Industrial filter cloth air permeability (air permeability) unit conversion and selection guide

Release time:

2025-03-19

Air permeability is a key performance indicator for industrial filter fabrics, but its unit varies by region, so it is necessary to pay attention to the conversion relationship between units when selecting. Air permeability and filtration accuracy cannot be directly converted and need to be comprehensively evaluated in conjunction with other parameters. In practical applications, it is recommended to prioritize operating conditions and sample experiments to select the most suitable filter fabric product.

Abstract:
The air permeability (air permeability rate) of industrial filter cloth is an important indicator for measuring its air permeability performance, directly affecting filtration efficiency and usage effect. Different countries and regions have different expressions for the units of air permeability. Common units include L/m²/s, L/dm²/min and cfm. This article will start from the perspective of practical application, combined with the practical experience of Xiamen Dias filtration technology, introduce the common units of air permeability and their conversion relationships, and discuss the relationship between air permeability and filtration accuracy to provide reference for the selection of filter cloth.

1. Definition and Importance of Air Permeability

Air permeability refers to the volume of gas passing through a unit area of filter cloth per unit time under a certain pressure difference. It is a key parameter for measuring the air permeability performance of filter cloth, directly affecting filtration efficiency and energy consumption. Excessive air permeability may lead to a decrease in filtration accuracy, while too low air permeability will increase filtration resistance and affect filtration speed. Therefore, reasonable selection of air permeability is an important link to ensure filtration effect.

2. Relationship between Air Permeability and Filtration Accuracy

It should be noted that, air permeability and filtration accuracy cannot be directly converted. Filtration accuracy is a comprehensive concept, usually characterized by the pore size, mesh number, etc., of the filter cloth. Air permeability, pore size and mesh number all belong to the scope of filtration accuracy, but there is no direct mathematical relationship between them. For example, filter cloth with high air permeability does not necessarily have low filtration accuracy, because air permeability is also affected by factors such as material thickness and fiber structure.
In actual selection, air permeability and filtration accuracy need to be considered comprehensively with other parameters (such as thickness, material, temperature resistance, acidity and alkalinity, etc.) to select the most suitable filter cloth for the working conditions.

3. Common Air Permeability Units and Conversion Relationships

Different countries and regions have different expressions for the units of air permeability. The following are three common units:
  1. Commonly used units in China: L/m²/s @ test pressure 200Pa, test area 20cm²
  2. Commonly used units in Europe: L/dm²/min (or dm/min) @ test pressure 200Pa, test area 20cm²
  3. Commonly used units in the United States: cfm (cubic feet/minute) @ test pressure 125Pa, test area 38cm²

Unit Conversion Relationships

The following are the conversion relationships between common air permeability units:
  • 1 L/m²/s = 0.6 L/dm²/min = 0.197 cfm
  • 1 L/dm²/min = 1.667 mm/s
  • 1 cm³/cm²/s = 10 mm/s
  • 1 m³/m²/min = 16.667 mm/s
  • 1 m³/m²/h = 1000.02 mm/s

Conversion Example

For example, the air permeability of a certain filter cloth is 100 L/dm²/min, converted to other units:
  • 100 L/dm²/min = 100 × 1.667 mm/s = 166.7 mm/s
  • 100 L/dm²/min = 100 / 0.6 L/m²/s ≈ 166.67 L/m²/s
  • 100 L/dm²/min = 100 / 0.197 cfm ≈ 507.61 cfm

4. Precautions for Air Permeability Selection

  1. Slight difference in air permeability: There may be a slight fluctuation in air permeability in actual tests, so the actual test data should be used as a reference during selection.
  2. Combined with working conditions: Different working conditions have different requirements for the air permeability of filter cloth. When selecting, the properties of the filtration medium, filtration pressure, temperature and other parameters should be considered comprehensively.
  3. Sample experiment: Before bulk purchase, it is recommended to verify whether the air permeability and other performances of the filter cloth meet the requirements through sample experiments.
  4. Other parameters: In addition to air permeability, the thickness, material, weight, breaking strength, temperature resistance, acidity and alkalinity of the filter cloth should also be considered to ensure that it is suitable for specific working conditions.

5. Practical Support of Xiamen Dias Filtration Technology

At Xiamen Dias, we are committed to providing customers with professional Powered by and solutions. Through advanced testing equipment and rich industry experience, we can help customers accurately measure the air permeability performance of filter cloth, and provide the optimal selection suggestions based on specific working conditions. Whether it is high-temperature flue gas filtration or corrosive medium filtration, we can ensure that the filter cloth performs optimally in practical applications through scientific analysis and experiments.

6. Summary

Air permeability is an important performance indicator of industrial filter cloth, but its units vary from region to region, and the conversion relationship between units should be noted during selection. Air permeability and filtration accuracy cannot be directly converted, and other parameters need to be comprehensively evaluated. In practical applications, it is recommended to use working conditions and sample experiments as the main criteria to select the most suitable filter cloth products.

By combining the practical experience of Xiamen Dias filtration technology, this article provides a practical reference for relevant professionals, helping them to better understand and apply this parameter of air permeability, and improve the efficiency and reliability of the filtration system.

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