scope:

This standard is concerned with the details of construction, performance and testing of portable, mobile and stationary electrical instruments that sense the presence of combustible gas or vapor concentrations in air. This standard considers the suitability of the instruments or parts thereof for use in Class I, hazardous (classified) locations as defined by the National Electrical Code® (ANSI/NFPA 70).

NOTE: IT IS STRESSED THAT ALTHOUGH COMBUSTIBLE GAS DETECTORS WARN OF COMBUSTIBLE ATMOSPHERES THAT MAY LEAD TO AN EXPLOSION, THEY DO NOT NECESSARILY WARN OF TOXIC GAS RELEASES. IT IS ALSO STRESSED THAT FINAL AND LONG-TERM EFFECTIVENESS OF ANY COMBUSTIBLE GAS DETECTION EQUIPMENT DEPENDS HEAVILY UPON THE USER, WHO MUST BE RESPONSIBLE FOR ITS PROPER APPLICATION, INSTALLATION, USE, AND REGULAR MAINTENANCE.

This standard contains requirements for combustible gas detectors of the fixed, portable and transportable types.

This standard applies to line-voltage operated instruments rated at 250V nominal or less, and to portable, mobile, or stationary-type instruments supplied by battery of a non-rechargeable (primary) type or a rechargeable (secondary) type.

For intrinsically safe instruments, this standard applies only to systems which utilize defined associated intrinsically safe apparatus (protective barrier assemblies). ''Entity'' concept does not apply to the performance Approval of combustible gas detectors.

This standard addresses combustible gas detection instruments intended to provide an indication or alarm, the purpose of which is to give warning of potential hazard.

This standard does not address gas detection instruments of the laboratory or scientific type used for analysis or measurement, instruments used for process control and process monitoring purposes, open path (line of sight) area monitors, or instruments used for residential purposes.

This standard is written for gas detection instruments that are intended to detect gas concentrations in air in the range from zero up to the lower flammable limit (LFL), since this is the most commonly used range for instruments intended to measure or monitor the degree of explosion hazard. This does not preclude instruments intended for higher concentration ranges, such as those intended to warn of a drop in concentration from a high value down to the upper flammable limit (UFL).

For instruments used for sensing the presence of oxygen, non-flammable toxic gases, and flammable gases or vapor concentrations in air, this standard applies only to the portion of the instrument sensing the flammable gases or vapor concentrations in air.

Purpose

This standard states Approval requirements for combustible gas detection instruments.

Approval criteria may include, but are not limited to, performance requirements, marking requirements, examination of manufacturing facility(ies), audit of quality assurance procedures, and a follow-up program.