This European Standard specifies general requirements for construction, testing and performance, and describes the test methods that apply to portable, transportable and fixed apparatus for the measurement of the oxygen concentration in gas mixtures indicating up to 25 % (v/v). The apparatus, or parts thereof, may be intended for use in potentially explosive atmospheres (see 4.1) and in mines susceptible to firedamp.In the case of inert gas purging (inertization), it applies also to apparatus with an oxygen measuring function for explosion protection.NOTE Commonly used oxygen sensors in commercial equipment for industrial application are:a) paramagnetic sen