Composite Sub-High Filter with 220 Initial Resistance and F9 efficiency rating.

The activated carbon medium for acidic gas removal consists of chemically modified carbon, suitable for acidic and corrosive environments. It effectively removes about 90% of pollutant gases, including:

• Sulfuric acid
• Sulfur dioxide
• Volatile organic compounds (VOCs)

The activated carbon medium for alkaline gas removal effectively eliminates ammonia gas, removing about 90% of pollutant gases. The filter medium reacts with pollutant gases to form inorganic salts, which are not easily resolved. The adsorption reaction mechanism is immediate, safe, and permanent.

In the air filtration industry, there are numerous standards for classifying, identifying, and evaluating the various performance characteristics of air filters.

Since 1968, ASHRAE has released a series of test standards for air filters, which have been recognized by the American National Standards Institute (ANSI) as the benchmark for filter performance classification.

In Europe, reference was made to ASHRAE standards, and CEN formally released the European filter standard EN 779 in 2012. The 2012 revision defined the minimum filtration efficiency (ME) for F7-F9 efficiency filters, ensuring better air quality at the AHU outlet.

EUROVENT developed the "Eurovent 4/11" guidelines in 2012 (upgraded in 2015) based on the EN 779:2012 standard for energy consumption calculation and classification. This enables selection of high-efficiency filters with lower energy consumption.

Introduced in 2016, the ISO 16890 standard provides global standardization in the air filtration industry, replacing the existing regional standards ASHRAE 52.2 and EN779:2012.