Pump capacity

I would refine your answer by trying to simplify the affinity law you suggested. The actual formula is as follows:

BHP (break horsepower) = (Flow in GPM x Head in feet)/(3960)(hydraulic efficiency)

In the questioner's "problem" the 250cuM/hr relates to 1100 GPM and the 20KG/sq cm would relate to 656 feet of head. Using the above formula, the "ideal" BHP would be (1100 x 656)/3960 = 182.2 BHP without regard for the pump hydraulic efficiency. The 656 feet of head is rather high and can probably only be accomplished using a multi-stage pump, more commonly called a "turbine" pump. I am looking at one such pump that offers 1100 GPM @ 172 feet of head per stage or "bowl". The hydraulic efficiency of that particular pump bowl is about 72%. The required head of 656 feet would require four such bowls to accomplish. Therefore, the head available with the pump I have described would be 172 x 4 = 688 feet. Going back tho the formula above, we can now input the hydraulic efficiency of 72% found on the manufacturer's published curve, and find that the actual BHP at the design conditions would be 182.2/.72 = 253 BHP. The motor efficiency would probably be closer to 90%, and if a premium efficiency motor is used, it could be 95%. Using 90% motor efficiency, the "wire-to-water" efficiency would be 281 BHP. In summary, using a turbine pump with 4 stages and a 300 HP motor, the problem can be solved.

I apologize if it looked like I was hiding behind the Guest moniker. I forgot to sign in. Here, again, is my response:

I would refine your answer by trying to simplify the affinity law you suggested. The actual formula is as follows:

BHP (break horsepower) = (Flow in GPM x Head in feet)/(3960)(hydraulic efficiency)

In the questioner's "problem" the 250cuM/hr relates to 1100 GPM and the 20KG/sq cm would relate to 656 feet of head. Using the above formula, the "ideal" BHP would be (1100 x 656)/3960 = 182.2 BHP without regard for the pump hydraulic efficiency. The 656 feet of head is rather high and can probably only be accomplished using a multi-stage pump, more commonly called a "turbine" pump. I am looking at one such pump that offers 1100 GPM @ 172 feet of head per stage or "bowl". The hydraulic efficiency of that particular pump bowl is about 72%. The required head of 656 feet would require four such bowls to accomplish. Therefore, the head available with the pump I have described would be 172 x 4 = 688 feet. Going back tho the formula above, we can now input the hydraulic efficiency of 72% found on the manufacturer's published curve, and find that the actual BHP at the design conditions would be 182.2/.72 = 253 BHP. The motor efficiency would probably be closer to 90%, and if a premium efficiency motor is used, it could be 95%. Using 90% motor efficiency, the "wire-to-water" efficiency would be 281 BHP. In summary, using a turbine pump with 4 stages and a 300 HP motor, the problem can be solved.

Could you please explain what is that 3960?

Assuming you mean 20 Kg/cm2 -- that will be a Whacking Big Gear Pump/ MultiPiston Pump.

Ask Pipeline Oil Pump makers if they will offer with Stainless Steel Liners/rings for Water.

What pH?

Salty?

Dear Mr. Ajithkumard,

I will assume that you mean a pressure of 20 KG/square cm which is approx. equals to 20 bars.Also i will assume that the water temperature is the room temperature.

A multi-stage high pressure centrifugal pump is the appropriate type.

To calculate the motor power for such a pump you can use the following equation:

Power=fluid density*discharge*head/367*efficiency.

NB:the discharge is in cubic meters per hour, the head is in meters water,the density is in kg/cubic dm and the power is in KW.

Dependig upon the overall efficiency of the unit(pupm+motor) you can calculate the requested power.

If we assume efficiency=0.75,then motor power will be 181 KW

Sayed Sarhan