Content Handbook F

Outline of method

The sample is brought to the prescribed temperature and transferred to a hydrometer cylinder at approximately the same temperature. The appropriate hydrometer is lowered into the sample and allowed to settle. The hydrometer is read and the temperature of the sample noted. If required, the cylinder and its contents are placed in a constant temperature bath to avoid excessive temperature variation during the test.

3.2 Pyknometer method

In this method the weights of equal volumes or the material and water are compared.

3.3 Density of suspension concentrates

3.3.1 Hydrometer method

Direct determination of density by hydrometer, density bottle or liquid displacement method has been shown to be unsuccessful because of aeration and viscosity effects. The density at 20 °C of a 1 : 1 aqueous dilution can be readily determined using a hydrometer and hence the actual density of the suspension concentrate can be calculated.

3.3.2 Density bottle method

A portion of the sample is weighed into a density bottle and diluted with water containing an anti-foam agent, using vacuum, if necessary to remove occluded air. The volume of sample taken is then found by making up to capacity with the anti-foam solution and weighing.