This Standard primarily applies to explosion-protected gas detection instruments used to measure the concentration of oxygen and toxic levels of gases and vapours or those parts of multi-gas detection instruments which are measuring such substances.It does not apply to those parts of multi-gas detection instruments used to detect flammable gases and vapours at levels related to their lower flammability limits (LFL) and above. Such parts of multi-gas instruments are covered by AS/NZS 61779.1.Instruments that are within the scope of this Standard and AS/NZS 61779.1 may be assessed and tested to either Standard.NOTE: Certain regulatory bodies require compliance to both.While it is the main intention of this Standard to be applied to explosion-protected equipment, this Standard may be used for other purposes.