It is used to measure the pressure of gas lines and the input pressure to the chlorinator. It is completely resistant to the corrosiveness of chlorine gas.

Pressure gauges, which are devices that measure the internal pressure of media within a system, are among the most often used instruments in any given industrial facility.

Gauge has become the most common word to describe a measuring device or a gauge pressure sensor measuring relative to ambient pressure.
pressure gauge, instrument for measuring the condition of a fluid (liquid or gas) that is specified by the force that the fluid would exert, when at rest, on a unit area, such as pounds per square inch or newtons per square centimetre.
Gauge pressure, also called overpressure, is the pressure of a system above atmospheric pressure. Gauge pressure is zero-referenced against ambient air (or atmospheric) pressure, so gauge pressure readings include the pressure from the weight of the atmosphere.
Pressure gauges are used to measure the pressure of liquids, vapors, solids, and gases. It is used for the inspection of air brakes on trucks. Pressure gauges are used in chemical, petrochemical, sanitary, pharmaceutical, and process industries.