前言:这是CSA/ANSI NGV 4.6《天然气分配系统的手动阀门》的第二版。它取代了1999年出版的上一版ANSI/IAS NGV 4.6/CSA 12.56。本标准包括天然气分配系统手动阀门部件的安全操作、坚固耐用的结构和性能测试，在下文给出的限制和本标准的范围内。本标准基于成熟的工程原理、研究以及天然气公用事业公司、制造商、用户和其他具有专业经验的人的综合专业知识。本标准中的任何内容均不得以任何方式被视为表明质量指标超出了其包含的规定。 其设计允许产品符合本协议规定的要求。在准备过程中，充分认识到通过巧妙设计进行改进的可能性。本标准可能会被修订，因为进一步的经验和调查可能表明它是必要和可取的。CSA集团及其各自的实验室不承担或承诺履行制造商或任何其他方的任何责任。CSA集团不对因使用、解释或依赖本标准而产生的或与之相关的任何损害承担任何义务或责任，包括间接损害。 建议美国国家和加拿大标准协会统一标准的用户，其范围内的设备/产品/活动可能受到联邦、州、省或地方各级的监管。强烈敦促用户通过适当渠道调查这种可能性。如果与本标准发生冲突，应遵守联邦、州、省或地方法规。CSA集团承认，该标准的制定部分是由于加拿大自然资源部的财政支持。本标准不适用于符合联邦机动车安全标准（FMVSS）或加拿大天然气动力车辆机动车安全标准（CMVSS）的机动车原始制造过程中纳入的燃油系统部件。 本标准的制定符合加拿大标准委员会对加拿大国家标准的要求。CSA集团已将其作为加拿大国家标准发布。范围:1.1本标准范围内的阀门类型这些要求适用于压缩天然气的手动阀门。1.2不在本标准范围内的阀门类型这些要求不适用于气瓶切断阀。1.3本标准中的术语“应”用于表示要求，即用户为遵守本标准而有义务满足的规定；“应该”用于表示建议或建议但不需要的建议； “可”用于表示一个选项或在标准范围内允许的选项。注释随附条款不包括要求或替代要求；随附条款的注释的目的是将解释性或信息性材料与文本分开。表和图的注释被视为表或图的一部分，可以作为要求编写。附件被指定为规范性（强制性）或信息性（非强制性）以定义其应用。1.4测量单位国际单位制给出的数值为本标准中的记录单位。括号中给出的值仅供参考和比较。

Preface:This is the second edition of CSA/ANSI NGV 4.6,Manually operated valves for natural gas dispensing systems. It supersedes the previous edition, ANSI/IAS NGV 4.6/CSA 12.56, published in 1999.This Standard encompasses the safe operation, substantial and durable construction, and performance testing of components for manually operated valves for natural gas dispensing systems, within limitations given below and in the scope of this Standard.This Standard is based on proven engineering principles, research, and the combined expertise of gas utilities, manufacturers, users, and others having specialized experience.Nothing in this Standard is to be considered in any way as indicating a measure of quality beyond compliance with the provisions it contains. It is designed to allow compliance of products which may exceed that specified in the provisions herein. In its preparation, full recognition has been given to possibilities of improvement through ingenuity of design. This Standard is subject to revision as further experience and investigation may show it is necessary and desirable.CSA Group, and their respective Laboratories, do not assume or undertake to discharge any responsibility of the manufacturer or any other party. CSA Group shall not incur any obligation or liability for damages, including consequential damages, arising out of or in connection with the use, interpretation of, or reliance upon this Standard.Users of this Harmonized American National and Canadian Standards Association Standard are advised that the devices/products/activities within its scope may be subject to regulation at the Federal, state, provincial, or local levels. Users are strongly urged to investigate this possibility through appropriate channels. In the event of a conflict with this Standard, the Federal, state, provincial, or local regulations should be followed.CSA Group acknowledges that the development of this Standard was made possible, in part, by the financial support of Natural Resources Canada.This Standard does not apply to fuel system components that will be incorporated during original manufacture of motor vehicles which comply withFederal Motor Vehicle Safety Standards (FMVSS) or Canadian Motor Vehicle Safety Standards (CMVSS)for Natural Gas Powered Vehicles.This Standard has been developed in compliance with Standards Council of Canada requirements for National Standards of Canada. It has been published as a National Standard of Canada by CSA Group.Scope:1.1 Types of valves in the scope of this StandardThese requirements apply to manually operated valves for compressed natural gas.1.2 Types of valves not in the scope of this StandardThese requirements do not apply to cylinder shut-off valves.1.3 TerminologyIn 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.1.4 Units of measureThe values given in SI units are the units of record for the purposes of this Standard. The values given in parentheses are for information and comparison only.