The dust classes L, M and H differentiate the permissible dust concentration after filtering, which depends on the size of the dust particles, their general nature and the structure of the filter medium. A further distinction is made directly and indirectly according to the risk potential. To put it simply:
House dust, sand, crumbs, scraps, etc. are classified under dust class L. Gypsum and lime, provided they have not been mechanically processed
are also included here, among other things because they do not have any special disposal requirements.
In dust class M we find wood dust, paint particles, various metal dusts and dusts which, for example, after mechanical processing, i.e. by grinding, drilling, milling or sawing have particle sizes in the nano range. Due to the particle size and composition, there is already a medium health risk potential and higher demands are placed on the vacuum cleaners, filters and bags used.
Because, just as these dusts endanger our respiratory tract, their nano particles also clog the pores of conventional filter materials
with the result that the vacuum cleaner loses power due to clogged filters, the vacuum cleaner's motor is overstressed and the vacuum cleaner bag can burst.
At the latest, the greatest care must be taken with dust class H, because this is where dusts that are highly hazardous to health are classified, e.g. carcinogenic substances such as asbestos, mold spores, lead dust and various types of mineral fibers.
The following note on easily flammable or even explosive dusts is also absolutely necessary. As an example, I would like to mention
Petrol fumes in the vacuum cleaner or similar. The static charge that develops in the vacuum cleaner hose due to the friction of dust particles can cause sparks with devastating consequences.
Finally, here are a few practical tips for hobby craftsmen, but also for professionals from our 16 years of experience as a dealer of vacuum cleaner accessories.
Before using, make sure you check the operating instructions for your vacuum cleaner to see which dust classes it is generally suitable for.
Drilling, grinding and milling always produce dust particles in the nano range, regardless of the material being processed, which are difficult to deal with with household vacuum cleaners, but also with many hobby devices.
Dust class M is therefore the minimum requirement without any ifs and buts. We therefore only recommend vacuum cleaners that meet this requirement. In order to save costs, these devices can also be used for conventional applications, and suitable filters and bags of dust class L are also sufficient.
For large amounts of grinding dust, such as when working with grinding giraffes or concrete milling machines, we only recommend devices with vibration technology.
The standard determines the classification according to the MAK values, i.e. the dust concentration in milligrams per cubic meter (mg/m3) Using the example of dust class L, you can see that the Dust retention of the filter medium, i.e. the vacuum cleaner bag or filter must be at least 99%. One percent therefore passes through the filter or clogs the pores of the filter material if the particle sizes of the vacuumed material are large numbers of smaller or equal to the pores of the bag. In the case of the dust bag, this results in it giving way at the weakest point, usually at the seam or the attachment to the suction nozzle. It becomes more critical with the filter, because the air becomes thinner there, which puts a great deal of strain on the motor. You can hear it, because the engine starts to "howl" and the operating noise shifts upwards in terms of sound pressure level and frequency.
The dust class M places 10 times higher demands on the filter material, because only 0.1% permeability is permitted here, so bags and filters must have a considerably finer structure. And so even nano-particle sizes in suction materials are left behind.
Suitable for dry, hazardous, non-flammable dusts Since 01.01.2005 | Applicable dust classes according to DIN EN 60335-2-69, Annex AA | ||
Dust Clss | Maximum Transmittance | ||
with AGW > 1 mg/m3 | At least L (M,H) | < 1 % | |
with AGW ≥ 0,1 mg/m3 | At least M (H) | < 0,1 % | |
− with AGW < 0,1 mg/m³ − carcinogenic hazardous substances acc. GefStoffV § 11, TRGS 905 bzw. TRGS 906 | H | < 0,005 % | |
H | < 0,005 % | ||
Asbestos gem. TRGS 519 | H + Suitability for Use according to TRGS 519 | < 0,005 % | |
Additional suitability for combustible dusts of all dust explosion classes (except dusts with extremely low minimum ignition energy ME < 1 mJ) | At least L With additional testing according to DIN EN 60335-2-69, Anhang CC Devices of the type Zone 22 |