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: paramagnetic sensors; electrochemical sensors (aqueous and solid electrolytes); tunable diode laser absorption spectroscopy sensors (TDLAS). This standard is also applicable when an apparatus manufacturer makes any claims regarding any special features of construction or superior performance that exceed the minimum requirements of this standard. All such claims shall be verified and the test procedures shall be extended or supplemented, where necessary, to verify the claimed performance. The additional tests shall be agreed between the manufacturer and test laboratory and identified and described in the test report. This European Standard is applicable to oxygen alarm apparatus 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 a preselected alarm concentration. This standard is applicable to apparatus, including integral sampling systems of aspirated apparatus, intended to be used for commercial, industrial and non-residential safety applications. This standard does not apply to external sampling systems, or to apparatus of laboratory or scientific type, or to medical equipment, or to apparatus used only for process control purposes. For apparatus used for sensing the presence of multiple gases, this standard applies only to the measurement of oxygen. This standard is also applicable to apparatus 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 and to introduce supplementary tests to Clause 6 of this standard. Such supplementary tests will include alignment, beam block fault, long range operation. Guidance to appropriate modification of the test conditions and supplementary tests may be taken from EN 60079-29-4. Modifications of the test conditions as well as modified and supplementary tests shall be agreed between the manufacturer and test laboratory and identified and described in the test report.