How to Calculate Head Pressure for My Submersible Pump?

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Understanding Well Layout and Pump Specifications When calculating head pressure, it’s essential to understand your well’s layout, including the static water level (SWL) and the pump depth. Measure the SWL by lowering a weighted rope or wire into the well until it reaches the water surface. Record the depth from the well’s surface to the water level. Next, measure the depth from the well’s surface to the submersible pump’s position. This will give you the pump depth. You’ll also need to know your pump’s specifications, including its rated flow rate (Q) in gallons per minute (gpm) or liters per minute (L/min), and the corresponding head pressure (HP) in feet or meters.
Calculating Head Pressure To calculate the head pressure, you’ll need to determine the total dynamic head (TDH) in feet or meters. The TDH is the sum of the static water level, the pump depth, and any additional head losses due to friction, fittings, and valves. Use the following formula to calculate TDH: TDH = SWL + Pump Depth + Additional Head Losses. Convert the TDH to feet or meters, using 1 meter = 3.2808 feet. Now, use the pump’s rated flow rate and head pressure specifications to find the corresponding head pressure. You can use a pump curve or consult with the manufacturer’s technical documentation to find the correct data.
Example Calculation Let’s assume your well has a static water level of 40 feet, and the submersible pump is located at 80 feet. The total dynamic head (TDH) would be 40 feet (SWL) + 80 feet (Pump Depth) = 120 feet. If you have additional head losses of 10 feet due to friction and fittings, the new TDH would be 120 feet + 10 feet = 130 feet. Convert the TDH to meters: 130 feet x 0.3048 (meters per foot) = 39.62 meters. Now, use the pump curve to find the corresponding head pressure for a flow rate of 10 gpm (approximately 0.178 L/s).