Foreword
1 Scope
2 Normative references
3 Terms, definitions and symbols
   3.1 Terms and definitions
   3.2 Symbols
4 Normal operating conditions
   4.1 Flow range
   4.2 Maximum working pressure
   4.3 Temperature range
   4.4 Range of gases
   4.5 Orientation
5 Metrological performance
   5.1 General
   5.2 Mode comparison
   5.3 Permissible errors
   5.4 Gas - air relationship
   5.5 Pressure absorption
   5.6 Metrological stability
   5.7 Immunity to contaminants in gas stream
   5.8 Installation effects
   5.9 Zero flow
   5.10 Reverse flow
   5.11 Low flow registration
   5.12 High flow registration
   5.13 Pulsed (unsteady) flow
   5.14 Temperature sensitivity
6 Construction and materials
   6.1 General
   6.2 Robustness of meter case
   6.3 Corrosion protection
   6.4 Casework decorative finish
   6.5 Ageing of non-metallic casework
   6.6 Ageing of external surfaces of the meter, including
        index windows and adhesion of the index window
   6.7 Protection against solar radiation
   6.8 Resistance to external humidity
   6.9 Flame retardance of external surfaces
   6.10 Resistance to storage temperature range
   6.11 Resistance to the effects of toluene/iso-octane vapour
   6.12 Resistance to water vapour
   6.13 Ageing
7 Optional features
   7.1 Pressure measuring point
   7.2 Resistance to high ambient temperature
   7.3 Meters with temperature conversion
   7.4 Ancillary devices (if fitted)
   7.5 Use in hazardous zones
8 Index
   8.1 Recording and storage
   8.2 Display
   8.3 Segmental display
   8.4 Non-volatile memory
   8.5 Display reset
9 Marking
   9.1 All meters
   9.2 Two-pipe meters
   9.3 Durability and legibility of marking
   9.4 Accompanying information
10 Software
   10.1 Requirements
   10.2 Test
11 Communications
   11.1 General
   11.2 Character transmission
   11.3 Communications protocol
   11.4 Data
   11.5 Test-mode
   11.6 Data optical port
   11.7 Galvanic port (optional)
   11.8 Diagnostics
12 Battery
   12.1 General
   12.2 Voltage interruptions
   12.3 Minimum operating voltage
   12.4 Battery life
13 Immunity to electromagnetic disturbances
   13.1 General
   13.2 Electrostatic discharge
   13.3 Radio frequency electromagnetic field
   13.4 Electromagnetic induction (power frequency)
   13.5 Electromagnetic induction (pulsed field)
   13.6 Radio interference suppression
14 Ultrasonic (acoustic) noise interference
   14.1 Requirements
   14.2 Test
15 Meters supplied for testing
Annex A (informative) Test gases
      A.1 General
      A.2 Test gas properties
Annex B (normative) Production requirements for gas meters
      B.1 Specification
      B.2 Technical requirements
      B.3 Certificates of conformity
Annex C (normative) Meters with gas temperature conversion
                    devices
      C.1 Scope
      C.2 Metrological performance
Annex ZA (informative) Relationship between this European
                       Standard and the Essential Requirements
                       of EU Directive 2004/22 Measuring
                       Instruments Directive
Bibliography