GB1564872A - Asymmetrical filter for removal of suspended material - Google Patents

Abstract

The asymmetric filter for suspended matter is suspended in a frame (1) and is composed of a strip- or belt-like filter material (2) folded in a concertina manner; between each layer of the filter material (2) is arranged a folded or pleated film (3; 3') made of aluminium, card or plastic, in order to maintain the required spacing between the layers. This film, on the dust inlet side of the filter for suspended material, has a larger fold (3), in order to achieve a wider spacing between the layers of the filter material (2) than the film which is arranged on the clean gas side of the filter material. <IMAGE>

Description

(54) ASYMMETRICAL FILTER FOR REMOVAL OF SUSPENDED MATERIAL (71) I, KALMAN ANDRASFALVY, 139141 Hauptstrasse 7553 Muggensturm, Germany, a German National, do hereby declare the invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention concerns an asymmetrical filter for removing suspended or floating material, which can be inserted particularly in devices and systems for recovering powder, more particularly in systems for electro-static powder coating, or in general for the separation of powder and dust from a gaseous phase.

Known filters for suspended substances of the above-described type usually comprise a band or strip of filter material, for example, filter paper, or fibre glass material, which is pleated and inserted folded zig-zag fashion inside a box-shaped frame.

Between each resultant pleat of filter material, a folded or pleated foil is inserted alternately from one side or the other and ensures the necessary spacing between the individual pleats of filter medium.

In known filters for removing suspended substances these folded or pleated foils consist of aluminium, hard paper or p]astics material and have an identical fold both on the dust side and on the clean gas side.

The folded or pleated foils therefore serve as spacers, uniform spaces existing between the individual layers of the filter medium.

An object of the present invention is to improve known suspended substance filters with regard to increased filtration capacity and to make it possible to clean said filters.

In known filters in which the spacing is optimally calculated with reference to the intended air speed through the filter, it has become apparent, however, that the filter soon becomes clogged, due to the restriction of the cross-section caused by the build-up of separated particles.

The invention accordingly provides an asymmetrical filter for removal of suspended substances from gases, comprising a pleated strip or band of filter material disposed in a frame, having between each pair of adjacent legs of the pleats, to maintain the necessary spacing between the filter medium pleats, a folded or pleated gas impervious foil spacer characterised in that the bays between the pleats on the gas inlet side are wider than the bays between the folds on the gas outlet side, the spaces in the bays on the inlet side having deeper folds or pleats than the spacers in the bays on the gas outlet side.

According to a preferred embodiment, the ratio of the depth of the folds of the foil spacers on the dust inlet side relatively to the depth of the folds of the spacers on the clean gas outlet side ranges approximately from 2:1 to 3:1 according to the type of material to be filtered.

In order to allow for the greatest total area of material per filter body, since this area is also optimal for the given air speed through the filter, it is proposed, according to the present invention, to reduce the spacing of the legs of the pleats of filter material on the outlet side and to increase them on the dust inlet side. This achieves the very essential advantage that, in the case of filter ratios which are otherwise the same, a much greater dust storage capacity in the filter is made possible.

A filter for suspended material, according to the present invention is now described by way of example with reference to the accompanying drawings in which: - Fig. 1 is a partially exploded perspective view of a filter according to the invention; Fig. 2 is a magnified view of the dust inlet side of the filter according to the present invention; Fig. 3 is a magnified view of the outlet gas side of the filter according to the present invention.

Fig. 1 shows an asymmetrical filter according to the present invention which comprises an open sided box-shaned frame 1 in which a filter medium 2, folded concertinafashion, is inserted. The filter medium may consist for example of a filter paper, or a fibre glass material. Folded or pleated foils 3 and 31 are inserted between the individual pleats of filter medium 2 and these are pleated at right angles to the filter medium pleats to maintain the necessary spacing between the individual pleats of the filter medium 2.

The filter can then be inserted into a filtration apparatus, dust-containing air being blown from one side through the filter in the direction of the arrow 4 and flowing out again at the other side in the direction of the arrow 5. The dust or the recovered powder then collects between the pleats of the foils 3.

In the filter for removal of suspended substances according to the present invention, the foils 3 provided on the dust inlet side have a larger fold than the foils 31 on the clean gas outlet side. Thus the individual chambers on the dust inlet side are larger, and the spacing between the legs of the pleats of filter medium 2 is also enlarged. On the clean gas outlet side, as shown in Fig. 3, the spaces between the legs of the filter medium pleats are smaller, as may be seen from the smaller fold of the foils 31.

According to the type of material to be separated from the fluid stream, the ratio of the folds in the spacers on the inlet side to the folds in the spacers on the outlet side is from about 2:1 to 3:1.

WHAT I CLAIM IS: - 1. An asymmetrical filter for removal of suspended substances from gases, comprising a pleated strip or band of filter material disposed in a frame, having between each pair of adjacent "legs" of the pleats, to maintain the necessary spacing between the filter medium pleats, a folded or pleated gas impervious foil spacer characterised in that the bays between the folds on the gas inlet side are wider than the bays between the folds on the gas outlet side, the spacers in the bays on the inlet side having deeper folds or pleats than the spacers in the bays on the gas outlet side.

2. An asymmetrical filter for removal of suspended substances from gases according to Claim 1, characterised in that the ratio of the depth of the folds of the foil spacers on the gas inlet side to the depth of the folds of the foil spacers on the gas outlet side ranges from approximately 2:1 to 3:1 according to the nature of the material to be filtered.

3. An asymmetrical filter for removal of suspended substances from gases substantially as hereinbefore described with reference to the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (3)

**WARNING** start of CLMS field may overlap end of DESC **. fibre glass material. Folded or pleated foils 3 and 31 are inserted between the individual pleats of filter medium 2 and these are pleated at right angles to the filter medium pleats to maintain the necessary spacing between the individual pleats of the filter medium 2. The filter can then be inserted into a filtration apparatus, dust-containing air being blown from one side through the filter in the direction of the arrow 4 and flowing out again at the other side in the direction of the arrow 5. The dust or the recovered powder then collects between the pleats of the foils 3. In the filter for removal of suspended substances according to the present invention, the foils 3 provided on the dust inlet side have a larger fold than the foils 31 on the clean gas outlet side. Thus the individual chambers on the dust inlet side are larger, and the spacing between the legs of the pleats of filter medium 2 is also enlarged. On the clean gas outlet side, as shown in Fig. 3, the spaces between the legs of the filter medium pleats are smaller, as may be seen from the smaller fold of the foils 31. According to the type of material to be separated from the fluid stream, the ratio of the folds in the spacers on the inlet side to the folds in the spacers on the outlet side is from about 2:1 to 3:1. WHAT I CLAIM IS: -

1. An asymmetrical filter for removal of suspended substances from gases, comprising a pleated strip or band of filter material disposed in a frame, having between each pair of adjacent "legs" of the pleats, to maintain the necessary spacing between the filter medium pleats, a folded or pleated gas impervious foil spacer characterised in that the bays between the folds on the gas inlet side are wider than the bays between the folds on the gas outlet side, the spacers in the bays on the inlet side having deeper folds or pleats than the spacers in the bays on the gas outlet side.

2. An asymmetrical filter for removal of suspended substances from gases according to Claim 1, characterised in that the ratio of the depth of the folds of the foil spacers on the gas inlet side to the depth of the folds of the foil spacers on the gas outlet side ranges from approximately 2:1 to 3:1 according to the nature of the material to be filtered.

3. An asymmetrical filter for removal of suspended substances from gases substantially as hereinbefore described with reference to the accompanying drawings.