NEN EN 50303 : 2000

Foreword
Introduction
1 Scope
2 Normative references
3 Definitions
4 General
5 Category M1 equipment having the requisite level of
      protection in the event of two faults occurring
      independently of each other
6 Category M1 equipment having the requisite level of
      protection using a second independent means
7 Requirements for Category M1 flammable gas detectors
      with hot wire or hot pellistor sensing heads
8 Requirements for Category M1 systems
9 Type testing
10 Marking requirements
11 Instructions

Gives the design, construction, testing and marking requirements for Group I, Category M1 equipment intended to remain functional in underground parts of mines, as well as those parts of surface installations such as mines endangered by firedamp and/or coal dust clouds under normal atmospheric conditions of pressures ranging from 0,8 bar to 1,1 bar and temperatrues ranging from -20 deg. C to +60 deg. C.