【国外标准】 Standard Practice for Sampling Liquefied Petroleum (LP) Gases, Manual Method

5.1 Samples of liquefied petroleum gases are examined by various test methods to determine physical and chemical characteristics and conformance with specifications.5.2 Equipment described by this practice may be suitable for transportation of LPG samples, subject to applicable transportation regulations.1.1 This practice covers equipment and procedures for obtaining a representative sample of specification Liquefied Petroleum Gas (LPG), such as specified in Specification D1835, GPA 2140, and comparable international standards. This standard is applicable to flow-through cylinders with two valves and is not applicable to single valve cylinders or larger LPG sample containers such as those utilized for barbecue grills and/or forklift cylinders.1.2 This practice is suitable for obtaining representative samples for all routine tests for LP gases required by Specification D1835. In the event of a dispute involving sample integrity when sampling for testing against Specification D1835 requirements, Practice D3700 shall be used as the referee sampling procedure.1.3 This practice may also be used for other Natural Gas Liquid (NGL) products that are normally highly volatile, single phase materials (NGL mix, natural gasoline, field butane, etc.), defined in other industry specifications or contractual agreements, where use of open sample containers would risk the loss of volatile components. It is not intended for non-specification products that contain significant quantities of undissolved gases (N2, CO2), free water or other separated phases, such as raw or unprocessed gas/liquids mixtures and related materials. The same equipment can be used for these purposes, but additional precautions are generally needed to obtain representative samples of multiphase products (see Appendix X1 on Sampling Guidelines in Practice D3700).NOTE 1: Practice D3700 describes a recommended practice for obtaining a representative sample of a light hydrocarbon fluid and the subsequent preparation of that sample for laboratory analysis when dissolved gases are present. Use of Practice D1265 will result in a small but predictable low bias for dissolved gases due to the liquid venting procedure to establish the 20 % minimum ullage.1.4 This practice includes recommendations for the location of a sample point in a line or vessel. It is the responsibility of the user to ensure that the sampling point is located so as to obtain a representative sample.1.5 The values stated in SI units are to be regarded as standard.1.5.1 Exception—Non-SI units are shown in parentheses for information only.1.6  This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.