Solution:

Venturimeter : a device used for measuring the rate of flow of a fluid flowing through a pipe
Differential pressure transmitter : equipment will sense the difference in pressure between two ports and produce an output signal with reference to a calibrated pressure range
Potentiometer : device used to measure the internal resistance of a cell, to compare the e.m.f. of two cells and potential difference across a resistor
Manometer : scientific instrument used to measure gas pressures