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Filter

IP.com Disclosure Number: IPCOM000083761D
Original Publication Date: 1975-Jul-01
Included in the Prior Art Database: 2005-Mar-01
Document File: 2 page(s) / 25K

Publishing Venue

IBM

Related People

Gupta, O: AUTHOR [+2]

Abstract

This long-life filter doubles the effective surface area, without substantially increasing the thickness or amount of material used. Doubling the surface area of the filter extends the interval between cleanings, since the "dirt holding" capabilities have been doubled.

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Filter

This long-life filter doubles the effective surface area, without substantially increasing the thickness or amount of material used. Doubling the surface area of the filter extends the interval between cleanings, since the "dirt holding" capabilities have been doubled.

The surface area doubling is effected by forming the surface into a series of raised and sunken semiellipsoids. In the case of a hemispherical surface, the area is effectively doubled versus that of a flat-surface filter.

Referring to the figure, there is shown a side view showing the raised and sunken hemispherical surface configuration. Knowing that the area of a sphere is 4 pi r/2/, therefore the area of any of the hemispheres is 2 pi r/2/. The projected area, that is the area of flat filter material is pi r/2/.

Accordingly, the hemispherical surface area has effected a doubling of the surface area. It should be noted that the area increase is independent of the radius r. Of course, there is a limit on the radius r, because of manufacturing limitations on the one hand and taking into consideration that r has to be large compared to dust size.

A filter having the hemispherical surface area contour has been fabricated from foam with 25 ppi (pours per inch). The radius r is one-quarter inch and the thickness of the base t is one-quarter inch, thereby providing an overall thickness of three quarters of an inch.

The performance of this filter was compared to a standard, flat, foam filter, one-...