# US 5,704,953 A · Forced air system air filter

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- Number: US 5,704,953 A
- Document ID: US5704953A
- Status: Granted
- Kind: A
- Application number: 08/624,135
- Filed: 1996-03-29
- Granted: 1998-01-06
- Earliest claimed: 1996-03-29
- Assignees: Air Kontrol, Inc.
- Inventors: Michael J. Stemmer
- Web page: https://patentgrep.com/patent/US5704953A

## CPC

- B01D 46/521: {using folded, pleated material}
- B01D 46/10: Particle separators, e.g. dust precipitators, using filter plates, sheets or pads having plane surfaces
- B01D 46/523: {with means for maintaining spacing between the pleats or folds}
- B01D 46/62: connected in series
- B01D 2267/40: Different types of filters
- Y10S 55/39: Electrets separator
- B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28)
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

## Abstract

An HVAC filter having a pleated paper filter and a plastic pre-filter, the filter and pre-filter are mounted in a parallel relation in the frame. The plastic pre-filter includes a plastic mesh having a plurality of openings, and an irregular surface on the inlet side to prevent matting of filtered material.

## Claims

### Claim 1

An air filter comprising:
a frame;
a pleated filter element supported by the frame; and
a substantially planar pre-filter formed from woven plastic strands and supported by the frame in a side-by-side relationship with the pleated filter to filter air which passes through the pleated filter.

### Claim 2 (depends on 1)

The filter of claim 1, wherein the pleated filter is formed from paper.

### Claim 3 (depends on 2)

The filter of claim 2, wherein the paper includes fiberglass fibers.

### Claim 4 (depends on 1)

The filter of claim 1, wherein the plastic strands have different diameters and are woven such that the pre-filter has an irregular surface.

### Claim 5 (depends on 4)

The filter of claim 4, wherein the plastic strands are polypropylene.

### Claim 6 (depends on 1)

The filter of claim 1, wherein the frame is rectangular, and is fabricated from elongated sections having a generally U-shaped cross-section.

### Claim 7 (depends on 1)

The filter of claim 1, wherein the frame is rectangular, and is fabricated from elongated sections having a generally U-shaped cross-section.

### Claim 8

An air filter comprising:
a frame;
a pleated filter element supported by the frame; and
a substantially planar woven, plastic mesh supported by the frame in a side-by-side relationship with the pleated filter to filter air which passes through the pleated filter.

### Claim 9 (depends on 8)

The filter of claim 8, wherein the pleated filter is formed from paper.

### Claim 10 (depends on 9)

The filter of claim 9, wherein the paper includes fiberglass fibers.

### Claim 11 (depends on 9)

The filter of claim 9, wherein plastic mesh includes plastic strands having different diameters and are woven such that the plastic mesh has an irregular surface.

### Claim 12 (depends on 11)

The filter of claim 11, wherein the plastic strands are polypropylene.

### Claim 13 (depends on 9)

The filter of claim 9, wherein the frame is rectangular, and is fabricated from elongated sections having a generally U-shaped cross-section.

### Claim 14

An air handling unit defining a path of airflow, the unit comprising:
a filter support; and
a filter assembly supported by the support within the path of airflow through the air handling unit, the filter assembly comprising;
a frame;
a pleated filter element supported by the frame, and.
a substantially planar plastic pre-filter formed from woven plastic strands and supported by the frame in a side-by-side relationship with the pleated filter to filter air which passes through the pleated filter.

### Claim 15 (depends on 14)

The filter of claim 14, wherein the pleated filter is formed from paper.

### Claim 16 (depends on 14)

The filter of claim 14, wherein the plastic strands have different diameters and are woven such that the pre-filter has an irregular surface.

### Claim 17

An air filter comprising:
a frame;
a pleated filter element supported by the frame; and
a plastic pre-filter formed from plastic strands supported by the frame in a side-by-side relationship with the pleated filter to filter air which passes through the pleated filter, wherein the plastic strands have different diameters such that the pre-filter has an irregular surface.

### Claim 18 (depends on 17)

The filter of claim 17 wherein the plastic strands are polypropylene.

### Claim 19 (depends on 17)

The filter of claim 17 wherein the plastic strands are woven.