I need to find a centrifugal Pump that will boost water though 3" poly pipe.?

Question

I run a small polypipe company and i need to find a pump that i can put in line that will boost the water so i can get more rate to a drilling rig. The line is 5 miles long and i have a 20 HP Pump with a 480 3 phase Generator. im getting almost 50 gallons a min. but i need between 80 and 90. Any suggestions.

Answer 1

"Obviously" you need increase the pressure at the pump to go from 50 to 90 gallons a minute which may exceed the capacity of the pipe.  

This chart

http://www.engineeringtoolbox.com/fricti...

shows that the pressure loss per hundred feet of pipe in 3" plastic pipe triples when going from 50 to 90 gallons per minute.

This calculator (which is linked from the previous page)

http://www.engineeringtoolbox.com/hazen-...

  Suggests you have about 85 psi on the water now and will have to go to just under 250 psi to get 26000 feet of 90 gpm flow.

  This table

http://www.engineeringtoolbox.com/pvc-cp...

says the maximum operating  pressure rating for 3" schedule 40 PVC pipe is 138 psi which fits my impression, so you will be going from well below the maximum to well above it to achieve the flow you want.

  Are you running the pipe 24 hours a day?  Can you tank water to accumulate at the drill site by running the pump longer?

Answer 2

You have neither the line size nor the pumping horsepower to increase the flow 70-80%. As Mike1942 mentioned, IF you can do the drilling intermittently, you can pump to storage using what you have. I suppose there are other ( high pressure ) booster  pumps at the expanded drill site.

Too bad the line is not a 4"; it would do the job quite nicely at about 60 psi loss. However, between the 16- 18% lower loss with a 4" line and the 70- 80% or more higher flow you would still need a  25-30  horsepower pump and power supply.

Sorry, but it looks like you are going to have to spend some money. Look at the other end and determine if modifications to the drilling requirements to reduce the water flow would be less costly in the long run. Consider each of the optional installation costs of  added  pipe, or of a storage tank or of alterations to the drill rigs. Consider also the increased operating cost of more power.

The other factor is time needed to modify the system by each of the options.

Finally, you are going to have to do something drastic, because the increase in flow is drastic, however, look at the pump again in consideration of service with a new 4" pipe or in how much you can push the 3".  The manufacturer's performance data curve will show the performance of that size pump casing with the several sizes of impeller. A change in impeller diameter might get you by with that particular pump frame with increased flow, if you are lucky. The curve will show the brakehorsepower needed to drive the pump. Also, look at the actual motor amps compared to the motor full-load amps on the nameplate. The nominal 20 horsepower motor may not be fully loaded. My comparisons , above, have been assuming that it was.

Here is the general pumping equation for water

BHP= GPM (TDH) (S.G.) / 39.6 (%efficiency)

TDH is pressure rise expressed in ft of water.

2.31 ft of water = 1 psi

S.G. is specific gravity and is 1.0, so leave it out unless it is not pure, cold water.

Give Mike1942 the points; he answered first with sound data and a good idea.

Answer 3

U need to keep your eye on the head pressure. If it gets too high the pipe will blow.