Fluid handling – With indicator – register – recorder – alarm or inspection means – Position or extent of motion indicator
Reexamination Certificate
2000-05-03
2001-05-29
Lee, Kevin (Department: 3753)
Fluid handling
With indicator, register, recorder, alarm or inspection means
Position or extent of motion indicator
C137S556000, C251S248000
Reexamination Certificate
active
06237626
ABSTRACT:
BACKGROUND OF THE INVENTION
1.Field of the Invention
This invention relates generally to tank cargo valves, and more particularly to valves in the bottom of deep tanks and operated by a long shaft with an operating handle at or above the top of the tank.
2. Description of the Prior Art
Many barges have liquid cargo holding tanks with valves located at or near the bottom, inside the tank. The tanks are in abutting or closely-spaced relationship. Therefore, the valves are inside the tanks near the bottom and must be operated from the deck above the valve. For this purpose, a long shaft is used to operate the valve, one end of the shaft being at the valve, and the upper end having a hand wheel on it above the deck of the barge for operation by a person on the deck. One type of valve is a gate valve in which a gate is raised or lowered, respectively, to open or shut the valve. For some such valves, the operating shaft rises to open the gate and descends to close the gate. In those cases, it is relatively easy to determine from the deck level, whether the gate is open or shut. The other type of gate valve is a non-rising stem valve. In these, the operating shaft is screwed into the gate or an attachment to the gate, rather than to the valve body. Consequently, the valve can be opened and shut without the operating shaft rising or descending. Therefore, there is no way to determine from deck level, whether the valve is open, other than turning it clockwise until it stops, indicating that the valve is shut, or turning it counterclockwise until the operating handle stops, typically indicating that the valve is open. But sometimes valves get stuck. In such cases, the operating handle will not turn either clockwise or counterclockwise. Therefore, the operator does not know whether the valve is open or shut.
To address this problem, a valve position indicator has been used in the past so that, while the valve is being opened or closed, the indicator, at or above deck level, will track the valve gate position as it is being opened or closed, so that the operator can determine at a glance, whether the valve is opened or closed.
Many barges with non-rising operating shafts, do not have any valve position indicator on them. But as such barges age, there is a greater likelihood that the valve may become stuck open or closed. If the operator is not able to turn the shaft either way, sometimes assistance will be used in the nature of a long bar or a pipe wrench with a bar on it and placed on the shaft or through the handle to add leverage. The result of such efforts frequently is damage or destruction of the valve, or inability to move the valve one way or the other.
To avoid such problems governmental authorities require that all barges having non-rising stem valves, have valve position indicators incorporated with them. Prior art efforts have provided a valve position indicator near the top of the shaft. But the only one of which I am aware, requires removal of the hand wheel from the top of the shaft in order to install a portion of the indicator assembly. But a problem frequently encountered with such an effort is that the hand wheel cannot be removed because it is either welded onto the shaft or has so badly corroded that it will not come off. In such cases it is necessary to use a cutting torch to remove the hand wheel. But a cutting torch cannot be used until the barge is “gas free”. Thus it is necessary to take the barge out of service and send it to a facility which has the ability to clean and free the barge of any combustible gases. The cost of this service alone is in excess of $5000. In addition, of course, there is the factor of loss of use of the barge. The present invention is addressed to solving this problem.
SUMMARY OF THE INVENTION
Described briefly, according to one embodiment of the present invention, a valve position indicator assembly is mounted at the valve operating shaft and fixed in position relative to the tank above the top of the tank. It includes a two-piece gear that is clamped onto the valve operating shaft. A mating gear is mounted on a shaft parallel to the valve operating shaft and having a screw thread on it. A nut mounted on the screw thread has an indicator stem or pointer mounted to it and which moves vertically relative to the screw as the shaft is rotated and advances between a lowermost position on an indicator scale indicating that the valve is closed, and an uppermost position on an indicator scale indicating that the valve is open, as the valve operating shaft is rotated to operate the valve between the closed position and the open position.
REFERENCES:
patent: 3927702 (1975-12-01), Ingle et al.
patent: 4384704 (1983-05-01), Wolff
patent: 5076308 (1991-12-01), Cohen
patent: 5538037 (1996-07-01), Pizao
patent: 6009899 (2000-01-01), Polutnik
Electromechanical Research Laboratories Inc.
Lee Kevin
Woodard Emhardt Naughton Moriarty & McNett
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