Orifice Flow Meter : A flow meter in which use is made of the loss of head at a point in a pipe, the bore having been reduced by the insertion of a plate in which a sharp edged orifice has been bored
H. J. Porter (Chairman - Technical Committee), Dictionary of Fire Technology, The Institution of Fire Engineers, The Victory Press (Leicester) Ltd. 1979 UK. (Fr Tech - Brit) {81}