Interview Question

Instrument & Control Technician Interview



if you have a pump in a run of piping a dp pressure readouts coming off the piping, one 3 floors above, one in line with the pump, and one 3 levels below, which is most accurate? Will the one above read higher, lower, or the same? What about the one below?

Tags:detectors, pumps, fluid flow
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2 Answers


you have to understand and apply Bernoulli in the context of reading flow. what are you reading? static pressure? velocity pressure? the readings can be accurate at any point, but you have to adjust using textbook formulas for the changes that occur in flow both downstream and upstream of the pipe. for example, you have to either add or subtract friction loss and head loss depending on where the reading is. If you calibrate readings for such changes, then you can get accurate readings in any location.

Anonymous on


most accurate: the one in line one above: lower because you are using the pump head to get the water to the detector and gravity is working against you. one below: higher because the weight of the water on top of the detector.

Anonymous on

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