Gas separation – Two or more separators – Plies or layers of different characteristics or orientation
Reexamination Certificate
1999-10-04
2001-09-25
Simmons, David A. (Department: 1724)
Gas separation
Two or more separators
Plies or layers of different characteristics or orientation
C055S491000, C055S501000, C055S528000, C055SDIG003, C055SDIG007, C096S226000
Reexamination Certificate
active
06293983
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention is directed to filters for use in air filtration units.
2. Background Art
The present invention finds predominant use in the field of air filtration units. The term, air filtration unit, includes devices such as air extractor hoods typically found in commercial food premises, various air extraction devices and such like, and may extend to air conditioning units. The primary consideration is where there is an airflow to be filtered.
The air filtration elements which are traditionally used are generally constructed of a reusable material able to be cleaned or reconditioned. Traditional exhaust filter elements generally comprise metal mesh or honeycomb material supported by a frame. More recently, flame baffle filters have gained acceptance.
When filtering air in a food preparation environment, air laden with greasy cooking vapour, is drawn through the filters by fan assistance. The greasy droplets are trapped by the filters and the “purified” air passes through ducting to be released into the environment outside the building. In the process, the interior of the hood, fan and ducting become progressively and often quickly contaminated and greasy.
The build up of contaminants in the ducting constitutes a significant fire hazard.
The filter elements often become quickly soiled depending upon conditions of use and require regular cleaning to maintain an efficient filtering action to provide, e.g. clean air in the workplace. If left for a prolonged period, severe clogging of the filter element may occur, reducing airflow, filtering performance and creating unpleasant working conditions.
Badly soiled filters can also release trapped contaminants onto food and food processing surfaces beneath the air filter.
Cleaning filter elements is messy, often inconvenient and deposits may be difficult to remove, requiring quite harsh chemicals. Cleaning the hood interior, fan and ducting is even more difficult because of restricted access.
In larger population centres, specialist service companies are often employed to remove soiled elements by roster and to then fit clean replacements, (sometimes unnecessarily), otherwise staff or proprietors must attempt the work themselves.
The continuing rapid growth of the fast food industry in which deep fat frying methods are often employed, ensures that the extent of the problems associated with exhaust hoods, metal filters and contaminated flues are similarly multiplying.
There are therefore, difficulties involved with the use of filter elements commonly in use, arising from the neglect of their cleaning. This neglect is usually an indirect consequence of the difficulties associated with cleaning or can simply arise from a desire to keep costs down.
SUMMARY OF THE INVENTION
It is an object of the present invention to address the foregoing problems or at least to provide the public with a useful choice.
Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only.
According to one broad aspect of the invention there is provided a filter assembly for use in an air filtration unit comprising a filter disposed across an airflow aperture and a pre-filter disposed such that airflow passes therethrough prior to passing through said filter.
Preferably the pre-filter is of a disposable type.
According to a preferred form the pre-filter is made from natural or synthetic fibres. The pre-filter can be of woven, non-woven or needle punched construction. In a preferred embodiment the pre-filter is constructed solely or primarily of wool. The pre-filter can include reinforcement means.
In one form of the invention the pre-filter is removably fastened to the filter. In another form the pre-filter is located in position by the filter fitting across said airflow aperture.
A second broad aspect of the invention provides a filter element characterised in that the filter element is formed principally from wool. The wool can be in woven, non-woven or needle punched form and optionally can include reinforcement means.
According to a third broad aspect of the invention there is provided a method of modifying an air filtration unit having a filter element disposed in an airflow passage or across an aperture into an airflow passage, the method being characterised by the mounting of a pre-filter disposed adjacent or prior to the filter element.
In a preferred form the pre-filter is formed principally of natural or synthetic fibres which can be in woven, non-woven form or needle punched. The pre-filter can be formed from wool. The pre-filter can be of a disposable type.
According to one form of the method the pre-filter is mounted with the filter element.
REFERENCES:
patent: 3660969 (1972-05-01), Fox
patent: 4336038 (1982-06-01), Schultheiss et al.
patent: 4340402 (1982-07-01), Catron
patent: 4689058 (1987-08-01), Vogt et al.
patent: 4921512 (1990-05-01), Maryyanek et al.
patent: 5154161 (1992-10-01), Rogers et al.
patent: 5318607 (1994-06-01), Malloy et al.
patent: 5419953 (1995-05-01), Chapman
patent: 5529838 (1996-06-01), Lee
patent: 5874052 (1999-02-01), Holland
patent: 5935303 (1999-08-01), Kimura
patent: 1200888 (1970-08-01), None
patent: 2 069 368 (1981-08-01), None
patent: 2 287 664 (1995-09-01), None
patent: 61-71814 (1986-04-01), None
patent: 8173843 (1996-07-01), None
patent: WO 95/05234 (1995-02-01), None
Hopkins Robert A.
Simmons David A.
Young & Thompson
LandOfFree
Filter assembly having a disposable pre-filter does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Filter assembly having a disposable pre-filter, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Filter assembly having a disposable pre-filter will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2458213