Orifice Plate - An orifice plate helps measures flow through the differences in pressure from the upstream side to the downstream side of a partially obstructed pipe. The plate offers a precisely measured obstruction that narrows the pipe and forces the flowing substance to constrict. A DP cell allows the comparison of the pressure on the upstream (unobstructed) side and the downstream (constricted) side.

The greater the flow, the greater the difference in pressure as the substance maintains its constricted state for a longer distance, passing the downstream element. Different kinds of orifice plates include concentric, eccentric, and segmental, each of which has different shapes and placements for measuring different processes. Orifice plates are in common use in many installations.