Viscosity Determination Vertical Falling Ball Determination

Scope and description of falling ball assay

This method is suitable for the determination of transparent coating products with high viscosity, and the measured viscosity is the conditional viscosity. That is, at a certain temperature, the time required for a steel ball of a certain specification to fall vertically through the upper and lower scale lines of the glass tube containing the sample, expressed in seconds (B).

Falling ball test equipment and materials

1) The specifications and dimensions of the falling ball viscometer are shown in Figure 1-1-30. The viscometer is composed of commercial parts: glass tube and steel ball. The length of the glass tube is 350mm, and the inside is (25±0.25)mm. There is a scale line 50mm away from the edge of the nozzle at both ends, and the same distance between the two lines is 250mm. There are cork stoppers on the upper and lower ends of the nozzle, and an iron nail in the middle of the upper end of the cork. The glass tube is fixed on the shelf (measured by pin). The diameter of the steel ball is (8 ± 0.03) mm,

Its specifications should meet the requirements of 8m in the GB308 standard.

2) The stopwatch scale is 0.2s.

3) permanent magnet.

Falling Ball Viscosity Determination Method

1) Pour the transparent sample into the glass tube so that the sample is 40mrn above the upper scale line. Put in the steel ball, put the cork with iron nails on the device. Place the permanent magnet on the cork with iron nails.

2) Put the pipe in order to make the iron nails absorb the steel ball, then turn it over and fix it on the rack. Using a plumb bob, adjust the glass tube to make it vertical. Take away the long-term broken iron, let the steel ball fall freely, and when the steel ball just falls to the scale line, immediately start the stopwatch with your shoulder. Stop the stopwatch timing when the steel ball falls to the lower scale line. The viscosity of the sample is represented by the time (s) for the steel ball to pass through the two scale lines.

The result shows

Take the average value of the two measurements as the measurement result, and the difference between the two measured values ​​should not be greater than 3% of the average value

Reference standard

National Standard GB/T 1723 "Determination of Viscosity of Coatings"