Pond Boss Forums GENERAL QUESTIONS Help Challange the expert

Hi guys, i have a challange for pump or contractor specialist,

I have a case to choose the right pump for irrigation. very well ,how can i choose the right pump if they want to use pvc pipe with total length of 14107 feet, the capacity what im asking are 4755 USGPM and i still cannot calculate how much psi that i need to fill the pipe till end of pipe. The rivers depth are around 23 feet to 33 feet. The problem is how to design the pump and how many pump i have to use along the pvc pipe, but please consider that the maximum pressure for pvc pipe are 116 psi. Thanks guys, any suggestion?? can someone have any idea what kind of pump i have to use ??? the pump suction are from the river with depth more than 23 - 33 feet. If possible any suggestion to get the water at end pipe??? is it possible if we use several pump in the middle of the pipe to boost the flow rate???

Howdy, DGM, and welcome to the forum. I'm pretty sure your are the first poster from Indonesia, in general, and Java (?), in specific.

To convert your units to stuff poor old English unit users like myself are more familiar with:

20" pipe at about 120 psi max pressure, pipe length = 4107 feet.
Desired flow rate = 79.25 gallons per second = 4755 gallons per minute.
River (source) depth in excess of 23 feet.

Please check in here periodically, as the pumping experts may have some questions to ask to clarify your situation in their minds.

Hi DGM and welcome to Pond Boss!

We'll need to know the head... how high above the river the water must be lifted. That makes a lot of difference.

That sounds like an awful lot of pressure in such a large (20") pipe. I don't think you will need nearly that much pressure to acheive a 300L/Sec flow rate.

I have no idea what size pump but it's gonna be BIG!

I hope you'll post picks when it's installed and running!

Welcome, and glad you joined us DGM!

Yes, just filling a 20" pipe takes a big pump. But the pressure won't have to be very high at all, nowhere near the 120psi maximum. Just to show you how much water a 20" pipe can carry, just a 1' siphon head can flow water at 1250gpm! Probably 5 pounds of pump pressure could easily flow the required 4800gpm, depending on the head.

Thanks to all of you, i know this is a big project it is to me. You are right Theo, i forgot to use a simple fraction, and i already corrected. Any suggestion what kind of a design?? may i place 2 or 3 pumps in the pipe line to boost the water in case the pressure and capacity didnt reach at maximum or if we gonna lower the main pump pressure. Thanks....



Silent is gold........ but please shout on this one.........

Here are a couple manufacturing sites for municipal water supply pumps.....expect pricing to be well over $100,000 USD.

http://www.water-technology.net/contractors/equipment/hyosung/ Seoul S. Korea

http://www.acpump.com/ ITT corp. USA

Thank you all with your information very helpfull for me. but i still cant choose the pump head, Mr. boobad can you please specified how much the total head that i need accourding to your experience. and is it possible if im using the vertical turbine pump as the main pump. Thanks.

I don't get it. I don't see any reference to a 20 inch pipe anywhere. Do you already have the pipe and if so what size is it? You really don't want to buy the pipe until you pick the pump although if you already have 20 inch it will work. Too big is better than too small. The most important things to know is pipe size (determined by pump manufacturer), pipe length (14,107 feet), and the height of lift from the waters surface to the pump, and the height of the highest point the pump must pump the water up to. I think this is all you need and you can size a pump. It doesn't make any difference how deep the river is where you get the water. Make sure you get a continuous duty pump. It will be a big pump and it will be an industrial sized very expensive pump. Might need a 10 inch pipe or so. Do a google search for dewatering pumps. This will get you to the companies that make the big diesel powered water pumps used at construction sites that are made to run around the clock. Then contact those that sell them and give them the data above and they'll tell you which one will work. Don't try to pick it yourself, ask them to help, that's what they do.
Here's a company that makes what I'm talking about:

http://www.completepumps.com/trash.htm

They have a pump that has a 12 inch outlet that pumps 6000 gpm.

Good luck and I hope you have plenty of money.

DGM removed the 20" reference when editing his first post.

Dmg,welcome aboard.As far as help,Iagree with BZ 100%.Talk to the people who sell the pumps.Have all you info,such as distance and lift.This is what they do,so let them do it.No need to second guess yourself.I would talk to more than one company too,just to be sure I wasnt being"oversold".Good luck,and let us know how you make out please.

Thanks guys, maybe i can clear it like this :

Pipe length are 14107 feet with diameter 16" or 20" pipe material is PVC with maximum pressure allowed 116 PSI, the capacity what im asking are 4755 USGPM and total Head = ???
along the pipe there are 3 gate valve to water the plant.
The elevation ground are about 17 feet from the pump to the end of pipe. The length of suction pipe are 22 feet from the pump. and the question are how you calculate how much pressure the pump need, is it possible if i place 2 or 3 pumps along the pipe to boost the water with this design maybe i can lowered the pressure. Can the design work? the main pump i use a horizontal split casing pump (Flow rate: 4755 USGPM, pressure 21.8 PSI), material cast iron, impeller bronze, standard.
the booster pump i use the centrifugal end suction pump (Flow rate: 2.38 USGPM Pressure 58 PSI). Thanks.

By the way i had some answer, please read and tell me how it does and what do you guys think off, Thanks.
Valveman : The class of the pipe will still make a difference. I will use class 235 for a worst case scenario. With 16" pipe going 14107' at 4800 GPM, you loose .46 PSI per 100'. That would be 65 PSI plus the lift of 17' which is another 7 PSI. 72 PSI is a total head on the pump of 166'. So your pump would need to deliver 4755 GPM at 166' of head, not counting any suction lift.

With 20" pipe, the pump only needs to deliver 4755 GPM at 68' of lift. This will take a pump with a little over 80 HP for 20" pipe, and a little less than 200 HP for 16" pipe. As always, the best way to save energy is to use larger pipe.

A single pump will do, as even with the 16" pipe, the max pressure on the pipe line will be about 72 PSI. The velocity in 16" pipe will be 8.19 FPS, and with 20" pipe would be 5.31 FPS. You are going to need to use the 20" pipe.

A standard 20" tee is like adding another 25' of pipe. A standard 20" elbow is like adding 50' of pipe. And a 20" gate valve is like adding 12' of pipe. Then the friction loss and head for the pump figured will not give you any pressure at the end of the line. If you are just dumping into an open tank, this should be all the head you need. If you need pressure at the end of the line, you will need to add the additional pressure required.

I would use a gate valve on the discharge of the pump. Start the pump with the gate valve closed or almost closed. Then slowly open the valve to fill the pipe line. If you just turn on the pump with no valve, or no water in the pipe line, the pump will not have any head against it. This will make the pump produce too much water, too much velocity for the pipe, and possibly even overload the motor. Once the pipe is full and flow is moving, you can open the gate valve all the way. The pipe is what puts the head on the pump. If you turn on the pump into an empty pipe line, there is not enough head, so the pump will produce too much flow and use too much horse power.

A soft start on the motor WILL NOT be slow enough to get the pipe line full before the pump goes to full speed. A VFD cannot speed the motor up slowly enough to work. Even when the pipe is full of water, you need to start the pump against a closed valve, and slowly open the valve to prevent surge.