This document specifies general requirements for design, testing and performance, and describes the test methods that apply to portable, transportable and fixed equipment for the measurement of the oxygen concentration in gas mixtures indicating up to 25 % (v/v). The equipment, or parts thereof, may be intended for use in explosive atmospheres (see 4.1) and in mines susceptible to firedamp.This document applies to equipment intended for monitoring oxygen deficiency and enrichment.EXAMPLEMonitoring oxygen deficiency and/or enrichment includes:-protection of human health and safety in potentially oxygen deficient atmospheres;-fire protection by monitoring areas with reduced oxygen concentration;-fire protection by monitoring oxygen concentrations exceeding that of normal ambient air.This document also applies to equipment with an oxygen measuring function for explosion protection in the case of monitoring inertisation.NOTE 1Inertisation is an explosion protection technique where a potentially explosive atmosphere is purged with inert gas.NOTE 2Commonly used oxygen sensors in commercial equipment for industrial application are:-electrochemical sensors (aqueous and solid electrolytes);-paramagnetic sensors;-zirconium dioxide sensors;-tunable diode laser absorption spectroscopy sensors (TDLAS).This document is applicable to equipment intended to measure reliably the oxygen concentration, to provide an indication, alarm or other output function, the purpose of which is to give a warning of a potential hazard and, in some cases, to initiate automatic or manual protective action(s), whenever the level exceeds or falls below an alarm set point.This document is applicable to equipment, including integral sampling systems of aspirated equipment, intended to be used for commercial, industrial and non-residential safety applications.This document does not apply to external sampling systems, or to equipment of laboratory or scientific type, or to medical equipment, or to equipment used only for process monitoring and/or control purposes. For equipment used for sensing the presence of multiple gases, this document applies only to the measurement of oxygen.This document is also applicable to equipment using optical principles (e.g. TDLAS), where the optical transmitter and receiver or the optical transceiver (i.e. combined transmitter and receiver) and a suitable reflector are not located in a common enclosure. However, in this case it will be necessary to modify the test conditions described in Clause 5.3 and to introduce supplementary tests to Clause 5.4 of this document. Such supplementary tests will include alignment, beam block fault, long range operation. Guidance to appropriate modification of the test conditions and supplementary tests can be taken from EN 60079 29 4. Modifications of the test conditions as well as modified and supplementary tests are expected to be agreed between the manufacturer and test laboratory and identified and described in the test report.