EXPERT KNOWLEDGE WET AND DRY EXTRACTORS

In a woodworking shop, the ability to vacuum dust is extremely important and essential for a clean work result and a good service life of tools such as milling cutters or Abrasive paper sandpaper. Wet and dry extractors designed for fine dust are also particularly important for your own health.

Wet and dry extractors are mobile vacuum cleaners that can be used not only to vacuum machines, but also to pick up liquids from the floor. Many mobile vacuum cleaners can do both, although in most cases a different filter must be used. In commercial cleaning, large wet/dry extractors (e.g. machines from Kärcher) are often used to remove water or a water/cleaner mixture from large areas after cleaning. In the trade, the main focus of a wet vacuum cleaner is to avoid the need for an extra vacuum cleaner in addition to a dry vacuum cleaner in the event of liquid spillages or cleaning work. Important areas of application for pure wet vacuum cleaners are more likely to be found in the renovation or cleaning sector.

What does a wet/dry vacuum cleaner need to do?

A mobile extraction unit should be able to suck up the resulting sanding dust or sanding swarf with as little loss as possible by connecting it to an extraction hose. There are major differences between the various machines in terms of extraction performance and the volume of the filter bag. Of course, the Type of dirt to be removed is also decisive. There are machines that can be extracted very well with mobile extractors, e.g. electric sanders for sanding wooden surfaces (random orbital sanders, Delta sanders ...). As sanding dust is very fine and light, it is ideal to work with an extraction unit. The extracted dust largely disappears from the surface to be sanded, preventing the Abrasive paper sandpaper from sticking and improving not only the service life but also the surface quality.

This is similar for Portable circular saws. As the connection for the extraction system on a Portable circular saw is positioned in such a way that the chips are extracted in the direction of flight, the extraction unit does not require a particularly strong suction power. With this machine too, dust and chip extraction not only ensures cleaner ambient air, it also benefits the service life of the saw blade and the quality of the kerf.

However, there are also uses where the suction power of a mobile dust extractor is sometimes not sufficient. If an edge is to be routed with a router and the router does not have an additional housing to support the extraction, it is difficult to guarantee good extraction performance.

It should always be possible to switch quickly between wet and dry suction. On Festool and Mafell mobile vacuum cleaners, the filter bags are removed and the main filters are replaced with sponge filters at the click of a button. The vacuum cleaners also have sensors that shut down the vacuum cleaner at a certain maximum fill level, thus protecting the electronics.

The vacuum cleaners are usually equipped with a socket to which the appliance to be vacuumed can be connected directly. The hoover then starts automatically when the machine is switched on.

Manufacturer designations and what they mean

The manufacturer's labelling already provides important information about the respective extraction devices. Two of the most important details and decision criteria for most users are the Dust class* or the filter permeability and the container volume.

AnL stands for the Dust classLightHazard, anM for the Dust classMediumHazard, anH for the DustclassHighHazard. Numbers such as 25 stand for the container volume of 25 litres.

The new generation of Festool mobile dust extractors, which can be securely attached to the power tool by means of fixed sleeves, is called CLEANTEC, the abbreviation is CT.

Categorisation of Dust classes

Dust class L

For simple and slightly hazardous dusts such as house dust, sand, earth, lime, plaster. The filters have a maximum permeability of 1 mg/m³. Can also be used for wood dust in the private sector.

Dust class M

For harmful wood dusts and dusts from Palette knives, fillers and varnish, cement, concrete and Colours. The filters have a maximum permeability of < 0.1 mg/m³. Low-dust disposal is guaranteed.

Dust class H

For carcinogenic dusts such as asbestos dust and dusts contaminated with pathogens (e.g. mould, bacteria, viruses). The filters have a maximum permeability of 0.005 % with a limit value of ≤ 0.1 mg/m³. Low-dust disposal is guaranteed.

There are different Dust classes for different uses and types of dust. Different regulations apply for use in a commercial environment than for use in a hobby workshop or the basement at home. Private users do not have to observe any regulations here, but you should also pay attention to your own health in the case of hazardous dusts, as wood dusts, dusts from Palette knives, fillers and paint are considered hazardous to health. With some types of wood, the dusts are also suspected of having a carcinogenic effect.

Dust class L is recommended for vacuuming slightly hazardous dusts and coarser particles (e.g. house dust, soil).

Dust class M must be used in the commercial sector for vacuuming dusts that are hazardous to health, including wood dust.

For carcinogenic dusts such as asbestos dust and dusts contaminated with mould, a Dust class H extraction unit must be used.

Another important decision criterion is the suction power

The suction power is specified as the max. volume flow. You can use this value to compare different models. However, the actual suction power depends on several factors.

• Which machine is being extracted (a high proportion of external air minimises the extraction performance)
• What is being extracted (coarse chips or fine dust, wet or dry material)
• Fill level of the container or chip bag
• Diameter and Length of the Suction hose
• Size of the Filter surface area and condition of the filter (clogged filter pores minimise performance)

Wet and dry extractors accessories

Mobile vacuum cleaners do not usually come with additional accessories such as a floor nozzle or crevice nozzle as part of the scope of delivery. However, there is an extensive range that extends the functions to include cleaning floors, such as vacuuming dry dirt, chips or dust.

Floor nozzle and extension tube

The floor nozzle and extension tube are always included in the Scope of delivery of conventional domestic hoovers. However, cleaning or vacuuming floor surfaces is of secondary importance with mobile vacuum cleaners. These accessories are therefore rarely included in the basic equipment, but are available from most manufacturers as optional accessories.

Crevice nozzle and suction brush

Crevice nozzles and suction brushes are practical helpers for cleaning during assembly work or in the workshop. The fine brushes help to pick up dirt and dust with virtually no residue. For example, they prevent the suction hose from scratching a finished, sanded surface before the next surface treatment.

These accessories are also often offered in practical sets that contain all the necessary components for extraction work as well as cleaning and removing dirt or liquids with the mobile extractor or wet and dry extractor.