Abstract

The method can be used for all types of coating powder, is simple to carry out, but requires more expensive instrumentation than is often used for density determinations. It is based on the determination of the volume of a weighed test portion by measuring the volume of the gas displaced. This is achieved by equalizing the pressure difference which arises due to the displacement of the gas.

Scope

This document specifies a method for the determination of density for all types of coating powders using a gas comparison pycnometer.

Principle

The density is calculated from the mass and the volume of the test portion. The volume of a weighed test portion is determined by measuring the volume of gas displaced within a receptacle when the test portion is introduced. This is achieved by measuring the pressure difference which arises due to the displacement of the gas.

Materials

Helium or nitrogen, minimum Grade 4,8, in a steel cylinder.

Other high purity gases may be used provided that the product under test is not affected and this deviation from the method is noted in the test report.

Apparatus

Ordinary laboratory apparatus, together with a gas comparison pycnometer for the automatic or manual determination of density。

The essential design of a typical gas comparison pycnometer employs a displacement gas as the medium, outlined in Figure 1. It consists of two chambers, sample and reference, of equal dimensions. The chambers are connected by a valve and a pressure difference meter. The test portion is placed in the sample chamber. The displacement gas is allowed to flow from one chamber into the other chamber and the resulting pressure difference is measured.

NOTE Automated gas pycnometers can help minimize errors compared with manual pycnometers. Manual pycnometers may be used and due care is needed during testing and measurement.

*Contact us (sales@goldapp.com.cn) to get this downloaded PDF*