Good to know
TYPES AND CLASSES OF GAS FILTERS
MARKING OF GAS FILTERS
Gas filter cartridges are typically marked using a combination of letters and numbers, e.g. “A2B2E1”.
The letters stand for the filter type. The filter type indicates which hazardous substances the gas filter protects against.
The numbers stand for the filter class, which gives information about the filters absorption capacity. In each case, the filter class applies for the filter type indicated by the letter directly preceding it. Filters in higher protection classes can be used to protect against higher concentrations of gas in the workplace.
As you can see from the example A2B2E1, a filter cartridge can be made up of several filter types (A, B and E), with the same or different levels of filter class. The filter in the example offers combined protection against organic gases (boiling point > 65° C), inorganic gases and acid gases.
FILTER TYPES
Colour code: Brown
Protects against: organic gases and vapours (boiling point > 65°C)
Colour code: Grey
Protects against: inorganic gases and vapours, e.g. chlorine and hydrogen cyanide (prussic acid); however, not against carbon monoxide
Colour code: yellow
Protects against: sulphur dioxide, hydrogen chloride and other acid gases
Colour code: green
Protects against: ammonia and organic ammonia derivatives
Colour code: brown
Protects against: low-boiling organic compounds (boiling point ≤ 65 °C) in low-boiling groups 1 and 2
Important: usage limitations for low boiling groups 1 + 2 (see DGUV Rules 112-190; filters are single use)
Colour code: red/white
Protects against: mercury
Note: The maximum period of use against mercury is 50 hours
FILTER CLASSES
Max. permitted concentration when using a half mask:
1000 ppm, but no more than 10 times the workplace exposure limit (WEL)
Max. permitted concentration when using a full face mask:
1000 ppm, but no more than 20 times the workplace exposure limit (WEL)
Max. permitted concentration when using a half mask:
5000 ppm, but no more than 10 times the workplace exposure limit (WEL)
Max. permitted concentration when using a full face mask:
5000 ppm, but no more than 20 times the workplace exposure limit (WEL)
Max. permitted concentration when using a half mask:
10000 ppm, but no more than 10 times the workplace exposure limit (WEL)
Max. permitted concentration when using a full face mask:
10000 ppm, but no more than 20 times the workplace exposure limit (WEL)
Disclaimer
This information is not legally binding and does not replace personal advice. Please note our terms of use.
