Determination of delivery pressure from pump

[kunalvanjare]

We want to know how can we determine the pressure of the liquid at the delivery end of the pump. We have a centrifugal pump and a 2" pipeline at the delivery end. Pump delivery performance as per catalog is 510LPM @20 mtr head to 348LPM @36mtr head.

The delivery pipe is connected to a manifold on which spray nozzles are connected around 70 Nos.
The total length of pipe from the pump outlet to the spray manifold will be approx 5 metres of which 1.5mtr is vertical & remaining horizontal.

We have mounted a pressure gauge on the line which gives a constant reading of 0.6-0.8 Kg/cm2 which is lower is lower than our expectations from a 5HP pump.

When we block the line just before the manifold, the gauge shows a reading of 3.5-4 kg/cm2.

Kindly help us determine the process of finding out the pressure in the line.

Also, If I have to select a pump that constantly delivers liquid at 3 Kg/Cm2, how do I go about the selection?

 

[jrmichler]

We need a system diagram that shows length and diameter of the piping, and elevations of the pressure gauge and the free surface of whatever you are pumping from. Also, what is the liquid? If not water, we need specific gravity and viscosity. If water, what is the temperature? What is the make and model number of the spray nozzles, or their rated pressure vs flow rate.

 

[kunalvanjare]

We need a system diagram that shows length and diameter of the piping, and elevations of the pressure gauge and the free surface of whatever you are pumping from. Also, what is the liquid? If not water, we need specific gravity and viscosity. If water, what is the temperature? What is the make and model number of the spray nozzles, or their rated pressure vs flow rate.

Thanks for the reply. I have enclosed a schematic of the process with relevant dimensions.

In brief,
Diameter of the pipe - 50mm or 2"
Elevation of pressure gauge from ground - 1700mm
Length of pipe - mentioned in diagram

Liquid - Water
Temperature - 60-70 degree Celsius
Nozzle Rated pressure - 2 Bar @ 10 LPM
Total no. of nozzles - Approx 80

The pump characteristics are also enclosed in an image. The one marked in red is the pump I am using.

Thanks.

 

[jrmichler]

Some quick calculations: 80 nozzles X 10 LPM = 800 LPM at 2 bar = about 2 kg/cm^2.

You can take it from here with the following suggestions:
1) Plot the pump curve (hand sketch is good enough) with flow on the horizontal axis and TDH (head) on the vertical axis.
2) Nozzle flow is proportional to the square root of the pressure. Plot the nozzle flow curve on the pump curve.

 

[JBA]

What is the pump's maximum delivery rate regardless of head?

 

[jrmichler]

Your question, and several other questions that you have not yet thought of, will be answered when you draw the pump curve, and add the nozzle flow curve to it. Post the curves here if you still have questions.