Ships – Building – Freighters
Reexamination Certificate
1997-10-01
2001-04-17
Avila, Stephen (Department: 3617)
Ships
Building
Freighters
C114S07400A
Reexamination Certificate
active
06216623
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to containers for liquids, and more particularly to methods and apparatus for detection of liquid levels of liquids that have either leaked into space between the outer hull and inner hull of a double-hulled ship or barge or the like or are purposefully pumped into a tank.
2. Description of the Prior Art
Modern tanker ships and barges are being designed and built with space between the outer hull and an inner hull in an effort to avoid puncture of cargo tanks, and thereby avoid leakage of liquid contents from cargo tanks into a waterway as a result of collision damage. Instead of there being a single void space around the entire inner hull, there are partitions so as to divide the space into a plurality of compartments so that, in the event of a puncture of the outer hull, only a compartment space can be flooded while the remaining compartments remain dry. Also, in the event of a leak developing at some point in the wall of the inner hull, such leakage will only enter the compartment between hulls and not leak out into the waterway if the outer hull is not damaged at the site of that compartment.
In order to be sure that there is no leakage into a compartment from either the waterway or a cargo tank inside the vessel, it is desirable to be able to detect the presence of liquid in a compartment. Heretofore, that has not been easy. First of all, the compartments are usually sealed so as to avoid entry of water or other liquid from the top, as from a deck, for example. Therefore, if presence of liquid in such compartment is to be detected, it has been necessary to provide a hole in the deck and insert a pole through the hole to the bottom of the compartment, and then raise the pole to see if there is any liquid on the lower end of the pole. Considering the fact that such compartments may be as deep as twelve feet on a river barge, and much deeper on an ocean tanker, the handling of such a measuring pole is not easy. Also, it is time consuming.
It is an object of the present invention to facilitate determination of the presence and depth of liquid in a normally void space in a shipping vessel.
Furthermore, when filling tanks with expensive or dangerous compounds it is desirable to prevent overflow of the liquid.
Thus it is a further object of the present invention to protect against overfills in tanks by determining when a liquid has reached a predetermined critical level.
SUMMARY OF THE INVENTION
Described briefly, according to a typical embodiment of the present invention as implemented in a double-hulled, river-going barge, each of the void space compartments is provided with a permanently installed tube extending from the deck down to a point near the bottom of the compartment. The tube is adapted at its top for normally receiving a quick-connect sealing closure. The tube has an opening at or near the bottom end of it. Therefore, any liquid collecting in the compartment can rise inside the tube, particularly if a vent opening in the tube wall near the top of the compartment permits any air in the tube to escape as liquid rises in it.
A measuring instrument is provided with a quick-connect coupling readily receivable and mating with the coupling at the top of each tube after the tube closure has been removed. The measuring instrument includes a transceiver including a transducer selectively operable to transmit ultrasonic energy pulses down the tube, and receive reflected ultrasonic energy pulses. The elapsed time is measured and compared to a master, to calculate the depth of liquid, if any, in the compartment. The calculated depth is displayed on an indicator and, if more than a predetermined acceptable limit, will also illuminate a light or energize a sounder to indicate an alarm condition. The master time/depth information is obtained from a tube which is like those in the compartments except that it has a closed bottom end at a known distance from the transducer when mounted to it, to establish a reference dimension.
Each tube has a bar code identification including two components, one of them being a barge identification and the other being the compartment identification on the barge. The measuring instrument has a bar code reader on it to identify the particular barge and compartment along with the depth indication reading. Information regarding the readings at the various compartments on a barge can be stored in the measuring instrument and subsequently downloaded to a separate computer.
According to one method of use of the apparatus, an individual can walk the barge from end-to-end up one side and down the other. In a preferred mode, the operator will stop at the master tube first and obtain information relating to the master tube length to automatically establish a time factor for the passage of sound in atmosphere at the typical temperature of the compartments in the barge and thereby obtain a reference time useful in subsequent locations on the barge to directly compute and indicate the depth of liquid, if any, in a compartment. In this context, the term “sound” is used, but should not be construed to be limited to an energy wave frequency range that can be heard by humans.
Following calibration of the instrument at the master tube, the operator then moves from that tube to the first compartment measurement tube, connects the instrument, activates the instrument and notes the result. This is done in sequence from one compartment to the next. If, at any compartment, the instrument detects a liquid depth greater than a predetermined acceptable maximum, the alarm condition will be announced not only through the display, but also with some other annunciator such as light, bell, buzzer, or combination thereof. Then the operator knows that a pump is needed to pump that compartment. Once that has been done, check of the other remaining compartments can be performed.
As an alternative approach, the operator can move from compartment-to-compartment on one barge and then on another barge in a string of barges and, either simultaneously through a radio link, or subsequently through a direct wire download, can transmit that information including bar code identification and the depth measurement for each compartment to a computer which then applies the correct sound-velocity-in-air correction factor (UE) to the signals received for each compartment and computes the depth of liquid, if any, in each compartment and, on a printout, flags each compartment for which there is an alarm condition present, the proper UE factor for each barge being predetermined by the master tube measurement for that barge, wherever it occurs in the sequence of tubes checked. There is also provision for ascertaining or assuring that all measurements are made within a reasonable time from the time of measurement of the master tube so that all measurements are representative of essentially the same compartment temperature conditions for a given barge.
In a related application, the invention can be used to provide overfill protection for cargo holds in tankers, or other fluid containers such as railroad tank cars, for example. In such an application, the relative location of the critical fluid level of interest would presumably be nearer the top of the container, but the measuring device could be very similar to the one for the void space leakage detection application. After detecting that the fluid level had exceeded a predetermined level, the pump can be stopped, thereby preventing overfilling of the tank.
REFERENCES:
patent: 4063457 (1977-12-01), Zewkulin et al.
patent: 4815323 (1989-03-01), Ellinger et al.
patent: 4984449 (1991-01-01), Caldwell et al.
patent: 5054319 (1991-10-01), Fling
patent: 5076101 (1991-12-01), Lazure
patent: 5095748 (1992-03-01), Gregory et al.
patent: 5127266 (1992-07-01), Maresca et al.
patent: 5131271 (1992-07-01), Haynes et al.
patent: 5271350 (1993-12-01), Newburger
patent: 5319973 (1994-06-01), Crayton et al.
patent: 1749717 A1 (1992-07-01), None
Avila Stephen
Electromechanical Research Laboratories Inc.
Woodard Emhardt Naughton Moriarty & McNett
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