The time-tested AL-KO OPTI JET® method is the optimum combination of surface filtration and jet cleaning. The method offers considerable benefits compared to conventional three dimensional deep filters with vibration cleaning. The two-component principle allows the residual dust content to be kept permanently below 0.2mg/m³.

The advantage of surface filtration as the first work step is that chippings and dust are removed from the surface of the filter material, so that particles cannot ingress into the filter medium. During the extraction process, a filter cake forms on the outside of the filter hoses. With conventional filter media, the cake acts as an additional filter layer.

During jet cleaning, the second component of the AL-KO OPTI JET® process, the filters are cleaned by a surge of compressed air which penetrates the filter material from the inside to the outside. This type of cleaning uses the so-called festoon effect, i.e. the juxtaposing of the filter hoses around the vertical rods of the supporting baskets. The abrupt inflation of the filter hoses causes cracking and removal of the filter cake. The centrifugal movement followed by the stopping process results in the fine dust being ejected from the filter medium by forces of inertia.

The same effect is achieved by the so-called counterflush process: a jet of compressed air surges through the filter hoses against the filtering direction, so that the jet removes fine dust from the surface.

Jet cleaning constitutes the crucial difference to conventional filter cleaning, i.e. cleaning by mechanical vibration. The latter cracks the filter cakes by shaking the filter hoses. However, the vibrations cause the fine dust to ingress into the filter medium, so that the pores of the latter become clogged. Another drawback of this cleaning method is the high mechanical stress acting on the filter casing.

During jet cleaning the filter is inflated for a period of 0.8seconds, with only one-seventh of the consumed air being supplied by the compressor, whilst six-sevenths are ambient air which is drawn in by the jet of compressed air. This means that a small compressor is adequate to provide optimum cleaning results. An additional advantage is that the filter is cleaned automatically during operation, so that unproductive work interruptions are a thing of the past.

To prevent the maximum permissible residual dust content from being exceeded, conventional filter materials need an auxiliary filter layer. A completely cleaned deep-bed filter thus results in an additional dust load until it has again been covered with the required layer of dust. The AL-KO filter medium does not need this auxiliary layer, so that cleaning intervals can be freely selected.

Immediately after the cleaning process, the filter is fully operational again. On the one hand, due to its high weight per unit area of 500g/m², the filter material is extremely stable under load, and on the other hand, it is distinguished by its excellent air permeability and minimum dust permeability. The polyester needled felt of which the filter hoses are made is surrounded by a water- and oil-resistant layer, which allows every filter bag to be regenerated up to three times by washing.