Voices: Rezabek

Digital signals support low-maintenance approach to differential pressure measurement

Digital precision and stability allow accurate DP level and flow readings using two pressure transmitters.

By John Rezabek, process control specialist, ISP Corp.
Feb 2, 2016

A differential pressure (DP) application had capillaries—small-bore armored tubing connecting the remote seal to the transmitter—in excess of 50 feet. When the weather turned cold, there was enough of a viscosity change in the fill fluid to cause a time lag in the longer leg, making an otherwise quiescent measurement extremely noisy. If this had been "real" DP instability, it could have meant death and destruction for the millions of dollars of precious metal catalyst in the reactor, so it caused more than a little trepidation—until we figured out the correlation with cold weather.

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