AIR PERMEANCE – Bekk
Purpose of the test
This test is performed to determine theair permeance of paper according to Bekk.
Procedure
Operate the instrument in accordance with the manufacturer’s instructions.
Leave the samples exposed for 24 h to 23°C and 50% R.H., according to ISO 187.
Insert a rubber gasket with an outer diameter of 45 mm and an inner diameter of 12 mm between the glass plate and test piece (adjust co-axially)
Measurements are to be taken in the middle of each test piece with the marked side turned towards the air flow.
Therefore, produce a vacuum of more than 50.66 kPa (= 380 mmHg) in the vacuum container and measure the time required, in seconds, for the air pressure in the vacuum container to drop from 50.66 kPa (= 380 mmHg) to 29.33 kPa (= 220 mmHg).
Report 10 measures in s, their mean and standard deviation calculated to 3 significant figures.
---
Nr. of samples
12 test pieces per level
Speciasl size A4
Levels
Level 1: 4.00÷10.0 s
Level 2: 10.0÷15.0 s
Level 3: 40.0÷90 s
Level 4: 170÷230 s
Reporting
Report 10 valid results of measurements in s, their mean and their standard deviation. All to three significant digits.