how to find the capacity ( discharge flow) of the centrifugal pump.?

Question

we have a pump connected to diesel engine. there is no name plate only data available is suction dia( 6 inch) , discharge dia( 4 inch),
discharge pressure( 150 psi), fluid( water), rpm ( 1620 rpm). with this datas how can i find how much flow the pump is discharging.

Answer 1

usr Bernoulies principle and calculate the discharge velocity assuming suction head contribution is zero.
Mulyiply discharge velocity and discharge area to get discharge volumetric rate!
eg:
Discharge Pressure/density of water gives the Pressure head the pump will develop in feet >(pounds/sq foot) /( lbs/ cu. feet) = (feet )< ie 150 x 144 / 62.4 = 346.15 feet

Equate this to the Velocity Head ( Velocity squared/2x g)
solve for velocity , which would be ( sq. root of 346.15x2x32.4) = 149 ft/sec.

discharge dia. is 0.25ft and discharge area is 0.049 sq ft.

discharge velocityx dischare area is (149x0.049) is 7.3 cft/sec or 26280 cft per hr.

Answer 2

Centrifugal Pump Capacity Calculation

Answer 3

I don't think the nameplate data is going to do you much good. Perhaps you could get your friendly fire department to bring over a pitot gage and measure the pressure at an orifice of a known diameter. Reading the pressure at no flow, and the pressure at flow gives you two points on a curve, from which you can calculate the flow at any pressure.

If this is not a fire pump, you could find that you could reduce the engine speed and still satisfy your pumping needs.

Answer 4

It would help if you had at least a generic pump curve for this question. If you have the manufacturer, you may be able to ask for one by e-mail or they may even have one on their web site. You also do need to have the pressure your 175 gpm is rated for to calculate this, so yes, you do need to consider the system head. You also need to consider one pump vs. two pump operation. One pump may run out the pump, giving you lots more flow than 175 gpm but low head. eventually tripping your motor on high current, especially since you are going from a 400 psi source to atmospheric pressure. Two pumps will increase your flow but also your head, reducing the chances of runout.

Answer 5

You can piss around with the equations and try to come up with a flow rate, or you can just slap a flow meter on the discharge and measure it. Much simpler.