Constant Speed on an Irrigation Pump
This is holding the irrigation engine at the speed that gives the desired flow. With a hand-set throttle lever this speed comes out slightly different at every start-up; when a stored work speed is used, the same point is repeated. Water pump and irrigation pump are directly among the declared application areas of the GS740.
In irrigation, flow determines the working pressure of the system's drip or sprinkler heads. If the speed is low the heads do not open fully and distribution deteriorates; if the speed is high, fuel is burned needlessly and the pump and the line are strained further. Once the correct speed is found and stored, every irrigation session runs under the same conditions.
On the GS740 this is done by pressing the button for 3 seconds to store the speed found with the potentiometer. After that a short press toggles between idle and that speed; it becomes easy to drop the engine to idle while opening or closing the line.
One distinction has to be maintained. What is stored and held is the position of the throttle lever. When the water level in the well drops or the line resistance changes, the load on the engine changes and at the same position the actual speed shifts somewhat. Holding the speed constant independently of load requires the GS740's optional active-feedback speed-holding module.
Context in which this term is used: Speed control of three pumps in drilling