This part of ANSI/ISA-12.13.01 (IEC 61779-1 through 5 Mod) specifies general requirements for construction and testing and describes the test methods that apply to portable, transportable and fixed apparatus for the detection and measurement of flammable gas or vapour concentrations with air. The apparatus, or parts thereof, are intended for use in potentially explosive atmospheres (see 2.1.3). This document is supplemented by the following parts, concerning the specific requirements for performance of the various types of apparatus:

Part 4: Performance requirements for group II (non-mining) apparatus indicating up to a volume fraction of 100% lower explosive limit

Part 5: Performance requirements for group II (non-mining) apparatus indicating up to a volume fraction of 100% gas

NOTE 1 Part 1 of ANSI/ISA-12.13.01 (IEC 61779-1 through 5 Mod), in association with the parts referred to above, is intended to provide for the supply of apparatus giving a level of safety and performance suitable for general-purpose applications. However, for specific applications a prospective purchaser (or an appropriate authority) may additionally require apparatus to be submitted to particular tests or approval. For example, group I apparatus (i.e. apparatus to be used in mines susceptible to firedamp) may not be permitted to be used without the additional and 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 Group II apparatus indicating up to a volume fraction of 100% methane and group II apparatus indicating up to a volume fraction of 100% gas are suitable for use only with the specific gases for which they have been calibrated.

NOTE 3 For the purpose of this document, 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 4 For the purpose of this document, the terms "explosive gas atmosphere" and "flammable gas atmosphere" are deemed to be synonymous.

This document is applicable when an apparatus manufacturer makes any claims regarding any special features of construction or superior performance that exceed these minimum requirements. 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.

This document is applicable to flammable gas detection apparatus intended to provide an indication, alarm or other output function, the purpose of which is to give a warning of potential explosion hazard and in some cases to initiate automatic or manual protective action(s).

This document is applicable to apparatus, including the integral sampling systems of aspirated apparatus, intended to be used for commercial and industrial (non-residential) safety applications.

This document does not apply to external sampling systems, or to apparatus of laboratory or scientific type, or to apparatus used only for process control purposes. It also does not apply to open path (line of sight) area monitors (refer to CENELEC prEN 50241-1 and prEN 50241-2, February 1996). For apparatus used for sensing the presence of multiple gases, this document applies only to the portion sensing the presence of flammable gas or vapor.