IS 9690 : 1980Method of test for determination of openness or fabrication of chrysotile asbestos fibre by air permeability method using Dyckerhoff apparatus
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IS 9690:1980 is the Indian Standard (BIS) for method of test for determination of openness or fabrication of chrysotile asbestos fibre by air permeability method using dyckerhoff apparatus. 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
! This standard has been WITHDRAWN by BIS.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.
asbestoschrysotilefibrecement
International Equivalents
Similar International Standards
ASTM D2752 - 12(2018)ASTM International, USA
HighCurrent
Standard Test Methods for Air Permeability of Asbestos Fibers
Defines test methods for air permeability of asbestos, including a specific procedure for the Dyckerhoff apparatus.
ISO 10394-1:1991International Organization for Standardization
HighWithdrawn
Measurement of the degree of opening of asbestos fibres — Part 1: Air-permeability method
Specified an air permeability method for measuring the degree of opening, directly aligning with the purpose of IS 9690.
An influential industry method for determining fibre openness, forming the basis for many subsequent national/international standards.
Key Differences
≠IS 9690 focuses exclusively on the Dyckerhoff apparatus, whereas ASTM D2752 is a broader standard that covers multiple apparatus types (e.g., Dyckerhoff, Fraser, Ploof) for measuring air permeability.
≠ASTM D2752 specifies a compressive load of 2.2 kg (5 lb) on the piston to compact the sample, providing higher precision. IS 9690 vaguely states to apply 'a light pressure' with the piston.
≠ASTM D2752 requires conditioning of the test specimen at a specified temperature and humidity for referee purposes, which is not mentioned in IS 9690.
≠The tolerance for agreement between replicate tests differs. IS 9690 requires two results to be within 7%, while ASTM D2752 allows a difference of up to 10% before a third test is required.
Key Similarities
≈All standards are based on the same physical principle: measuring the time taken for a fixed volume of air to pass through a compressed pad of asbestos fibre under a pressure differential, based on the Kozeny-Carman relationship.
≈Both IS 9690 and the Dyckerhoff procedure in ASTM D2752 specify the use of a 10 g test specimen.
≈The core design and operation of the Dyckerhoff apparatus, including the permeability cell, piston, and water manometer, are functionally identical across the standards that reference it.
≈The final calculation to derive the 'Dyckerhoff Number' (D) uses a nearly identical logarithmic formula, ensuring that results are comparable between methods.
Parameter Comparison
Parameter
IS Value
International
Source
Test Specimen Mass
10.0 g
10.0 ± 0.1 g
ASTM D2752
Apparatus Scope
Dyckerhoff apparatus only
Dyckerhoff, Fraser, and other apparatus
ASTM D2752
Sample Compression Load
A light pressure
2.2-kg (5-lb) weight on piston
ASTM D2752
Formula for Dyckerhoff No. (D)
D = 400 log (t2/t1) + 100
D = 101 + 400 log10 (T2/T1)
ASTM D2752
Number of Determinations
Two
At least two
ASTM D2752
Acceptance Criteria for Replicates
Results shall not differ by more than 7%
Agreement within 10% (if not, test a third)
ASTM D2752
Sample Conditioning (for referee tests)
Not specified
Required at specified temp/humidity (e.g., 21°C & 50% RH)
ASTM D2752
⚠ Verify details from original standards before use
Key Values4
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.
Tables & Referenced Sections
Key Tables
No tables data
Key Clauses
No clauses data
Frequently Asked Questions4
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.