How Differential Pressure Flow Measurement Works
A differential pressure gauge connected to the inlet and outlet of a primary flow element, such as an orifice plate or venturi, represents a simple and cost effective method of monitoring flow. Connect the high pressure side to the inlet of the flow element and the low pressure side to the outlet, and the flow rate is easily read on a differential pressure gauge analog dial. Switches and transmitters allow for remote measurement of the differential pressure flow rate.
Bernoulli’s law tells us that flow rate is proportional to the square root of differential pressure. This connection between pressure and flow is a simple calculation that enables the most popular and cost effective method of measuring flow in many applications. Imagine the high cost of an in-line flow meter on a 24-inch pipe. Compare that to the cost of installing a simple orifice plate, or any method of creating a slight pressure drop, or pressure increase, and you have a solution that can save hundreds of dollars.