1.1 本试验方法涵盖了汽缸油和黑油沉淀数的测定，也可用于其他润滑油。 1.2 以SI单位表示的值将被视为标准值。本标准不包括其他计量单位。 1.3 本标准并不旨在解决与其使用相关的所有安全性问题（如果有）。本标准的使用者有责任在使用前建立适当的安全、健康和环境实践并确定法规限制的适用性。 1.4 本国际标准是根据世界贸易组织技术性贸易壁垒（TBT）委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认的标准化原则制定的。======意义和用途====== 4.1 完全精炼的石油通常不含石脑油不溶性物质。半精炼或黑色油经常含有一些石脑油不溶性物质（有时称为 沥青质 ).该测试测量油中石脑油不溶性物质的量。这个量被报告为降水数。

1.1 This test method covers the determination of the precipitation number of steam cylinder stocks and black oils, and can be used for other lubricating oils. 1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.3 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. 1.4 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. ====== Significance And Use ====== 4.1 Fully refined petroleum oils normally contain no naphtha-insoluble material. Semirefined or black oils frequently contain some naphtha-insoluble material (sometimes referred to as asphaltenes ). This test measures the amount of naphtha-insoluble material in the oil. This quantity is reported as the precipitation number.