View Full Version : Challenge the expert

12-05-2008, 03:10 AM
Hi guys, i have a challange for pump or contractor specialist,

I have a case to choose the right pump for irrigation. very well then but how can i choose the right pump if they want to use pvc pipe with total length of 14107 feet with diameter of pvc pipe are 20 inch, 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??

12-05-2008, 04:13 AM
I would guess this is well beyond the scope of plumbers on this board ... you need to work with an engineer who has experience designing water systems of this magnitude. Good luck

12-05-2008, 04:27 AM
That is almost 6,000 gallons per minute. Assuming you are just dumping the water into an open area, so there is no backpressure at the end, the pressure you will have overcome will all be from friction loss and elevation. As the velocity increases, the friction factor also increases. There is a point when the friction loss will exceed the pump's capacity, at which point the flow is at its maximum. You have to determine the resistance for that pipe length and flow rate, and first determine whether the 18" pipe has that capacity, and then find a pump which will produce that flow at that head pressure.

12-05-2008, 04:35 AM
Do we get the job if we supply you the information you want...

12-09-2008, 01:49 AM
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 thanks for all the reply, i really appreciated. Nice forum here.

12-09-2008, 01:54 AM
:) Hahahah, i cant give you the job because it located far east of Indonesia. And im not sure if im capable for this project if i dont have the answer yet. :)

master plumber mark
12-09-2008, 02:05 AM
That is not really in the feild of the average plumber....

You should go try some other site that has a lot of
numbers crunchers, and mechanical enjeneers that would
love to debate something like this..

Of course if you come to a service DIY plumbers forum to ask a question like this ,
then it is obvious that it is out of your capabilities also..

you just dont know it yet...

If no one has got any real specs or plans already drawn up for the project for you to bid on....
it either means that you must be doing "missionary work"
in some backward hell hole somewehre,

or the people doing this job dont have a
clue what they are doing or dont have any money......

unless you are a glutton for punishment

I suggest you bid this job, bid it extremely high..

and dont expect to ever get paid........

12-09-2008, 08:26 PM
Look for an engineering forum, those guys will love this.

Gary Slusser
12-09-2008, 08:51 PM
IMO you will probably have to use more than one pump.

Where to put the others I don't know. Before you ask someone that can tell you, you have to know the elevation and friction loss of the pipe material. And then you probably will not be using PVC in less than 40' or longer sections with bell ends to reduce friction loss.