DE1020238B - Process for the production of filter material webs for HEPA filters and filters produced by this process - Google Patents

Description

GERMAN

The invention relates to a method of manufacture of filter material webs for HEPA filters, where the od from air-permeable paper, cardboard. The like. Existing Filter layer is laid in folds.

With every HEPA filter, efforts are made to ensure that the filter has the highest possible interception capacity To keep breathing resistance as low as possible For this reason it is necessary to use the filter material to give a large surface. If there is only a limited space available in the filter housing, then it is necessary to provide very tight folds. With such filters it can happen that In particular, when breathing heavily, such a congestion occurs that the flanks of the folds are compressed and the passage of air is blocked because the surfaces of the filter material lie close to one another. With such filters there is also an increased risk of clogging if the inhaled Air contains dust or smoke.

To avoid this inconvenience, it has already been proposed to use aids which to prevent the tight overlapping of the fold flanks. So one has z. B. tried comb-like Push the spacers into the folds. This creates friction that affects the filter paper is worn through after a long period of use, so that the filtering effect suffers.

In the case of other types of suspended matter filters, e.g. B. the well-known chamber filters, which consist of individual rings Flat filter material are composed, one also has radial groove-like depressions in the filter surfaces pressed in, so that radial elevations arise on the other side, which the laying together the approaching filter surfaces.

By pressing such depressions into the filter material, there is the disadvantage that the The homogeneity of the filter material is damaged by the fact that the filter surface is compacted in different places and that the optimal structure is disturbed by fiber strains and thereby the performance of suspended matter is reduced. Pressing in the indentations also increases the filter resistance.

In contrast, the invention consists in the fact that the filter material web intended for folding is already at their production with small elevations, forms or the like. Is provided, so that the flanks of the The folds of the filter folded out of the web are only point-shaped or linear, even if they are tightly folded touch. In the event that the elevations are made like grooves, the grooves are recommended to run in irregularly curved lines. The deformation of the wrinkle fabric happens z. B. in that the still moist fiber material

of filter cloth webs for

HEPA filter and after this

Process manufactured filter

Applicant:

Auergesellschaft Aktiengesellschaft,
Berlin N 65, Friedrich-Krause-Ufer 24

Dr. Walter Lemcke, Berlin-Reinickendorf West,
has been named as the inventor

runs through rollers during the couching process, which give the filter material the desired surface design. In this way, the uniform fiber structure remains in contrast to the earlier press-fit of the grooves in the finished filter fabric.

The drawing shows two exemplary embodiments of the invention. In

Fig. 1 is a diagram of a piece of a HEPA filter paper 1 is shown with the indented elevations and recesses 2 are provided; the

Fig. 2 shows a filter paper, in which the elevations and depressions 3 in irregularly curved Lines run; the

Fig. 3 shows a section of a folded particulate filter in which the folded paper is designed according to Fig. 2.

It can be seen from the illustration that the flanks of the folds never lie completely against one another, even if they are tightly folded can.

Claims (2)

Patent claims: 1. Process for the production of filter material webs for HEPA filters, in which the air-permeable paper, cardboard or the like. Existing filter layer is placed in folds, thereby characterized in that the filter material web intended for folding is already included in its manufacture small elevations (2), ribs (3) or the like. 709 807/39 will see so that the flanks of the pleats of the filter folded from the web when folded tightly only touch them in dots or as a dashed line. 2. Prepared by the method of claim 1 HEPA filter, characterized by net that the ribs (3) are curved lines. in irregular Documents considered: French Patent Nos. 745 466, 841 549. 1 sheet of drawings