TQD-01 Air Permeance Tester is used to determine the air permeance of paper and board in the medium air permeance range using the Schopper method. 

The method is applicable to papers and boards having air permeances between1×10-2~1×10²um/（Pa.S）. The method is unsuitable for rough-surfaced papers and boards, such as creped and corrugated papers, which cannot be securely clamped to avoid leakage.

TQD-01 Air Permeance Tester can also be used for other materials such as Cement bag paper, paper bag paper, cable paper, copy paper, industrial filter paper, etc.

The mean flow of air through the unit area under unit pressure difference in unit time, under specified conditions. 

It is expressed in micrometres per pascal second [1 μm/ (Pa·s)=1mL/(m²·Pa·s)].

Clamping a test piece between two airtight circular gaskets of known dimensions, with the absolute air pressure on one side of the test area of the test piece equivalent to atmospheric pressure and the difference in pressure between the two sides of the test piece maintained at a small but substantially constant value during the test. Determination of the flow of air through the test area in a specified time.

ISO 5636-2, ISO 5636-3, ISO 5636-5, GB/T 458, QB/ 1667