Determining the Capacity of a Pump

Whether you are flood irrigating, flooding a duck pond, or just determining your pump capacity, it is good to know the measure of your pumping performance.  Below is a table of estimated performance for Crisafulli pumps.

Number of Acres Covered in Twelve Hours Pumping

To estimate the pumping capacity of any given unit, construct an L-shaped measuring instrument similar to the one shown in the sketch.  The shorter side should be 4" long.  The longer side may be any convenient length marked in inches.  With the water flowing from the horizontal open discharge, place the long side of the L along the top of the discharge pipe, allowing the shorter side to hang downward as shown in the drawing.  Slide the L along the pipe until the 4" length barely touches the flow of water.  Note the distance travelled ("X") by the flow of water before it drops 4".  Presume, for example, that the distance travelled is 15" and the inside diameter of the pipe is 3".  Consulting the table below, locate 15" in the fisrt column (Horizontal Distance X(inches()).  Then move horizontally to the column labeled 3 (pipe diameter used).  Thus, for our hypothetical unit the pumping capacity is approximately 183 gallons per minute.

First Column = Horizontal Distance X (inches)
First Row = Nominal Pipe Diameter (inches)
Last Column = Average Velocity

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