IEC 60079-29-4:2009

FOREWORD
1 Scope
2 Normative references
3 Terms and definitions
  3.1 Equipment
  3.2 Alarms
  3.3 Signals and indications
  3.4 Gaseous atmospheres
  3.5 Optical equipment
  3.6 Performance characteristics
4 General requirements
  4.1 Detection equipment
      4.1.1 Components
      4.1.2 Electrical assemblies and components
      4.1.3 Optical radiation
  4.2 Construction
      4.2.1 General
      4.2.2 Indicating devices
      4.2.3 Alarm or output functions
      4.2.4 Fault signals
      4.2.5 Adjustments
  4.3 Software-controlled equipment
      4.3.1 Conversion errors
      4.3.2 Software
      4.3.3 Data transmission
      4.3.4 Self-test routines
      4.3.5 Functional concept
5 Test requirements
  5.1 Introduction
  5.2 General requirements for tests
      5.2.1 Samples and sequence of tests
      5.2.2 Constructional checks
      5.2.3 Preparation of samples
      5.2.4 Equipment for calibration and test
  5.3 Normal conditions for test
      5.3.1 General
      5.3.2 Operating distance for laboratory tests
      5.3.3 Test gases
      5.3.4 Test gas integral concentrations
      5.3.5 Voltage
      5.3.6 Ambient temperature
      5.3.7 Ambient humidity
      5.3.8 Ambient atmosphere
      5.3.9 Preparation of equipment
      5.3.10 Stabilization
      5.3.11 Communications options
      5.3.12 Gas detection equipment as part of systems
  5.4 Test methods
      5.4.1 Initial preparation and procedure
      5.4.2 Unpowered storage
      5.4.3 Calibration curve (not applicable to alarm only
             equipment with fixed settings)
      5.4.4 Stability
      5.4.5 Alarm reliability
      5.4.6 Temperature variation
      5.4.7 Water vapour interference
      5.4.8 Vibration
      5.4.9 Drop test for portable and transportable equipment
      5.4.10 Alignment
      5.4.11 Time of response
      5.4.12 Minimum time to operate (spot-reading equipment)
      5.4.13 Battery capacity
      5.4.14 Power supply variations (externally powered
             equipment)
      5.4.15 Power supply interruptions and transients
      5.4.16 Recovery from power supply interruption
      5.4.17 Electromagnetic compatibility (EMC)
      5.4.18 Beam block fault
      5.4.19 Partial obscuration
      5.4.20 Long range operation
      5.4.21 Direct solar radiation (applicable for equipment
             intended for outdoor use)
6 Field verification equipment
7 Information for use
  7.1 Labelling and marking
  7.2 Instruction manual
Annex A (informative) - Water vapour test apparatus
Bibliography

IEC 60079-29-4:2009 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 meter to a few kilometres. Such equipment measures the integral concentration of the absorbing gas over the optical path in units such as LFL meter for flammable gases. This standard supplements and modifies the general requirements of IEC 60079-0. Where a requirement of this standard conflicts with a requirement of IEC 60079-0, the requirement of this standard shall take precedence. The contents of the corrigendum of August 2010 have been included in this copy.