NEN EN 331 : 2015
Current
The latest, up-to-date edition.
MANUALLY OPERATED BALL VALVES AND CLOSED BOTTOM TAPER PLUG VALVES FOR GAS INSTALLATIONS FOR BUILDINGS
12-01-2013
Foreword
1 Scope
2 Normative references
3 Definitions
4 Classification
4.1 Pressure classes
4.2 Temperature classes
5 Construction requirements
5.1 General
5.1.1 Materials
5.1.2 Construction
5.1.3 Connections
5.1.4 Seals
5.2 Operation
5.3 Stops
5.4 High temperature resistance
6 Performance requirements
6.1 General
6.2 Leak-tightness
6.3 Rated flow rate
6.4 Operating torque
6.5 Torque and bending resistance
6.6 Durability
6.6.1 Endurance
6.6.2 Resistance to low temperature
6.7 Stop resistance
7 Test methods
7.1 General
7.1.1 Test conditions
7.1.2 Test sequence
7.2 Leak-tightness
7.2.1 General
7.2.2 Closure parts, external leak-tightness
7.2.3 Internal leak-tightness
7.3 Rated flow rate
7.3.1 Apparatus
7.3.2 Procedure
7.4 Operating torque
7.5 Torque and bending resistance
7.5.1 General
7.5.2 Sequence of torsion and bending moment tests for
valves
7.5.3 Procedure for valves with flexible connection (see
Figure 5)
7.6 Durability
7.6.1 Endurance test
7.6.2 Resistance to low temperature
7.6.3 Durability of sealing materials
7.6.4 Protection pf external surfaces
7.6.5 Resistance to humidity
7.7 Angular seal
7.8 Stop resistance
8 Marking, installation and operating instructions
and packaging
8.1 Marking of the valve
8.2 Installation and servicing operating instructions
8.3 Packaging
Annex A (informative) Leak-tightness test - Volumetric
method
Annex B (informative) Leak-tightness test - Pressure loss
method
Annex C (informative) High temperature resistance
Annex D (informative) A-deviations
Annex E (informative) Bibliography
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