How to calculate pump design

to calculate total head need to know

discharge pipe diameter and pipe material .

are pipe end opened to atmosphere at the same horizontal level for pump?

are your pump sucks water from surface water, overhead tank or deep well?

300mtr long? that is not long but head. 30 m3/hr is flow and head is 300 metre. convertinto feet and it becomes head in feet.

you already have your flow rate, through that you can determine your pipe size..get your friction loss (nomograpgh) and multiply it to your 300m length of pipe.. determine how much residual pressure you need at the end of your pipe.

residual pressure + friction loss = head of your pump...

an 1234...there is quite a bit data missing from question including the change in height or vertical distance your planning to pump......

Start with Mass conservation to develop velocities

Then used Bernoulli with system losses

Thus should give all the missing data

Total head = change in elevation + friction losses

Then from pump manufacture tables you can select a pump at a specific RPM & horsepower

If you need worked examples our contact details are at http://www.alnoproductservices.com.au

Anthony

an1234 -- Pretty obvious to me that you're new at designing an application for pumping.

First off you are going to need to know just what head the pump will need to produce to pump the 30m3/hr. The head really has two parts. First it is the amount of head in meters to overcome friction losses in the pipeline. Second is the head in meters needed to lift the flow to a higher level. This is measured from the surface of the liquid in the suction tank to the outlet at the end of the discharge pipe.

The first head will depend on the length and inside diameter of the pipe and 300 meter known length. You add to this the head in meters. (or subtract it if the discharge height is lower than the suction) Note: There are some second order factors here like suction line conditions, type and condition of pipe, pipe fittings etc. But let's not complicate the problem at this point.

The total of the two heads is the head the pump will have to produce. But wait! Something is still missing. We don't know the diameter of the pipe; so how can we calculate the friction head loss?

You need to pick the size of the pipe. This is usually based on economic considerations. Larger diameter pipe has lower friction loss but costs more to buy and install. Lower friction loss means less power used. Note here that head is energy per unit mass. Flow is mass per unit time. The product of the two is energy per unit time since the mass terms cancel out. (You metric system guys go figure out the right constants. I'm an old school English system guy and don't have the conversions in the front of my brain.)

So what does the engineer do? Calculate the friction loss and the cost of several different alternative pipe diameters including the total cost of the extra power needed for smaller diameters for a period that your organization likely uses to determine the payback for its capital investments or routine expenses as the case may be for your project.

Let's say the possible pipe diameters for this 30m3/hour (approx 130 gpm) application are 50mm, 65mm and 80mm. Calculate the friction head and the total head loss for all 3 possibilities and convert to KWh. Also calculate your cost for the pipeline for each size for future reference.

Now go to at least one of your possible pump suppliers with three applications for which you request preliminary pump selections and price quotations. Ask for in addition to price quotations the vendor supply a curve of head vs. capacity, power versus capacity and pump efficiency vs. capacity for each of the three selections. It is perfectly reasonable to tell the pump supplier that this is a preliminary selection that you will use to complete the design of the piping system that is the best economic fit for the application.

Note that a competent pump company or sales representative for them should be able to provide some advice and help for your final calculations and brief you on some of the finer points of pump selection I haven't mentioned so that the selection you ask for a final quotation on will be the right one for the job.

Ed Weldon

well explained Ed..GA for you