ISO 3729:1976 pdf download.Fibre building boards一Determination of surface stability
1 SCOPE
This International Standard specifies a method for the determination of the surface stability, after a conditioning cycle, of hard and medium fibre building boards.
NOTE — This method is very similar to that tar the determination of surface finish (roughness) specified in ISO 3546.
2 FIELD OF APPLICATION
This International Standard applies to hard and medium fibre building boards, defined in ISO 818.
3 REFERENCES
ISO 766, Fibre building boards — Determination of dimensions.
ISO 818, Fibre building boards Definition — Classification.
ISO 3546, Fibre building boards — Dctermination of surface finish (roughness).
ISO..., Fibre building boards — Sampling, cutting and inspection.1)
4 PRINCIPLE
Measurement of the escape of air from a measuring head placed perfectly flat on the surface of a test piece conditioned in a specified atmosphere. Repetition of the measurement after conditioning in a second specified atmosphere, then again after reconditioning in the first specified atmosphere.
5 APPARATUS
See ISO 3546.
6 SAMPLING AND TEST PIECES
Sampling and cutting of the test pieces shall be carried out in accordance with the requirements of ISO . .
Test pieces shall be square, of side 300 mm (see ISO 766).
The test pieces shall be conditioned to constant mass2 in an atmosphere of relative humidity of 65 ± 5 % and at a temperature of 20 ± 2 °C.
7 PROCEDURE
7.1 Carefully clean all dust and loose particles from the smooth side of a test piece. Fix the test piece in the clamp so that the ten clamp holes are contained within the square. Place the gauge or gauges on the test surface in each of the holes and note the results obtained in millilitres per minute.
7.2 Condition the test pieces in an atmosphere of relative humidity of 90 % for 72 h. Carry out the procedure again as specified in 7.1.
7.3 Condition the test pieces in an atmosphere of relative humidity of 65 % to constant mass (see clause 6). Carry out the procedure again as specified in 7.1.
NOTE — For routine measurement of surface finish, a more sophisticated and quickly operated fixture with ten permanent integral gauges connectod in parallel has been designed. The device h a large capacity but the operator is required to observe a rigid discipline.
In this context it may be noted that the greatest care must be taken not to damage the smooth side of the gauges.
8 EXPRESSION OF RESULTS
Surface stability shall be expressed as the air leakage in millilitres per minute, between the surface of the test piece and the measuring device, to an accuracy of 1 mI/mm.
The results shall be observed at the following stages
— A : surface smoothness at the starting point of relative humidity 65 %;
— B : surface smoothness after conditioning at relative humidity 90 %;ISO 3729 pdf download.