Fabric Air Permeability Digital Meter Testing Experience

The digital fabric air permeability meter is used to measure the air permeability of various materials such as textiles, garments and non-woven fabrics. Qisnun Precision Electromechanical Technology Co., Ltd. is a manufacturer. Welcome customers who need to inquire.

Test standard:

GB/T 5453-1997, GB/T 13764, ASTM D737, ISO 9237, ISO 5636

Permeability to fabric air refers to the fabric The performance of the fabric in the air when there is a pressure difference between the two sides. That is, under the specified pressure difference on both sides of the fabric, the volume of air passing through the unit area of ​​the fabric per unit time, the unit is L/mm2s. Since pressure difference is a necessary condition for air to flow, only when a certain pressure difference is maintained on both sides of the fabric under test can air flow be generated in it.s the fabric.

Test method:

The air permeability requirements of different fabrics are very different, even the same fabric, due to use For different requirements, the pressure difference between the two sides of the fabric is often different. Therefore, different pressure drops should be selected for testing depending on the characteristics of the fabric itself and the usage requirements.

The test method is to pass the gas through the fabric already in place under a certain pressure difference, and test the air flow, to obtain the air permeability fabric. Most clothing fabrics can be considered relatively sparse and the pressure requirements for testing are relatively low. At this low pressure level, it is customary to use a vacuum pump to pump air to achieve the pressure difference requise and read the gas flow from the flowmeter.

The key technology of the digital tissue air permeability meter is the measurement of pressure and flow. Our instrument uses an orifice flow meter to measure airflow, and a U-shaped tube to measure atmospheric pressure. The orifice plate has been used as a flowmeter device for over a hundred years, and many national and international standards are promulgated with it as the head. In narrow pipes, the orifice plate is used as a blocking plate for measurement and forces the flowing material to be pressed. When the filled fluid of the pipe flows through the constriction part into the pipe, the flow bundle will form a local contraction at the constriction part and the static pressure will decrease, so that a difference of pressure will be generated before and after the throttling part, and the higher the fluid flow, plus the pressure difference generated is large, so the flow rate can be measured according to the pressure difference. The use of orifice flow meters is common in many installations. There are also tissue air permeability testing instruments that use Venturi tubes to measure flow. Compared with the orifice plate, the pressure drop of the Venturi tube is small and its service life is long.

Whether it is an orifice throttling device or a Venturi tube throttling device, the measurement method is based on the flow continuity equation ( law of conservation of mass) and Bernoulli\'s equation (law of conservation of energy), Suitable for measuring constant airflow. The following conditions must be met when using a standard throttling device for flow measurement:

(1) The measured fluid fills the entire section of the pipe andflows along a circular pipe with an inside diameter of at least 50 mm; for the Venturi tube, its pipe diameter should not be less than 100mm or more than 800mm.

(2) The flow in the pipeline is stable, or can actually be said to be stable (when the flow is stable, the flow velocity and the pressure at the same point do not change with time)

(3) When the measured medium passes through the throttling device, its phase state remains unchanged (for example: the liquid does not evaporate, the superheated vapor is still superheated, the gas dissolved in the liquid does not precipitate, etc.), and it exists in a single phase of. Media with complex compositions should only be used if their properties are similar to those of single-component media.

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