How To Size A Pump For Irrigation

Pump sizing is essential when choosing the correct pump for an irrigation application. Incorrect sizing tin lead to low pumping efficiency and may negatively touch free energy consumption and toll, or may result in the irrigation organization not performing at all. The post-obit simple steps will help you quickly notice the performance required for the application and so that you can select a pump that is all-time suited for the job.

Step One – Gallons Per Minute (GPM)

The first step in sizing a pump for irrigation is to determine the total Gallons Per Minute (GPM) required. To practise this, you will need to know how many sprinkler heads will be utilized in the largest sprinkler zone. Each sprinkler caput requires a specific GPM (this number can be found in the specifications for the sprinkler heads). One time you know the GPM each sprinkler head requires, multiply that number by the amount of sprinkler heads that are present in this zone. The product of these two numbers will requite you the full GPM.

Step Two – Total Dynamic Head (TDH)

The second step in sizing a pump is to make up one's mind the Total Dynamic Head (TDH). The TDH is a calculation of the required force per unit area (PSI) for the irrigation system to operate efficiently and boosted or lesser required pressures that the pump must perform to accommodate for the system set up. There are 3 factors in the system set upward that tin affect the amount of pressure the pump must produce – elevation change, suction lift or incoming pressure and friction loses.

Elevation modify is determined by measuring the height change from the pump outlet to the highest indicate in the sprinkler system. This is the elevation that the pump has to push button the water upward.

Suction lift or incoming pressure relate to the intake side of the pump. Is the pump boosting the pressure of city water? That's incoming force per unit area and the corporeality of incoming pressure would be subtracted from the total pressure required because that force per unit area already exists and then the pump does non demand to create information technology. Suction lift is the distance in top between the water level and the pump inlet. The pump needs to pull the water up from the water level.

Friction loss is created when the water moves through the pipework in the irrigation system. These losses are easily adamant by using a Friction Loss Chart. On the Friction Loss Chart, find the desired GPM (from pace one) at a velocity of five' per second (+1/-ane), to find the most efficient pipe size for the arrangement (if the pipe is already in identify and will not exist changed, you'll need to look at the existing pipe size regardless of the efficiency). Place the head loss anxiety for the type of piping your system is using (most irrigation systems use PVC pipe). Multiply this number by the number of 100' lengths in the largest pipage run (for example, if there is 300', you would multiply by 3). Please note that valves, strainers, and fittings will contribute to losses. In this case, refer to manufacturer's loss data and include in Friction Loss total.

Pounds per square inch (PSI) is the terminal part of the TDH equation and refers to the pressure required at the end of the line of the largest zone. To calculate PSI, utilize the instructions that come up with your sprinkler heads. This number should be multiplied past 2.31, to give you lot the total PSI in feet, considering all of the other variables in your equation are expressed in anxiety.

The Total Dynamic Caput (in feet) will be calculated as:

PSI + Elevation modify + Suction lift – pressure boost + friction loss = TDH

Step Three – Power and Water Supply

The terminal application aspects to consider when choosing a pump are the power and h2o supplies. Whether the pump will be electrical or gas driven and what power rating you volition need volition commonly be based on what power source is bachelor on site. If the h2o sources are muddied, filtration may exist required (filters volition bear upon your TDH due to friction losses).

Footstep 4 – Using a Pump Curve

You at present have the performance requirements for the application, which you lot will use to select a pump that will provide the required performance. A pump bend is set upwards with an X and Y axis – discover your performance requirement on the axes to identify the pump that provides the required performance. If you find that the results are between two pumps, it is better to size up than to size downwards. Don't forget to select a pump that uses the available power source and rating.

Our pump data worksheets tin actually help to walk y'all through this procedure and provide a record of the information you gathered. If you have any trouble working through this process, please contact our pump experts for assist.