ISO 7971-2:2009规定了通过参考标准测量仪器确保每百升测量仪器的质量的可追溯性的测试方法。每公顷或堆积密度的质量对谷物谷物具有商业重要性。存在不同性能的几种仪器，用于测量。 ISO 7971-2:2009还规定了实验室或收集或储存仓库中使用的国家标准仪器，二级标准仪器和测量仪器所需的性能

ISO 7971-2:2009 specifies a test method for ensuring the traceability of mass per hectolitre measuring instruments through reference to standard measurement instruments. The mass per hectolitre or bulk density is of commercial importance for grain cereals. Several types of instruments with varying performances exist for measuring it. ISO 7971-2:2009 also specifies the performances required of national standards instruments, secondary standards instruments, and measuring instruments used in laboratories or in collection or storage silos.