Any well-built hydraulic power unit (HPU) includes a system pressure gauge on the high pressure side. When this HPU gets paired with a hydraulically driven submersible pump, the readings on that gauge can both help the operator reach the best operating point (given current conditions) and assist in analyzing a problem situation when the submersible pump is not moving water.
Finding the Best Operating Point:
In many parts of life, more is better, but when it comes to operating an engine based hydraulic power unit, that is not the case. By using the pressure reading it is easy to find the sweet spot for any particular pumping situation. Specifically, the pressure shown on the gauge is an indication of the amount of work being done by the hydraulic motor on the pump head. The higher the pressure, the harder the motor is working. This working pressure profile can vary for different styles of pumps, but the one thing that is the same across the board is this…when adjusting engine rpm the operator will see system pressure rising and until it stops. When the needle stops moving, it means that given the current set up, the system is at its most efficient point. Attempting to increase engine speed in an effort to get more submersible pump flow will only result in burning more fuel; it will not change the gpm output of the head. Of course, as conditions change, that ideal point will change too, so further adjustments will be required to stay at the best spot. By educating your customers and staff about this pressure point, it becomes a win, win, as fuel costs can be cut, wear and tear on engines is reduced and the environmental impact of the fuel burn is minimized.