Cleaning and liquid contact with solids – Processes – Hollow work – internal surface treatment
Reexamination Certificate
2001-10-29
2003-12-02
Gulakowski, Randy (Department: 1746)
Cleaning and liquid contact with solids
Processes
Hollow work, internal surface treatment
C134S024000, C239S288300
Reexamination Certificate
active
06655393
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to the cleaning of ventilation passages such as ducts or flues. More specifically, the present invention relates to the cleaning and maintenance of ventilation passages associated with kitchen ventilation systems wherein grease or other airborne particulates may accumulate within the passageway structure.
2. State of the Art
Restaurants, cafeterias or other such facilities where large amounts of food are cooked and prepared typically implement cooking hoods adjacent the food preparation area. Cooking hoods are large ventilation openings, often overhanging the cooking area such as the stove. The hoods are coupled with air passages, such as ducts or flues, which lead to an external environment. An air handling unit is coupled to the air passages to draw air from the cooking area through the passages and to the external environment. In essence, the hood is an exhaust system to draw smoke, heat and gases created in the cooking and preparation of food away from the cooking area. Such systems are not only desirable, but are typically required for facilities preparing large quantities of food. These systems, however, are not limited to commercial establishments and are often found in residential dwellings.
Over an extended period time, use of the hood and exhaust system results in an accumulation of cooking grease and other associated particulates along the interior of the ventilation ducts. Accumulation of grease within the exhaust system poses various hazards and further impacts the safety and efficiency of the system. The most obvious hazard is the possibility of a fire. The close proximity of the exhaust system to the cooking area, typically above the stove or cooking range, combined with the hot gases passing through the ventilation ducts, creates a serious threat of combustion within the ducts which may develop if the system is not properly maintained. Accumulation of grease within the ductwork, for any length of time, also negatively affects the cleanliness and sanitary condition of a food preparation area, which can affect both food preparers and patrons.
Beyond sanitary and safety concerns, the operation of an exhaust system can be impeded without proper cleaning and maintenance of the duct system. Air handling systems are designed to operate at specific airflow capacities. Typically, a given facility is designed to have an air supply and an air return or, alternatively, an exhaust. It is noted that an air return and an air exhaust are not the same concept. Air return typically refers to the passage of a volume of air from a specific location within a building to the air handling unit for conditioning of the air and subsequent reintroduction of the air into the building. On the contrary, the term exhaust more typically refers to the removal of air from an interior of a building to an external environment. The integration of the supply, return, and exhaust subsystems into a complete system requires design and adjustment of each subsystem with regard to the rate of airflow (expressed in cubic feet per minute, or CFM) imposed upon a particular environment. The system may be designed to create a positive pressure requiring a net positive supply of air (i.e., the supply being rated at a higher CFM than the return/exhaust). Conversely, a system may be designed to create a negative pressure requiring a net negative supply of air. The most common design is a balanced system wherein the supply of air equals the return and/or exhaust of the air.
The intended use of a specific room, such as for cooking, determines, at least in part, the design of the air system. With this in mind, the accumulation of grease or other materials within a ventilation duct can restrict airflow and prevent the overall air system from operating efficiently. For example, an eight inch diameter duct experiencing a quarter inch accumulation of grease on the interior walls represents approximately a thirteen percent reduction in area. A reduction in the cross sectional area of the duct results in an altered rate of air flow thus disrupting the overall system performance.
To ameliorate the above hazards and impediments, ducts must receive regular cleaning and maintenance. Indeed, with regard to commercial establishments, local ordinances often impose scheduled cleaning of such systems. However, such scheduled cleaning is not always performed. Noncompliance may be based upon a number of factors. Removal of accumulated grease from a ventilation system is typically a difficult and time consuming process. The tight confined spaces of a ventilation system make it extremely difficult to manually remove accumulated grease. For example, a ventilation duct running from the cooking area to an external outlet is typically formed of numerous vertical, horizontal and angular sections joined together. The angular connection of each section makes it difficult for cleaning implements to pass from one section to another. Thus, manual cleaning is typically required, which entails cleaning the ducts section by section. Furthermore, each section varies in length. In many cases a length of duct may be a hundred feet or more requiring clean-outs, or access doors, to be spaced along the length. Each clean-out must then be accessed individually in order to appropriately clean the entire length of duct. The job is even more onerous when the length is horizontally positioned, and the cleaning process cannot be assisted by gravity to help extricate the grease from the duct. Manual cleaning of such exhaust systems is tedious, time consuming, and not always effective.
To assist in the cleaning of ventilation ducts, various systems and devices have been implemented. However, these devices have not been entirely effective and, in many instances, have created additional difficulties. For example, U.S. Pat. No. 3,795,181 issued to Lawson discloses an apparatus for cleaning a ventilation flue utilizing a fixture mounted within the interior of the flue or duct. The system includes a plurality of nozzles or spraying devices mounted on a common tube. A turbine is mounted at the base of the tube causing the tube to rotate about its longitudinal axis upon the passage of fluid through the turbine. While this system may be effective in cleaning the surface of the duct adjacent the plurality of nozzles, it poses various problems. A system of this type does not account for the need to clean out multiple sections, whether they be vertical, horizontal or angular. Indeed, the disclosure only teaches the cleaning of the first vertical section immediately adjacent the hood, or ventilation inlet. Additionally, the system must be physically mounted within the ventilation ductwork requiring various physical modifications to the ductwork and hood. Such a device may be difficult to implement in an existing ventilation system. As a permanent fixture within the duct or flue, the device presents an additional surface to which grease and other particulates can adhere leading to an accumulation of grease within a smaller region of the duct.
Another approach may be seen in U.S. Pat. No. 4,031,910 issued to Lawson. The device disclosed attempts to address the issue of cleaning independent duct lengths regardless of angular orientation. The device also utilizes a tube containing a plurality of spray nozzles, the tube rotating about its longitudinal axis. However, the instant device attempts to put an individual rotating tube in each section of duct, with pipe fittings such as elbows connecting each rotating tube section. While this device attempts to address the issue of cleaning each duct section regardless of its angular orientation, it still poses a few drawbacks. Again, this device is a permanent fixture to be mounted within the ducts. Installation of such a device undoubtedly requires disassembly of any existing ductwork. Such an installation would be time consuming and would likely be cost prohibitive. Thus, there is little likelihood that owners of existing systems would im
Chaudhry Saeed T
Grease Duct Technologies, LLC
Gulakowski Randy
TraskBritt
LandOfFree
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