High efficiency permanent air filter and method of manufacture

Details High efficiency permanent air filter and method of manufacture High efficiency permanent air filter and method of manufacture

1998-09-18

2000-05-02

Chiesa, Richard L.

Gas separation: apparatus

Electric field separation apparatus

Including gas flow distribution means

55486, 55521, 55DIG5, 95 57, 96 69, 264258, 264DIG48, B01D 2706

Patent

active

060568097

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL BACKGROUND

The present invention relates to filters cleanable by washing or vacuuming or the like for inlet air heating and air conditioning systems used in residential or commercial buildings and, more particularly, this invention relates to an electrostatic filter for such systems having an extended service life.


BACKGROUND ART

Inlet air filters for heating and air conditioning systems have been in use for decades. The inlet air or primary filter was originally intended to protect the heating coils and mechanical devices such as fans from damage by airborne particles. As the harmful effect of inhaled particles on human health became known, inlet air filters were designed remove this particulate matter from the air.
The most popular prior art configuration is a thin, rectangular, disposable filter. The filter contains fiberglass, animal hair, fibrous foam or polymeric media or aluminum mesh encased in a cardboard or plastic frame. Prior art filters can comprised polyester panels, urethane foam or latex coated animal hair. Recently, prior art filters containing static or passive electrostatic media have become available.
Most residential resistance specifications require air filters to have an initial pressure drop of no more than 0.22 inches of water for an air flow rate of 300 feet per minute. The dust spot efficiency for typical prior art air filters tested using ASHRAE 52.1-1992 is 20% or less. The ASHRAE efficiencies of four types of commercially available filters follows:


TABLE 1 ______________________________________ Area of Media Filter Type Square Feet ASHRAE EFFICIENCY ______________________________________ Fiberglass Throwaway 4.0 <20% Electrostatic (Passive) 4.0 20% Electrostatic (Fibers) Up to 8.9 30% Pleated Polyester Blend Up to 6.9 25% ______________________________________
When these filters are first placed in use across an air stream, they have a very low filtering efficiency. Typically, the exhaust or dust spot efficiency is about 8%. However, as dust particles are collected, the dust collection efficiency can increase to approximately 20%. At this point, the filter is ready to be replaced. Prior art filters are usually difficult to clean since the dust particles become embedded in the media.
Another current concern is the recognition that particles below 10 microns are not filtered by the cilia hairs in the nose and are therefore inhaled into a human lung. Fibrous particles such as asbestos and fiberglass are known to cause respiratory diseases. Most current inlet air filters for heating and air conditioning systems are not very efficient in capturing these small particles. Filters containing layers of electrostatic media perform better within this range of particles but these filters also become clogged. Since they cannot be efficiently cleaned they must be replaced.


DISCLOSURE OF THE INVENTION

It has been discovered in accordance with the invention that the angle of approach of the air stream effects the particle capture efficiency, the life of the filter between cleaning and the difficulty of cleaning the filter. The filter of the invention causes a non-perpendicular path of air flow resulting from the corrugated or pleated configuration of the novel air filter. Because of the corrugated configuration, more surface area exists than with a standard, flat, prior art air filter. The increased surface area of the novel filter also results in a lower pressure drop than experienced with prior art electrostatic air filters. The filter has significantly longer life between cleanings and it is very easy to clean. The novel air filter's efficiency for removing particulate matter is also an improvement over the prior art.
The purpose of the invention is to provide an upstream passive electrostatic layer disposed upon a filter media layer wherein both layers are in a corrugated or pleated configuration to increase filter surface area when compared to a flat surfaced air filter.
A number of embodiment configurations can be utilized

REFERENCES:
patent: 4375718 (1983-03-01), Wadsworth et al.
patent: 4886526 (1989-12-01), Joannou
patent: 4978372 (1990-12-01), Pick
patent: 5240479 (1993-08-01), Bachinski
patent: 5403383 (1995-04-01), Jaisinghani
patent: 5419953 (1995-05-01), Chapman
patent: 5496507 (1996-03-01), Angadjivand et al.
patent: 5540761 (1996-07-01), Yamamoto
patent: 5645057 (1997-07-01), Watt et al.
patent: 5651811 (1997-07-01), Frey et al.
patent: 5667562 (1997-09-01), Midkiff
patent: 5690719 (1997-11-01), Hodge
patent: 5792242 (1998-08-01), Haskett
patent: 5922096 (1999-07-01), Stemmer
patent: 5989303 (1999-11-01), Hodge

Affiliated with

Also associated with

Rating

High efficiency permanent air filter and method of manufacture does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with High efficiency permanent air filter and method of manufacture, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and High efficiency permanent air filter and method of manufacture will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-1591138