ISO 5636-4:2013 pdf download.Paper and board一Determination of air permeance (medium range)一Part 4:Sheffield method.
This part of ISO 5636 specifies the Sheffield method for determining the air permeance of paper and board using the Sheffield apparatus.
It is unsuitable for rough-surfaced materials, which cannot be securely clamped to avoid leakage.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, oniy the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 186, Paper and board — Sampling to determine average quality
ISO 187, Paper, board and puips — Standard atmosphere for conditioning and testing and procedure for
monitoring the atmosphere and conditioning of samples
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
air permeance
mean air flow rate through unit area under unit pressure difference in unit time, under specified conditions
Note 2 to entry: This property is called air permeance, and not air permeability, because it is reported as a sheet property and is not standardized with respect to thickness to give a material property per unit thickness.
Note 3 to entry: The Sheffield unit is not defined, since it has been shown that the scale units (Sheffield units) on different types of Sheffield instruments can correspond to different air flows, and there is no precise physical definition. This part of 150 5636 requires that the flowmeters be calibrated to give a flow rate in millilitres per minute.
4 Principle
A test piece is clamped between two rubber orifice plates of known dimensions. The absolute air pressure on one side of the test piece is equivalent to atmospheric pressure and the difference in pressure between the two sides of the piece is maintained at a small, substantially constant, value. The air flow rate through the test area is determined and the air permeance is calculated.
5 Apparatus
The Sheffield apparatus, see Figure 1 for an example of one type of instrument, shall consist of an air supply (see 5.1), an air-pressure regulating device (see 5.2), a pressure manometer (see 5.3), an air-flowmeasuring device (see 5.4) and a test assembly (see 5.5) which houses a measuring head in which the test piece can be securely clamped.
5.1 Air supply, free from water, oil and other contaminants, at a pressure of 420 kPa to 950 kPa. A small compressor using laboratory air is preferred to external compressed air.
5.2 Air-pressure regulating device, to reduce the pressure to the nominal pressure at the measuring head of 10,3 kPa (variable-area flow-measuring devices, see 5.4.1) or 9,85 kPa (electronic flow-measuring devices, see 5.4.2).
5.3 Pressure manometer, with a suitable range to enable the air pressure at the measuring head to be set to the specified pressure within 2 % of the nominal value.
5.4 Air-flow-measuring device, of either a variable-area (SAl) or an electronic type (5.4.2), for
measuring the air flow rate to the measuring head. The air flow rate shall be measurable to an accuracy of
± 5 % of the measured value.ISO 5636-4 pdf download.