ISO 3729:1976 pdf download – Fibre building boards – 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 for 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 REFER ENCES
ISO 766，Fibre building boards – Determination of dimensions.
ISO 818，Fibre building boards – Definition – Classifi- cation.
ISO 3546，Fibre building boards – Determination of surface finish (roughness).
ISO … Fibre building boards 一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.
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一For routine measurement of surface finish, a more sophisticated and quickly operated fixture with ten permanent integral gauges connected in paralle! has been designed. The device has 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.
NOTE – If results are obtained which differ considerably from the mean, the reason must be established. The first cause to be examined is poor cleaning. Blowing the test surface clean or wiping it off with the fingers will immediately result in moisture changes and is not permitted, in viow of the changes caused on the tust surface. Subsequently, the surface under the clamp hole concerned should be examined. If anything abnormal is thereby obsorved, a descriptive note must be made and the result struck from the list for the calculation of mean values. Reasons justifying this are damage due to external cuases, damaged calendering plate or other markedly local defects in manufacture. Shives, bark flakes, distinct fibrous knots and similar defects which may be assumed to be widely present shall not justify deletion of the reading.