This part of EN 60079-29 specifies performance requirements of equipment for the detection
and measuring of flammable gases or vapours in ambient air by measuring the spectral
absorption by the gases or vapours over extended optical paths, ranging typically from one
metre to a few kilometres.
Such equipment measures the integral concentration of the absorbing gas over the optical
path in units such as LFL metre for flammable gases.
NOTE 1 Actual values of concentration can be deduced only where it can be established that the concentration is
uniform over the optical path, for example in very short optical paths (＜100 mm). In such cases, the equipment is
within the scope of EN 60079-29-1 .
NOTE 2 This standard is based upon present absorption techniques using infrared radiation. Other techniques
and applications may require additional test considerations (e.g. pressure test).
Equipment falling within the scope of this standard is classified by the following types:
Type 1: an optical transmitter and receiver, located at either end of a path through the
atmosphere to be monitored.
Type 2: an optical transceiver (i.e. combined transmitter and receiver) and a suitable
reflector, which may be a topographic feature or a retroreflector, located at either end of a
path through the atmosphere to be monitored.
This standard is also applicable when an equipment 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 should be extended or supplemented, where necessary, to verify the claimed
performance. The additional tests shall be agreed between the manufacturer and the test
laboratory and identified and described in the test report.
This standard does not apply to any of following:
a) equipment intended to provide range resolution of gas concentration (e.g. Light direction
and ranging (LIDAR));
b) equipment consisting of a passive optical receiver without a dedicated optical source;
c) equipment intended to measure the local volumetric concentration of gas (point sensors);
d) equipment intended for the detection of dusts or mists in air;
e) equipment for cross stack monitoring;
f) equipment intended for the detection of explosives; and
g) equipment intended only for the identification of individual gas or vapour components,
(e.g. Fourier transform infrared spectroscopy (FTIR)).
This standard is applicable to equipment which is intended for use in hazardous or nonhazardous
areas, or both. Equipment for use in hazardous areas is also required to have
explosion protection (see 4.1.1).
This standard applies to portable, transportable and fixed equipment intended for commercial
and industrial applications.