Determine the Total Dynamic Head (TDH): The TDH represents the total resistance or head against which the pump must work to lift water to the desired height. In this case, you have a vertical lift of 20 feet. However, you should also consider other factors that add to the TDH, such as friction losses in the pipes, bends, and valves. You may need to consult with a hydraulic engineer or refer to the pump manufacturer's data for specific calculations.
Select a Pump Size: Once you have calculated or estimated the TDH, you can select a pump that can handle that head. Pump manufacturers provide performance curves and specifications for their pumps that indicate how they perform at different head heights (in feet or meters) and flow rates (in gallons per minute or liters per second).
Consider Flow Rate: Determine the desired flow rate or water delivery rate you need. The pump you choose should not only lift water to the desired height but also deliver the required flow rate. Match the TDH and flow rate with the pump's performance curve to find a suitable pump size.
Efficiency: Consider the efficiency of the pump. Efficient pumps consume less power to achieve the desired flow and head, which can result in energy savings over time.
Safety Factor: It's a good practice to add a safety factor to your calculations. This means selecting a pump that can handle a slightly higher TDH and flow rate than your minimum requirements to ensure reliable and consistent performance.
Type of Pump: The type of pump you choose (e.g., centrifugal, submersible, jet) will depend on your specific application and requirements.
Local Codes and Regulations: Be sure to check if there are any local codes or regulations that specify pump requirements for your application.
Keep in mind that pump selection can become more complex for large-scale or commercial applications, and it may require the assistance of a hydraulic engineer or pump specialist to ensure the correct pump size and configuration.
In summary, the size of the pump you need to lift water 20 feet depends on the total dynamic head (TDH), desired flow rate, efficiency, and other factors specific to your application. Careful calculations and consideration of these factors will help you select the appropriate pump size for your needs.
