The Shober method Paper Air Permeance Tester is designed and manufactured according to the industry standard of the People's Republic of CHINA QB/T1667 "Paper Permeability (Shawber Method) Tester".
Many kinds of paper, such as cement bag paper, paper bag paper, cable paper, copy paper and industrial filter paper, etc., need to measure the degree of air permeability, and this instrument is designed and manufactured for the above various papers. This instrument is suitable for air permeability in the range of 1×10ˉ²—1×10²μm/(Pa· S), not suitable for paper with a large surface roughness.
The instrument is composed of a container (12) on a fixed pillar (2), a paper pattern clamp ring (4) and a pressure gauge (6) and the like. The upper part of the container is equipped with a breathable valve (13) and a water filling valve (1) with a funnel, and distilled water is injected into the container from a water filling valve with a funnel. The bottom of the container is equipped with an overflow valve (11) and a regulating valve (10) for controlling the flow of water. The paper pattern clamp ring is fixed on the support (3), and there is a hole with an area of 10 cm² on the paper pattern clamp ring and the air box (5). The air box is located below the paper pattern clamp ring, and there are two joints on it, which are connected with the exhaust pipe and the pressure gauge respectively with a rubber hose, and the base (9) under the instrumentFor the basis of the whole instrument, a level (7) is installed on it, and two adjusting bolts (8) are rotated to adjust the horizontal position of the instrument.
The working principle of this instrument: that is, the average air flow rate of paper per unit area under the specified conditions, under the unit time and unit pressure difference.
Close the overflow valve and the regulating valve, open the water filling valve and the ventilation valve, fill the container with distilled water from the water addition valve with a funnel, close the water filling valve and the ventilation valve, clamp the sample between the paper pattern clamping ring and the air box, place the measuring cylinder below the overflow port, open the overflow valve, and rotate the adjusting valve, adjust the pressure difference in the test area to 1kPa (100 mm water column), if the purpose cannot be achieved, the locking bolt can be loosened to lift the overflow pipe until the pressure difference in the test area is 1kPa, after stabilization, start the stopwatch to extract the quantity of water in the measuring cylinder for 1 minute, or 100 in the measuring cylinder The time it takes to mL of water.
Since the air permeability of the paper is well proportional to the constant differential pressure and the measurement time, other differential pressure and measurement time can be selected if necessary, but this should be noted in the report.Before the test, refer to Table 1 to select the appropriate test duration required to determine the air permeability. When selecting different test durations, the reading error of the test results should not exceed 2.5%.
| The air flow rate is ml/s | Test duration S | The volume ml was measured |
| 0.13-0.33 | 300 | 40-100 |
| 0.33-0.83 | 120 | 40-100 |
| 0.83-1.67 | 60 | 50-100 |
| 1.67-5.0 | 120 | 200-600 |
| 5.0-10.0 | 60 | 300-600 |
| 10.0-20.0 | 30 | 300-600 |
| 20.0-40.0 | 15 | 300-600 |
Table 1 When the constant differential pressure is 1 kPa