What is the purpose of this test?

To determine the 'openness' or degree of fiberization of chrysotile asbestos, which affects its performance in asbestos-cement products.

What is the principle behind the Dyckerhoff method?

It is an air permeability test. It measures the resistance to airflow through a compressed pad of asbestos fibres; higher resistance (longer time) indicates a less 'open' fibre structure.

Is this standard still active?

No, IS 9690:1980 has been officially withdrawn by the Bureau of Indian Standards (BIS).

What does a high openness value mean?

A high time value (in seconds) indicates a 'closed' or less fiberized sample, which may not disperse well in a cement matrix.

IS 9690

: 1980

Method of test for determination of openness or fabrication of chrysotile asbestos fibre by air permeability method using Dyckerhoff apparatus

CurrentRareTesting MethodMaterials Science · Cement Matrix Products

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This standard outlines the test method for determining the openness or degree of fiberization of chrysotile asbestos fibres. The procedure involves measuring the time taken for a fixed volume of air to pass through a prepared sample of asbestos under a constant pressure head using the Dyckerhoff apparatus. The resulting time in seconds is reported as the openness value, which is critical for evaluating the suitability of the fibre for use in asbestos-cement products.

Method of test for determination of openness or fabrication of chrysotile asbestos fibre by air permeability method using Dyckerhoff apparatus

Quick Reference Values

Sample Mass10.0 ± 0.1 g

Test Cylinder Diameter50 mm

Perforated Plunger Mass1 kg

Air Volume for Test1000 cm³

Key Formulas

Openness Value (S) = T — Formula to calculate the result, where S is the openness value in seconds (T) required for a specific volume of air to pass through the sample.

Practical Notes

This standard has been WITHDRAWN by BIS. The use of asbestos is now heavily restricted or banned in India due to severe health risks.

Handling asbestos fibres requires stringent safety protocols, including respiratory protection and specialized ventilation, to prevent inhalation of carcinogenic fibres.

The 'openness' value correlates to how well the fibre will disperse in a cement slurry; a higher value indicates a less open fibre.