This standard specifies the laboratory method for determining the length distribution of chrysotile asbestos fibres. The procedure involves wet classification using a Bauer-McNett classifier, which separates a fibre sample into different length fractions by passing a water suspension of the fibres through a series of standard screens.
Method of test for length distribution (wet classification of fibre length) of chrysotile asbestos fibre using Bauer Mcnett classifier
Quick Reference Values
Test specimen mass10 ± 0.05 g
Classifier tank capacity22.5 litres
Water flow rate into each tank11.35 ± 0.20 litres/min
Classifier impeller speed580 ± 20 rev/min
Disintegration period20 min
Standard screen mesh sizes4, 14, 35, and 200 mesh
Key Formulas
Percentage retained on a screen = (Mass of fibre on screen / Total initial mass of sample) x 100
Practical Notes
This standard is for a material (asbestos) that is a known carcinogen and is now heavily regulated or banned in many applications. Extreme health and safety precautions, including appropriate PPE and ventilation, are mandatory.
The Bauer-McNett classification result is a critical quality control parameter for asbestos fibres, as fibre length significantly influences the mechanical properties of end products like asbestos-cement sheets and pipes.
This standard may be withdrawn or superseded by health and safety regulations. Users should verify its current status with BIS and relevant environmental/health authorities.