1.1.1 This part of IEC 61779 ANSI/ISA 12.13.01 (IEC 61779-1 through 5 Mod) specifies generalrequirements 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 vapourconcentrations with air. The apparatus, or parts thereof, are intended for use in potentially explosiveatmospheres (see 2.1.8 2.1.3) and in mines susceptible to firedamp. This document is supplemented bythe following parts, concerning the specific requirements for performance of the various types ofapparatus:
Part 2: Performance requirements for group I (mines) apparatus indicating up to a volume fraction of 5 % methane in air.
Part 3: Performance requirements for group I (mines) apparatus indicating up to a volume fraction of 100 % methane in air.
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 fractionof 100% gas.
NOTE 1 IEC 61779-1 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 tofiredamp) 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 I and 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.
1.1.2 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. Allsuch claims shall be verified and the test procedures shall be extended or supplemented wherenecessary to verify the claimed performance. The additional tests shall be agreed between themanufacturer and test laboratory.
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