Differential pressure transmitters with an orifice are widely used as a reliable flowmeter in process industries. The most frequent problem with this type of flowmeter is blockage in impulse line: it causes a severe deterioration of measurement accuracy. Hence, this paper develops a new detection method of impulse line blockage with digital differential pressure transmitter in a steady-state steam line. This method, which utilizes inherent pressure fluctuations of the steam line, consists of two functions: (i) detecting impulse line blockage by evaluating standard deviations of differential pressure, and (ii) specifying which side of impulse line is blocked from the phase difference between two impulse lines.
