Differential Pressure

Differential pressure (DP, Diff, Delta P) is the difference in pressure between two separate points. It, in general, is a measure of pressure where the reading and reference values are variable. Differential pressure is calculated by subtracting one of these values from the other. If Pipe A flows at 100 psi and Pipe B flows at 30 psi, the differential pressure would be 70 psi.

A differential pressure can be measured between two points on independent systems or between two different points on the same system.

One application of differential pressure is to monitor flow and filtration in industrial systems. Differential pressure is used to determine if a pipeline has any clogs or contaminates as particles flow through orifices and filters. If part of the pipe gets clogged, it will cause a change in the pressure, which causes differential pressure to increase or decrease.

A more widely appreciated application of differential pressure involves the pressurization of airplane cabins. Most modern day people have ridden in an airplane sometime in their life. You take off and almost immediately your ears start to pop due to the change in pressure as you ascend into the sky. This is a mild symptom of the extreme pressure change the plane is experiencing. By gauging the pressure outside and controlling the cabin pressure accordingly, humans are able to travel comfortably at 35,000 feet without needing an oxygen mask or experiencing any negative health effects.