NIMT density reference material based on water according to ISO Guide 35

Certified Reference Materials (CRMs) are widely used to provide metrological traceability of products. Density CRMs are employed to verify or calibrate measuring equipment used to measure density of liquid, e.g. density meters and flowmeters. Generally, a small amount of liquid per unit are produced as density CRMs. The small amount of reference liquid is unsuitable for calibration of equipment requiring large amount of liquid sample. Due to this limitation, the density CRMs with the size of 20 litres per unit were produced. The material used was filtered water. A between-unit homogeneity of filtered water was studied and analysed using one-way analysis of variance (ANOVA). A stability study was also performed to predict the shelf life of material. This material was certified using an oscillation-type density meter. The certified density of the reference material at 20°C was 998.201 kg m−3 with uncertainty of 0.042 kg m−3