Preface This is the second edition of CSA/ANSI NGV 6.1, Compressed natural gas (CNG) fuel storage and delivery systems for road vehicles. It supersedes the previous edition published in 2016. The first edition of CSA NGV 6.1 was a Recommended Practice that provided a recommended standard practice for vehicle fuel systems. It was written in mandatory language to accommodate its adoption by anyone wishing to do so. The second edition transitioned to a National Standard. Scope 1.1 This Standard applies to the design, installation, inspection, repair, and maintenance of a fuel storage and delivery system installed in an on road vehicle for use with compressed natural gas (CNG). This includes a fuel system on a self-propelled vehicle for the provision of motive power. Note: This Standard is intended to cover the fuel storage and delivery system as defined in Figure 1. Elements downstream of the regulation device(s) or stage(s) such as the low pressure delivery line and injectors are not included in the Scope of this Standard. 1.2 This Standard does not apply to: a) stationary engines; b) mobile equipment using natural gas as a fuel for other than propulsion; c) electronic control module or controls strategy of a fuel management system; d) liquefied natural gas (LNG) fuel storage systems; or e) compressed natural gas (CNG) gaseous portion of LNG vehicles. Future editions of this Standard may include: a) liquefied natural gas (LNG) fuel storage system; b) compressed natural gas (CNG) portion of an LNG vehicle; c) storage or utilization of natural gas on boats or trains; d) powered industrial trucks; e) off road applications including mining applications, all-terrain vehicles; and f) motorcycles. 1.3 Regulatory requirements may supersede the requirements of this Standard. 1.4 All references to pressure throughout this Standard are to be considered gauge pressures, unless otherwise specified. 1.5 This Standard contains SI (Metric) with corresponding English units, the purpose being to allow the Standard to be used in SI (Metric) units. American National Standard for Metric Practice, IEEE/ASTM SI 10, or ISO 80000-1, Quantities and units — Part 1: General, is used as a guide in making English conversion from metric units. 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. Where the word "gallon" is used in this Standard, it indicates a U.S. gallon equivalent to 3.785 liters water capacity. 1.6 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 existing codes and this 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.