GB2383003A

GB2383003A - Filtration apparatus for the removal of particles from a gas

Info

Publication number: GB2383003A
Application number: GB0130087A
Authority: GB
Inventors: Jonathan Hugh Lambert Copus
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-12-15
Filing date: 2001-12-15
Publication date: 2003-06-18
Also published as: GB0130087D0

Abstract

An apparatus for removing solid particles from gases comprises a porous filter 4 whose rotation provides the motive force for drawing the gas through itself. The porous filter 4 may consist of a solid or hollow cylinder of plastic foam, mounted concentrically on the shaft of a drill bit (2, Fig 1) or the shaft of a motor 5 so that during rotation, the filter 4 rotates with, but not necessarily at the same speed as the shaft. During rotation centrifugal forces cause gas such as air to be drawn into the filter axis and ejected from the filter periphery causing solid particles suspended in the incoming air to be trapped in the foam. A casing 7 with inlet slots 8 and outlet slots 9 or an inlet duct (14, Fig 3) may be provided. Advantageously the apparatus is suited to the practice of chiropody or podiatry, air-conditioning systems and treating exhaust gases from factories or laboratories.

Description

FILTRATION OF GASES CONTAMINATED WITH SOLID PARTICULATES The removal of solid particles from a body of gas, including the atmosphere, is a common requirement in many industrial, medical and domestic situations. The present invention provides a way of removing such particulate contamination by means of a filter whose rotation provides the motive force to draw the gas through itself. This method has several advantages over traditional means of filtration in certain circumstances.

One application to which the present invention particularly but not exclusively relates arises in the practice of chiropody or podiatry, where practitioners frequently use handheld rotary drills to abrade patients'nails, which are often infected. Such drills usually rotate at between 10,000 and 50,000 revolutions per minute, and the result is that a fine mist of possibly infected nail dust is sprayed into the surrounding atmosphere, representing a severe health hazard.

Traditional solutions to this problem include removing the dust by a vacuum system: but this method has the disadvantage that it requires a suction pipe of relatively large diameter to be attached to the drill hand-piece, making the apparatus more cumbersome in use.

Another common solution is to apply a fine spray of water to the area around the tip of the drill bit or burr: this spray causes the nail dust to coagulate, but since the resulting aqueous suspension of detritus is not easily confined or collected it can also represent a significant risk to health.

The present invention overcomes these difficulties by using a porous filter mounted on the shaft of the drill bit or burr and concentrically with it in such a way that it rotates

with it, normally but not necessarily at approximately the same speed. The porous filter may characteristically consist of a solid or hollow cylinder of plastic foam whose diameter may typically be greater than its height to form a disc. When this disc rotates, centrifugal force causes air to be ejected from its periphery and drawn into the foam along its axis. Solid particles suspended in the incoming air are trapped in the foam. The material and the density of the foam and the dimensions of the disc may be designed to suit differing rotational speeds and circumstances, including different sizes of particles which it is desired to trap. When the foam becomes clogged it may either be cleaned and reused or else discarded. In medical applications the cheapness of the material makes single use and safe disposal of the device a realistic and attractive option.

A similar arrangement may be applied to drill bits used by carpenters, builders, do-ityourself enthusiasts and the like as a means of collecting and trapping the finer particles produced by the drilling operation.

In domestic and industrial air-filtering applications a filter of suitable composition and dimensions may be mounted directly on the shaft of a motor, eliminating the need for a separate impeller to move the air or other gas. Such impellers can often introduce variations of pressure into air-conditioning systems which are manifested as lowfrequency sound or infrasound, causing discomfort to the occupants of the building or room in which they are installed ; whereas the greater homogeneity of the filter in the present invention does not produce these effects.

One particular application is shown in Figure 1, in which a solid foam cylindrical disc (1) is mounted concentrically on the shaft of a rotating drill or burr (2) turned by a drill motor or hand-piece (3). Solid arrows indicate the flow of contaminated air and outline arrows show the ejection of filtered air by centrifugal force.

Another typical application is illustrated in Figure 2, where a portable air filter consists of a solid foam cylindrical disc (4) mounted on the shaft (5) of a motor (6). A cylindrical case (7) with inlet slots cut into its top (8) and outlet slots around its periphery (9) separates the contaminated air (whose direction of flow is shown by solid arrows) from the clean air (shown by outline arrows) ejected by centrifugal force.

Another typical application particularly suited to air-conditioning systems or the removal of noxious substances from the exhaust gases of factories or laboratories is shown in Figure 3, in which a solid foam cylinder (10) is mounted in the shaft (11) of a motor (12) in a casing (13) designed in such a way that contaminated air or other gas (indicated by solid arrows) is drawn along an inlet duct (14) and clean gas (indicated by an outline arrow) is ejected along the radius of the disc.

Claims

CLAIMS 1. An apparatus for removing solid particles from gases by means of a porous filter whose rotation provides the motive force for drawing the gas through itself.
2. An apparatus as claimed in Claim 1 in which the porous filter consists of a solid cylinder of plastic foam.
3. An apparatus as claimed in Claim 1 in which the porous filter consists of a hollow cylinder of plastic foam.
4. An apparatus as claimed in Claim 1 in which the porous filter consists of a solid spheroid of plastic foam.
5. An apparatus as claimed in Claim 1 in which the porous filter consists of a hollow spheroid of plastic foam.
6. An apparatus as claimed in any of the preceding claims in which the filter is mounted concentrically with a drill bit or burr and coupled to it so as to rotate with it.