The measurement of the pumping rate of the various styles of oilfield pumps is done by pump rate sensors. Pump rate sensor are also sometimes called stroke counters. Pump rate sensors can be mechanical switches, inductive proximity sensors, or magnetic pickups. However they all work by sensing the movement of a flange bolt, piston, or sprocket attached to the pump. For positive displacement pumps each rotation of the power end shaft or each stroke of the piston corresponds to a specific volume of fluid pumped.
Mechanical stroke counters usually have a switch with a long steel whisker that is triggered on every stroke of the pump. Magnetic pickups sense the change in the amount of steel (or other ferro-magnetic metal) in front of their face and create an output signal that corresponds to the change. The change in amount of steel in range of the sensor can be in the form of a bolt head or sprocket tooth. Proximity switches also work on a similar principal except that they generally output a binary ON or OFF signal. Rate sensor electrical signals can be fed directly in to the Rapidlogger system and recorded, totalized and displayed.
