吸油数（OAN）是衡量炭黑吸收液体能力的指标。这种性质是炭黑结构的函数。邻苯二甲酸二丁酯（DBP）或石蜡油均可用于标准颗粒级，包括ASTM D1765中发现的N系列炭黑，尽管与使用DBP油的OAN试验相比，在某些特殊炭黑和粉末炭黑上使用石蜡油的OAN试验可能会导致不可接受的差异。虽然研究表明这两种油的精度相当，但石蜡油的优点是不含脂肪- 危险的 ISO 4656:2012规定了一种使用吸收计测定橡胶工业用炭黑吸油值的方法。 同样的方法用于测定炭黑压缩样品的吸油数。附录中描述了压缩样品的制备程序。

Oil absorption number (OAN) is a measure of the ability of a carbon black to absorb liquids. This property is a function of the structure of the carbon black. Either dibutyl phthalate (DBP) or paraffin oil is acceptable for use with standard pelleted grades, including N？series carbon blacks found in ASTM D1765, although OAN testing using paraffin oil on some speciality blacks and powder blacks might result in unacceptable differences as compared to OAN testing using DBP oil. While studies have shown the two oils to give comparable precision, paraffin oil offers the advantage of being non-hazardous. ISO 4656:2012 specifies a method using an absorptometer for the determination of the oil absorption number of carbon black for use in the rubber industry. The same method is used for the determination of the oil absorption number of compressed samples of carbon black. The procedure for the preparation of the compressed samples is described in an annex.