Receptacles – Closures – With closure opening arrangements for means
Reexamination Certificate
1999-07-27
2001-01-16
Newhouse, Nathan J. (Department: 3727)
Receptacles
Closures
With closure opening arrangements for means
C220S345200, C220S345400, C220S345600
Reexamination Certificate
active
06173854
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a port closure for storage and transport tanks and, in particular a port closure that can withstand a pressure differential.
BACKGROUND OF THE INVENTION
Every storage tank and transport tank has an access port. The access port may be large enough for a person to enter for the purpose of inspecting the interior of the tank or the access port may be only large enough to permit the passage of matter into the tank. With some commodities it is important that the tanks have port closures that can withstand a pressure differential between internal and external pressure. For example, in tanks used for the storage or transportation of granular or powder form dry bulk goods (such as flour, salt, cement, lime, and cereal grains) the contents are pneumatically transferred. Pneumatic transfer systems do not work properly unless the closure on the access port can maintain a pressure differential between interior pressure and exterior pressure.
The port closures in common use for such applications at the present time consist of an external lid. This external lid is held in position by a series of camlocks spaced evenly about a circumference of the access port. These closures have a number of problems. A first problem is that they are prone to leakage. A second problem is that the camlocks must be manually released. This requires a person to climb up onto the tank, and creates a potential safety hazard. The severity of the hazard depends upon the height of the tank, lighting conditions, weather conditions (wind, rain, etc), and other surrounding circumstances. A third problem is that care must be taken to ensure that the pressure within the interior of the tank is released prior to attempting to open the closure. If a pressure differential exists, the closure will open under pressure with a violent force. This violent opening force has resulted in a number of injuries and deaths as the person opening the closure has been struck by the closure and, in some cases, knocked off of the tank.
SUMMARY OF THE INVENTION
What is required is an alternative form of port closure for a tank.
According to the present invention there is provided a port closure for a tank. The port closure involves a combination which includes a tank, a closure member and an actuator. The tank has defining walls, an exterior surface, an interior surface, an interior cavity and an access port. The closure member is disposed within the interior cavity of the tank. The closure member has an access port engaging face that is larger than a cross-sectional area of the access port. The actuator is coupled with the closure member and moves the closure member between a first position in which the access port engaging face closes the access port and a second position laterally spaced from the access port.
The port closure, as described above, provides a number of advantages over an externally applied cam-lock lid. As the port closure is installed within the interior cavity of the tank, internal pressure within the tank tends to press the closure member against the access port; thereby reducing the possibility of leakage. The port closure is moved between the first position closing the access port and the second position by the actuator. There is no need for the closure member to be manually opened. This virtually eliminates the safety hazards formerly associated with opening and closing the access port.
There are various forms of actuators that can be used for the remote actuation of the closure member. The preferred form is a telescopically extendible member. For example, the telescopically extendible member can consist of a cylinder connected by fluid lines to a fluid control system that controls the supply of fluid to the cylinder to telescopically expand and contract said cylinder. This enables the closure member to be moved between the first position and the second position either hydraulically or pneumatically. With a transport tank, the hydraulic or pneumatic lines can be run off of the hydraulic or pneumatic systems of the transport vehicle.
Although beneficial results may be obtained through the use of a port closure, as described above, such a port closure can only be installed in a tank during fabrication. It is impossible to retrofit an existing tank with such a port closure installed within the interior cavity of the tank without taking the tank apart. According to another aspect of the present invention there is provided a method of retrofitting a tank with a port closure. A first step involves providing a tank having defining walls, an interior cavity and an access port through the defining walls to the interior cavity. A second step involves providing a closure member having an access port engaging face larger than a cross-sectional area of the access port. A third step involves cutting a temporary slotted opening through the defining walls of the tank large enough to accommodate the closure member. A fourth step involves passing the closure member through the slotted opening into the interior cavity. A fifth step involves coupling the closure member with an actuator positioned within the interior cavity that moves the closure member between a first position in which the access port engaging face closes the access port and a second position laterally spaced from the access port. A sixth step involves closing the temporary slotted opening.
Although beneficial results may be obtained through the use of a port closure, as described above, there are measures that can be taken to improve the sealing engagement between the closure plate and the access port. Even more beneficial results may, therefore, be obtained when a seal is mounted to either the defining walls on the interior surface of the tank circumjacent the access port or the access port engaging face of the closure member.
REFERENCES:
patent: 672641 (1901-04-01), Hirt
patent: 1124395 (1915-01-01), Cottrell
patent: 2224094 (1940-12-01), Small
patent: 2842283 (1958-07-01), Smith
patent: 3131925 (1964-05-01), Coats
patent: 3142410 (1964-07-01), Arnold
patent: 3339785 (1967-09-01), Nugent
patent: 4709901 (1987-12-01), Pierson et al.
patent: 5190182 (1993-03-01), Copas et al.
patent: 5507408 (1996-04-01), Mosior et al.
Labelle Robert Jacques
Lyseng Richard Donald
Christensen O'Connor Johnson & Kindness PLLC
Newhouse Nathan J.
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