 395gallons per minute at all

Edited June 2, 2016 by kannot

[CGW]

Have you looked at Hitachi WM-P400GX? I would imagine it would be up to the job. Constant flow rate or high pressure adjustable.

[kannot]

Have you looked at Hitachi WM-P400GX? I would imagine it would be up to the job. Constant flow rate or high pressure adjustable.

Will have a shufty as they say thanks.

[kannot]

This caught my eye in the English manual 56l/min is the 400 model 70l/min the 750 model my supply distance will be about 85 metres am just wondering how much that L/min will drop over that distance?

WATER VOLUME (LITRES/MINUTE)

:

(AT A TOTAL SUPPLY DISTANCE OF 12M) 56l/min 70l/min

[CGW]

Is there no flow chart with the pump manual? it should give you different flow rates with different heads, frictional pressure losses over 85m would be ~14psi.

[kannot]

Is there no flow chart with the pump manual? it should give you different flow rates with different heads, frictional pressure losses over 85m would be ~14psi.

Been looking cant find one yet found this info but more bad news my measurement was way out with length of pipe its going to be more like 140 metres length and if we start at 70 psi with the bigger model the 750 gawd only knows what will trickle out of the end of 140 metres, the head height is only 3.5 metres though.

Whats the frictional losses at 140 metres? I like the idea of the all in one unit though which adjusts the pressure as to whats open.

[In the jungle]

There is a very useful website called Irrigation Tutorials. Google will take you to it.

It will help you a lot with pump sizing and system design issues.

[CGW]

^^ best case would be a psi loss of ~25 psi, thats a rough calculation. then you still have to lift the water 5m, thats another 7 psi or so? sounds minimal? don't know anything about sprinklers!

[kannot]

There is a very useful website called Irrigation Tutorials. Google will take you to it.

It will help you a lot with pump sizing and system design issues.

Yes thanks already looked at it before posting, it gets quite complex.

[kannot]

^^ best case would be a psi loss of ~25 psi, thats a rough calculation. then you still have to lift the water 5m, thats another 7 psi or so? sounds minimal? don't know anything about sprinklers!

Thanks............ would bring 70 down to around 40 which is 2.6 bar bar which should be ok, I still have to drive to Thai watsadu to check the sprinkler flow rate which i saw once before on the shelf, at a push 20 sprinklers could be open instead of 30 at any one time as there are roughly 10 per circuit.

Edited June 4, 2016 by kannot

[kannot]

^^ best case would be a psi loss of ~25 psi, thats a rough calculation. then you still have to lift the water 5m, thats another 7 psi or so? sounds minimal? don't know anything about sprinklers!

Thanks............ would bring 70 down to around 40 which is 2.6 bar bar which should be ok, I still have to drive to Thai watsadu to check the sprinkler flow rate which i saw once before on the shelf, at a push 20 sprinklers could be open instead of 30 at any one time as there are roughly 10 per circuit.

I think Im going mental the figure "70" is the lit per minute not the psi

Its got a maximum rating of 55psi on Hitachis english brochure so with the sort of losses you mention Im going to be down to low I think.

Reckon it will end up being a big 1.5hp pump required.............which brings me to the next question??? hahaha a controller Ill need it to switch on and off when each sprinkler zone is opened up etc

Edited June 4, 2016 by kannot

[kannot]

Found the chart for the Hitachi pump

"If "the sprinklers use the amount each that i think they use it works out about 7 gallons a minute or about 32 litres for 30 sprinklers a minute which is well within the Hitachi 750 range max 70l minute

Also found the friction loss chart for this 1 inch pipe and at 7 gallons a minute = a loss of 1.4 psi per 100 ft (30m) which is better if correct? means a loss of 7psi + head loss. another 7 = 42psi ?? or am i missing something??

the 750 model pump has 56psi max pressure on "H" high setting

Edited June 4, 2016 by kannot

[kannot]

Heres the pump manual in English

Hitachi WM-P400_750GX_En.pdf

[CGW]

The way I look at it is this:-

From the table for frictional losses you would have to start with gpm at the pump which is 70 l/m = 15 Imp/g

5.5 x 140m = 24psi + Hyd head ~7psi = 32 psi or thereabouts psi loss, if you start with 56 psi - 32 psi = 24 psi available at sprinklers? I may well be wrong as I am old now! but without pulling a ton of books out and spending hours calculating this is a rough rule of thumb calc, without taking a lot of other points like elbows, temp, vis into account.

[BHW]

How much does each tree need, have you thought about a solar pump.

[kannot]

The way I look at it is this:-

From the table for frictional losses you would have to start with gpm at the pump which is 70 l/m = 15 Imp/g

5.5 x 140m = 24psi + Hyd head ~7psi = 32 psi or thereabouts psi loss, if you start with 56 psi - 32 psi = 24 psi available at sprinklers? I may well be wrong as I am old now! but without pulling a ton of books out and spending hours calculating this is a rough rule of thumb calc, without taking a lot of other points like elbows, temp, vis into account.

Thanks Im off to Thai watsadu today to check the flow rate of the sprinklers and then to sit down and calculate everything involved exactly.

As for solar Im not sure this could provide the ooooomph necessary.

[kannot]

Ok got the figures now, just to add that friction losses will be dramatically reduced as on measuring the internal diameter of the pvc 1" pipe i find its 28mm!!

Total pipe length (1 inch diameter BUT internal diameter is 28mm) to farthest sprinkler from pump160m (some will be 50 metres nearer the pump) almost all straight runs 4-5 ....90degree turns on the way

Total head 5.0metres from water level 4.0 metres from pump level

Sprinkler flow rate between 80-120 lit an hour so Ill take 100lit/hour as a guide, thats 22 gallons/hour or 100litres an hour per sprinkler

1 sprinkler will use 1.6 litre/minute or 0.35 gallon/minute

20 sprinklers will use 33.2lit minute or 7.3 gallons minute

30 sprinklers will use 49.8 lit/minute or 10.95 gallons/minute

The Hitachi wp750 gx pump specs are at this head height of water looking at the chart about 78l/minute so flow is more than adequate but what will the psi be after all losses?

If necessary i could always open just 20 sprinklers per time but the 30 would be good.

Edited June 6, 2016 by kannot

[kannot]

double post

Edited June 6, 2016 by kannot

[CGW]

Just checked the id of a piece of 1" pipe I had laying around and sure enough the id is 28mm! strange, never worked with UPVC, sure they have a reason for this?

To calculate total pressure loss you need to know the total flow area at the sprinkler, (the diameter of all the holes added up) the calculation is a bit long winded, you may be able to find a spreadsheet online to help, your doing well so far.

Sounds like it will be ok? given that your options start to get complex.

Good luck.

[kannot]

Just checked the id of a piece of 1" pipe I had laying around and sure enough the id is 28mm! strange, never worked with UPVC, sure they have a reason for this?

To calculate total pressure loss you need to know the total flow area at the sprinkler, (the diameter of all the holes added up) the calculation is a bit long winded, you may be able to find a spreadsheet online to help, your doing well so far.

Sounds like it will be ok? given that your options start to get complex.

Good luck.

Yeah i think I might risk it, I also have an option to move the pump way nearer the sprinklers which would cut friction loss down to 5psi but will involve a longer power cable to it and some digging and I think this is the option Ill take.

Thanks for your time by the way

[Nellie]

At least once you can check this given link. Because here you can see many sprinklers pump related to your criteria. 

https://www.smartsprinklercontroller.com/best-sprinkler-irrigation-pumps-reviews/