ASTM D891 is the Standard Test Method for Density of Liquid Industrial Chemicals.
It describes procedures for determining the density, relative density (specific gravity), or API gravity of liquid chemicals using hydrometers (or pycnometers). The method is widely used for product identification, quality control, inventory calculations, and the determination of the composition of binary mixtures. While specific gravity is generally not a direct measure of product quality, it is useful for detecting gross contamination or verifying product identity.
Density is determined by measuring the mass per unit volume of a liquid at a specified temperature and must be reported at a specified temperature (commonly 15°C, 20°C, or 25°C).
Temperature stability during measurement is essential for accuracy.
The use of a hydrometer is simple and fast but offers lower precision tha the pycnometer method.
Maintenance costs are low for this method compared to i.e. ASTM D4052.
Typical applications are industrial chemicals, solvents routine quality control and as backup or reference method.
ASTM D891 is a standard test method for determining the apparent specific gravity (relative density) of liquid industrial chemicals. The test measures the ratio of the mass of a given volume of a liquid to the mass of an equal volume of water at a specified temperature.
ASTM D891 includes two test procedures:
Test Method A – Hydrometer method: a rapid and simple procedure suitable for routine measurements.
Test Method B – Pycnometer method: a more accurate and precise procedure recommended for referee testing, viscous samples, or when higher accuracy is required.
Precision
The precision depends on the test method used:
Hydrometer method (Method A): Suitable for routine quality control, providing good repeatability but lower accuracy than the pycnometer method.
Pycnometer method (Method B): Offers the highest accuracy and precision and is the preferred method for dispute resolution and reference measurements. The standard provides repeatability and reproducibility data for representative industrial chemicals, although precision may vary depending on the product tested.
Test
ASTM D891 determines the apparent specific gravity, also referred to as relative density. This unit is demensionless (no unit).
