Explosive atmospheres - Part 29-1: Gas detectors - Performance requirements of detectors for flammable gases

This part of IEC 60079-29 specifies general requirements for construction, testing and performance, and describes the test methods that apply to portable, transportable and fixed equipment for the detection and measurement of flammable gas or vapour concentrations with air. The equipment, or parts thereof, is intended for use in explosive atmospheres and in mines susceptible to firedamp.

This part of IEC 60079-29 is applicable to flammable gas detection equipment with a measuring range up to any volume fraction as declared by the manufacturer, and which is intended to provide an indication, alarm or other output function; the purpose of which is to indicate a potential explosion hazard and in some cases, to initiate automatic or manual protective action(s).

For the purposes of this part of IEC 60079-29, the term indicating up to a volume fraction of X % or X %LFL includes equipment with an upper limit of the measuring range equal to or less than X % or X %LFL.

This part of IEC 60079-29 is applicable to equipment, including the integral sampling systems of aspirated equipment, intended to be used for commercial, industrial and non-residential safety applications.

This part of IEC 60079-29 does not apply to external sampling systems, or to equipment of laboratory or scientific type, or to equipment used only for process monitoring and/or control purposes. It also does not apply to open path (line of sight) detectors which are within the scope of IEC 60079-29-4. Only equipment with very short optical paths intended for use where the concentration is uniform over the optical path are within the scope of this standard.

For equipment used for sensing the presence of multiple gases, this part of IEC 60079-29 applies only to the detection of flammable gas or vapour.

This part of IEC 60079-29 supplements and modifies the general requirements of IEC 60079-0. Where a requirement of this standard conflicts with a requirement of IEC 60079-0, the requirement of IEC 60079-29-1 takes precedence.

NOTE 1 IEC 60079-29-1 is intended to provide for the supply of equipment giving a level of safety and performance suitable for general purpose applications. However, for specific applications, a prospective purchaser (or an appropriate authority) can additionally require the equipment to be submitted to particular tests or approval. For example, Group I equipment (i.e. equipment to be used in mines susceptible to firedamp) might not be permitted to be used without the additional, prior approval of the relevant authority in mines under its jurisdiction. Such particular tests/approval are to be regarded as additional to and separate from the provisions of the standards referred to above and do not preclude certification to or compliance with these standards.

NOTE 2 All equipment calibrated on specific gases or vapours can not be expected to correctly indicate on other gases or vapours.

For the purposes of this standard, the terms lower flammable limit (LFL) and lower explosive limit (LEL) are deemed to be synonymous, and likewise the terms upper flammable limit (UFL) and upper explosive limit (UEL) are deemed to be synonymous. For ease of reference, the two abbreviations LFL and UFL may be used hereinafter to denote these two sets of terms. It should be recognized that particular authorities having jurisdiction may have overriding requirements that dictate the use of one of these sets of terms and not the other.

NOTE 3 Indication of concentration in %(v/v) or vol ppm can also be available for equipment which measures up to 100 %LFL or 20 %LFL. In that case, units of measurement might need to be selected in agreement with the manufacturer when verifying the performance requirements of Annex A.