Tag
#measurement
3 topics across all disciplines.
Measuring temperature and pressure — thermowells, thermocouples and gauges
Why a thermocouple needs matching extension wire and cold junction compensation, why an RTD should never be wired with two wires, what a thermowell costs you in response time, and why a pressure gauge needs a siphon on steam and a snubber on a reciprocating pump.
Measuring flow — orifice plates and the alternatives
Why most flow measurement is really a pressure measurement, what the square root relationship means for turndown, why straight lengths are a measurement requirement rather than a layout preference, and how to choose between orifice, vortex, magnetic, Coriolis and ultrasonic meters.
Measuring level — why most level readings are really weight
How differential pressure, displacers and radar each infer level, why a wet leg that partially drains makes the tank read full, what a bridle is for and how it lies on hot service, and why a gauge glass disagreeing with the transmitter is information rather than a nuisance.