Preface This is the fifth edition of CSA/ANSI NGV 2, Compressed natural gas vehicle fuel containers. This Standard was prepared by the NGV 2/HGV 2 Technical Subcommittee on Standards for Compressed Natural Gas and Compressed Hydrogen Vehicle Fuel Containers, under the jurisdiction of the Automotive Technical Committee, and has been formally approved by the Technical Committee, and the American National Standards Institute. Previous editions of this Standard, and addenda thereto, approved by the American National Standards Institute are as follows: NGV 2-1992 NGV 2-1998 NGV 2-2000 / NGV 2a-2001 NGV 2-2007 / NGV 2a-2012 / NGV 2b-2012 Scope 1.1 General This Standard contains requirements for the material, design, manufacture, and testing of serially produced, refillable Type NGV 2 containers intended only for the storage of compressed natural gas for vehicle operation. These containers are to be permanently attached to the vehicle. This standard applies to containers up to and including 1 000 liters (35.4 ft3) water capacity. 1.2 Container type Type NGV 2 containers are designated as follows: Type 1 - Metal. Type 2 - Resin impregnated continuous filament with metal liner with a minimum burst pressure of 125 percent of service pressure. This container is hoop-wrapped. Type 3 - Resin impregnated continuous filament with metal liner. This container is full- wrapped. Type 4 - Resin impregnated continuous filament with a nonmetallic liner. 1.3 Alternative construction or materials All specifications as to construction or materials set forth herein may be satisfied by the construction or materials actually prescribed or such other construction or materials as will provide at least equivalent level of performance. Additional tests may be required to evaluate potential failure modes that pertain to the new construction or materials that are not specifically addressed in this Standard. 1.4 Units of measure This Standard contains SI (metric) units with yard/pound quantities for reference purposes, the purpose being to allow the Standard to be used in SI (metric) units. IEEE/ASTM SI 10, or ISO 80000-1, is used as a guide in making metric conversion from inch/pound quantities. If a value for a measurement and a corresponding value in other units are stated, the first stated value is to be regarded as the requirement. The given corresponding value may be approximate. If a value for a measurement and a corresponding value in other units, are both specified as a quoted marking requirement, the first stated unit, or both are to be provided. 1.5 Terminology In this Standard, "shall" is used to express a requirement, i.e., a provision that the user is obliged to satisfy in order to comply with the standard; "should" is used to express a recommendation or that which is advised but not required; and "may" is used to express an option or that which is permissible within the limits of the standard. Notes accompanying clauses do not include requirements or alternative requirements; the purpose of a note accompanying a clause is to separate from the text explanatory or informative material. Notes to tables and figures are considered part of the table or figure and may be written as requirements. Annexes are designated normative (mandatory) or informative (non-mandatory) to define their application.