ONORM EN 334 : JUN 2009

Foreword
1 Scope
2 Normative references
3 Definitions and symbols
      3.1 Terminology
             3.1.1 Gas pressure regulator
             3.1.2 Main components
             3.1.3 Accessories
      3.2 Control variables
             3.2.1 Reference values
             3.2.2 Variables in the controlling process
             3.2.3 Possible values of all variables
             3.2.4 Terms pertinent to the controlled variable
      3.3 Operating features in stable conditions
             3.3.1 Stable conditions
             3.3.2 Performance curve
             3.3.3 Hysteresis band
             3.3.4 Family of performance curves
             3.3.5 Features pertinent to accuracy
             3.3.6 Features pertinent to lock-up behaviour
      3.4 Further functional terminology
             3.4.1 Pressures pertinent to design of gas
                      pressure regulator
             3.4.2 Nominal pressure
             3.4.3 Operating temperature range
4 Construction requirements
      4.1 General requirements
             4.1.1 Operational requirements
             4.1.2 Gas pressure regulators with built-in
                      safety devices
             4.1.3 End connections
             4.1.4 Nominal pressures
             4.1.5 Nominal sizes and face-to-face
                      dimensions
      4.2 Materials
             4.2.1 Chemical resistance requirements
             4.2.2 Requirements for metallic materials
             4.2.3 Requirements for elastomers (including
                      vulcanised rubbers)
      4.3 Strength of housings
             4.3.1 Regulator body
             4.3.2 Other pressure containing parts
             4.3.3 Minimum values of safety factors
5 Functional requirements
      5.1 General
             5.1.1 Mounting position
             5.1.2 Sound emission
      5.2 Tightness and sealing
             5.2.1 External tightness
             5.2.2 Internal sealing
      5.3 Control classifications
             5.3.1 Accuracy under stable conditions
             5.3.2 Lock-up behaviour
             5.3.3 Stable conditions
6 Gas pressure regulator sizing
      6.1 Flow behaviour
      6.2 Sizing equations for the calculation of
             volumetric flow rates of a gas pressure
             regulator with its control member in its
             mechanically fully open position
             6.2.1 Normal calculations
             6.2.2 Practical calculations
             6.2.3 Simplified calculations
      6.3 Calculation of the maximum accuracy flow rate
      6.4 Inherent flow characteristics
      6.5 Calculation of volumetric flow rates for
             partially open gas pressure regulators
7 Testing
      7.1 Types of tests
             7.1.1 General
             7.1.2 Type test
             7.1.3 Selection of test samples
             7.1.4 Manufacturer's test
             7.1.5 Surveillance
      7.2 Test and verification methods
             7.2.1 Dimensional check and visual
                      inspection
             7.2.2 Materials check
             7.2.3 Verification of the strength of the
                      pressure containing parts
             7.2.4 Shell strength test
             7.2.5 External tightness test
             7.2.6 Functional tests
             7.2.7 Final inspection
8 Documentation
      8.1 Documentation related to the type test
             8.1.1 Documentation required prior to the
                      type test
             8.1.2 Test report
      8.2 Documentation related to the manufacturer's tests
             8.2.1 Documentation provided at the request
                      of the customer
             8.2.2 Documentation provided with the regulator
      8.3 Documentation related to surveillance
             8.3.1 Documentation to be available for
                      surveillance
             8.3.2 Surveillance report
9 Marking
      9.1 General requirements
      9.2 Markings for the various connections
      9.3 Marking of built-in safety devices
Annex A (informative) Use of allowable pressure
Annex B (informative) Alternative methods for the determination
                      of the accuracy class, the lock-up
                      pressure class, the maximum accuracy
                      flow rate, the flow coefficients and the
                      verification of the hysteresis band
      B.1 - General
      B.2 - Test methods
            B.2.1 - Direct acting gas pressure regulator
            B.2.2 - Pilot controlled gas pressure regulators
      B.3 - Determination of flow coefficients for larger
            capacity regulators
Annex C (informative) Inspection certificate
Annex D (informative) Acceptance test
Annex E (informative) Conformity evaluation
      E.1 - General
      E.2 - Manufacturer's conformity evaluation
      E.3 - Third party conformity evaluation
            E.3.1 - Introduction
            E.3.2 - Procedure
            E.3.3 - Selection of test samples
      E.4 - Issue of the certificate of conformity
Annex F (informative) Seat leakage
Annex G (informative) Order specification
      G.1 - Minimum specifications
            G.1.1 - Details of construction
            G.1.2 - Dimensions
            G.1.3 - Performance
      G.2 - Optional specifications
Annex H (informative) A-deviations
Annex J (informative) Bibliography

Provides constructional and functional requirements, regulator sizing, testing, documentation and marking of gas pressure regulators used in the pressure regulating stations: - for inlet pressures up to 100 bar and nominal diameters up to DN 400; - for an operating temperature range from -20 degree C to +60 degree C, which operate with fuel gases of the 1st and 2nd family in accordance with EN 437 in transmission and distribution networks and also in commercial and industrial installations.