A pump is a device that moves fluids by physical or mechanical action. The two general categories of pumps are rotodynamic and positive displacement. Rotodynamic pumps work by increasing the flow velocity and converting kinetic energy into potential energy (pressure). Positive displacement pumps move fluid by trapping a fixed amount and forcing that trapped volume into the discharge pipe. Rotodynamic pumps represent the vast majority of total pump energy use.
In February 2013, DOE initiated a rulemaking for pumps with the publication of a framework document. The Appliance Standards and Rulemaking Federal Advisory Committee (ASRAC) subsequently formed a working group of relevant stakeholders to negotiate consensus standards. In January, 2016, DOE published the first-ever standards for pumps based on the recommendations from the working group. The standards take effect in 2020. Clean water pumps are used for a variety of applications including commercial building HVAC systems, pressure boosting, irrigation, and municipal water and wastewater.
The principal way to improve pump efficiency is to hydraulically redesign the pump to reduce losses. Beyond improvements to the efficiency of bare pumps, large energy savings can be achieved through the use of variable-speed drives in variable-load applications. In variable-load applications, the change in load is typically met by throttling the pump using valves. This control approach leads to significant energy waste. In contrast, the use of a variable-speed drive allows for reducing the speed of the pump to match the load. Reducing the speed of the pump can yield significant energy savings since power decreases with the cube of the speed.