Fluid handling – Diverse fluid containing pressure systems – Liquid filling by evacuating container
Reexamination Certificate
1999-09-16
2001-10-23
Michalsky, Gerald A. (Department: 3753)
Fluid handling
Diverse fluid containing pressure systems
Liquid filling by evacuating container
C137S236100
Reexamination Certificate
active
06305403
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to fluid drains, and more particularly to vacuum drainage systems.
BACKGROUND OF THE INVENTION
Various types of drainage systems are used to transport waste fluid from a source to a desired collection point. Gravity drainage systems, for example, use the pull of gravity to transport waste fluid. Such systems have many drawbacks. For example, options for the layout of gravity drainage piping are limited since the piping must be located below the waste fluid source and must continuously slope toward the collection point. The waste fluid source is often located on a concrete pad, so piping must be laid out before the concrete is poured. In addition, it is overly difficult to renovate or add plumbing to a gravity drainage system due to the piping location requirements, and personnel are often displaced during renovation, resulting in loss of production time.
Vacuum drainage systems provide an alternative to conventional gravity drainage piping. Such systems typically comprise a vacuum source connected to a collection tank. A main drainage pipe is attached to the collection tank, and one or more collection branches fluidly communicate with the main drainage pipe. Each collection branch typically includes a vertical riser section having an interface valve disposed therein. A buffer for collecting waste fluid from a source is attached to a bottom end of the riser.
In operation, waste fluid initially collects in the buffer. When a fluid level is sensed in the buffer, the interface valve is opened to transfer vacuum to the buffer. The vacuum acts on a downstream side of the buffer, while an upstream side is open to atmosphere. As a result, the vacuum creates a pressure differential across the fluid in the buffer which pushes the fluid up the riser to the main drainage pipe in the form of a discrete volume or slug of waste fluid. During normal operation, the interface valve remains open for an additional period of time to pull a volume of air into the system behind the slug to ensure that the fluid is transported to the main drainage pipe. Depending on the capacity of the vacuum source, the vacuum created in the riser is capable of transporting fluid up vertical lifts, thereby allowing for greater flexibility in locating piping. As a result, vacuum drainage systems simplify installation and renovation of plumbing fixtures.
In many applications, the plumbing fixture always supplies a low volume flow of waste fluid to the buffer, so that the vacuum drainage system operates as described above. Certain plumbing fixtures, however, are capable of delivering a high flow of waste fluid which may cause the system to stall. For example, a vacuum drainage system used to collect waste fluid from a refrigerated case normally receives a low volume flow of condensate from the case. The case, however, is periodically washed, creating a high flow situation. If a wash down occurs when the system has a low vacuum level, a portion of each slug will not reach the top of the riser and will flow back into the buffer. Over time, the riser will become filled with a solid column of fluid. The vacuum source attached to the main vacuum pipe is often sized for a particular riser lift and slug size and, therefore, is often not capable of lifting the solid fluid column through the riser. As a result, the system stalls, unable to accept additional waste fluid, and waste fluid may back up through the buffer and flood the surrounding area. The only previously known solution for preventing such stalling is to select a vacuum source having a greater capacity, which is overly costly and unnecessary during normal operation. Moreover, lifting the solid fluid column up certain lifts is beyond capabilities of any type of vacuum source, and therefore the stalling problem is unresolved.
SUMMARY OF THE INVENTION
In accordance with certain aspects of the present invention, a vacuum drainage system is provided for collecting waste fluid from a source. The vacuum drainage system comprises a buffer positioned to receive waste fluid from the source, the buffer having an inlet opening and an air intake opening. A vertical riser has a lower riser section in fluid communication with the buffer and an upper riser section. A normally closed interface valve is disposed between the upper and lower riser sections and is operable to open in response to a fluid level in the buffer. A main drainage pipe is in fluid communication with the upper riser section and is maintained under vacuum. A aeration point is formed in the lower section of the riser at a height above a low point of the riser. The aeration point establishes fluid communication between an interior of the riser and atmosphere so that, when the interface valve is open, air at atmospheric pressure is pulled through the aeration point and into the lower riser section.
In accordance with additional aspects of the present invention, a vacuum drainage system is provided for collecting waste fluid from a source and comprises a main drainage pipe maintained under vacuum. A collection branch is in fluid communication with the main drainage pipe and includes a vertical riser section. An interface valve is disposed in the collection branch and divides the collection branch into an upstream riser section in fluid communication with the main drainage pipe and a downstream riser section. The interface valve is operable between a closed position, which isolates the upstream riser section from the downstream riser section, and an open position, which establishes fluid communication between the upstream and downstream sections. A buffer is in fluid communication with the upstream section of the collection branch and is positioned to receive fluid from the source, wherein the interface valve actuates to the open position in response to a fluid level in the buffer. An aeration pipe is attached to the upstream riser section at a height above a low point of the upstream riser section and establishes fluid communication between an interior of the upstream riser section and atmosphere so that, when the interface valve is in the open position, air at atmospheric pressure is pulled through the aeration point and into the upstream riser section.
In accordance with still further aspects of the present invention, aeration apparatus is provided for attachment to a riser incorporated into a vacuum drainage system. The aeration apparatus comprises a housing defining an inner chamber and having an open end adapted to fluidly communicate with an interior of the riser. A plurality of apertures extend through the housing to establish fluid communication between the inner chamber and an exterior of the housing. A blocking member is moveable along the housing to block one or more of the apertures from fluidly communicating with the open end of the housing.
Other features and advantages are inherent in the apparatus claimed and disclosed or will become apparent to those skilled in the art from the following detailed description and its accompanying drawings.
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Stradinger Jay D.
von Palffy Bjorn
Wallace Douglas M.
Evac International Oy
Marshall Gerstein & Borun
Michalsky Gerald A.
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