The gas mask is a PPE commonly used in toxic operations, and the cartridge can filter out harmful vapors or vapors in the air, or reduce their concentration to protect the health of the user.

How does the gas filter work?

In order to make the filter box more selective for some chemical substances, after impregnating the activated carbon with chemical reagents, some special chemical substances can chemically react with the reagents on the activated carbon, and this adsorption is also called chemical adsorption.

Chemisorption force is a chemical binding force, much stronger than the simple physical adsorption force, and irreversible, such cartridge in use as long as attention does not occur penetration, timely replacement of organic vapor filter box, often there will be no occupational hazards such as poisoning.

Penetration refers to the saturation of activated carbon adsorption, which has lost its filtering function. If not replaced, harmful vapors will be directly inhaled by the user. But for organic vapor filter cartridges, the situation is quite complicated. Firstly, there are various types of organic vapors, and the same organic vapor filter cartridge has different adsorption capacities for different substances, making it difficult to determine the replacement time uniformly. Another prominent issue is that due to weak physical adsorption forces, the adsorption process may reverse and result in resolution.

Classification of Organic Vapor Types :

For organic vapor filter cartridges, during the period of discontinuation, even if there is no airflow movement inside the cartridge, the originally adsorbed substances will still be resolved. The resolved substances will diffuse backwards from the carbon layer at the inlet end of the cartridge until they diffuse throughout the cartridge. This phenomenon is called migration, and the factors that cause migration include:

1.  The volatility of the adsorbed substance, the stronger the volatility, the easier it is to migrate;

2.  If the environmental humidity is greater than 50%, migration is more likely to occur;

3.  The original adsorption capacity of the filter cartridge;

4.  Storage time of filter box;

5.  Types of steam.

Precautions for using the gas filter:

1. For stable operations, based on existing usage experience, and taking into account the types and concentration levels of pollutants at the work site, work intensity, temperature, humidity, and volatility of substances, a schedule for replacing filter cartridges should be established and executed accordingly. If the manufacturer of the filter cartridge can provide recommendations on the service life of the filter cartridge based on on-site parameters, it would be helpful.

       2. If the boiling point of the adsorbed substance is lower than 65℃;  It is recommended to replace the organic vapor filter cartridge daily.

    3. If it is believed that the adsorbed substance is prone to volatilization and the filter cartridge is stopped for a few days during use, such as during weekends, it is recommended to replace the organic vapor filter cartridge.

       4. Even if it is believed that the adsorbed organic substances are not easily volatile, if the filter cartridge is stopped for about two weeks during use, it is recommended to replace the organic vapor filter cartridge.