Gas and Combination Filters

Respiratory protective filters are classified according EN 14387:2008 or EN 14387:2021, EN 143:2007 or EN 143:2021, GOST 12.4.235-2013, and marked with the filter type (code letter and code colour) and filter class (code number) and standard. The filter type, filter class and referenced standard are marked on each filter.

Filter type	Colour	Application
A	brown	Vapours from organic compounds with a boiling point higher than 65 °C
B	grey	Inorganic gases and vapours, e.g. chlorine, hydrogen sulphide, hydrogen cyanide
E	yellow	Sulphur dioxide, hydrogen chloride, acid gases
K	green	Ammonia and derivatives of ammonia
P	white	Against particles of hazardous materials with a negligible vapour pressure

For the gas filters A, B, E and K, the filter class to be used depends on the possible maximum concentration of the hazardous gas and the required service time.

The classification, which is determined by the minimum breakthrough time of gas filters or gas filter part of a combination filter in laboratory tests under specified conditions, does not give any indication of the possible service time in practical use. Depending on the conditions of use, possible service times can deviate positively or negatively in both directions from the breakthrough times determined according to the present document. The classification of a filter does not reflect actual usage performance in the workplace and does not relate to any established workplace exposure limits.

Filter classes (code number)	EN 14387, GOST 12.4.235-2013	EN 14387:2021
class 1	1000 ppm (0.1 % vol.)
class 2	5000 ppm (0.5 % vol.)
class 3	10000 ppm (1.0% vol.)	5000 ppm (0.5 % vol.)

Important notice: In any case applicable National Regulations must be observed, especially to determine maximum allowable concentrations of toxic gases when using filters in conjunction with half or full face masks. Always the lowest concentration applies.

In Germany, the following applies: When using filters with half masks, the maximum 30-fold limit value applies as the limit of use, and in conjunction with full-face masks, the maximum 400-fold limit value applies as the limit of use. In any case, the limit values for filter classes 1 to 3 must not be exceeded.