This invention relates to a leak detection apparatus and method for detecting leaks from a high-pressure or low pressure vessel used to transport and/or store a substance.
Hazardous and flammable substances are often stored and transported in high-pressure vessels or other types of sealed vessels, such as railroad tankcars, semi-tractor trailer tanks, or other vehicles capable of hauling or holding a high-pressure vessel. Often these vessels can develop leaks around the valves and/or other access means used to fill, empty, and/or otherwise access the vessel, and/or pressure relief valves, due to neglect, environmental factors, or even normal use. Intermittent, temporary leaking can also occur during transport due to slamming of a manway lid of the vessel, rough road or rail conditions, and/or the impact of the vessel during humping of the railcars or hitching the semi-tractor trailer.
Leaking can be expensive to the shipments owner and dangerous to those working near the vessel. Current commercial leak monitoring systems are brought to the vessel to detect leaks and are used when the vessel is stationary, including during loading, unloading, and maintenance conditions. There is a need for a leak detection apparatus useful for detecting leaks of a vessel, such as a railroad tankcar, while in motion or while stationary. There is a need for a detection apparatus that can monitor shipments while the vessel is in motion or stationary and to transmit the detected information to a remote unit. There is a need for a system of detection apparatuses that can monitor information on a plurality of shipment vessels while stationary or in motion and transmit that information through wireless means to a central monitoring unit.
It is one object of this invention to provide a system of chemical sensors used to detect leaks of hazardous or flammable substances from vessels during transit, docking, and storage.
It is another object of this invention to provide a leak detection apparatus to protect the health and safety of workers and the environment.
It is another object of this invention to provide a system for monitoring safety, security, and inventory management of a shipment for shippers, operators, customers, or others involved in the mobile shipment of chemicals and hazardous materials.
It is another object of this invention to use at least one chemical sensor and/or other sensor type in combination with wireless technologies, such as a cell phone, a pager, wireless Internet, and/or other satellite technology, and/or Internet technology to transmit the status of a shipment, both while the shipment vessel is in motion and stationary, to a user designated site or a central site. The central site can distribute the status information via dedicated line or via a means such as the Internet, a pager, a cell phone, and/or other electrical or digital communication devices to persons having an interest in the shipment information.
The above objectives are accomplished, in one embodiment of this invention, by a leak detection apparatus having a first chemical sensor in communication with a first chamber of a shroud of a vessel and a second chemical sensor in communication with an ambient environment surrounding the shroud. Upon exposure to a predetermined substance, the first and second chemical sensors have a first and second chemical sensor output, respectively. A monitoring circuit can monitor the first chemical sensor output and the second chemical sensor output and detect a first increase of the first chemical sensor output and/or a second increase of the second chemical sensor output. The monitoring circuit signals an information unit in communication with the monitoring circuit. The signal can depend on the first increase and/or the second increase. The signal can also depend on no increase in the first and second chemical sensor outputs, thereby signaling favorable conditions. By comparing the first and second chemical outputs, the leak detection apparatus of this invention can be used effectively while the vessel is in motion. Also, the use of two sensor signals can reduce interference and false alarms because physical and chemical interferences like rapid temperature changes or high pollution levels can be determined by use of the second sensor.
In one embodiment, the shroud provides a barrier between the first and second chemical sensors resulting in detectable differences between the first and the second chemical sensor outputs. If a leak occurs in a chamber of the shroud the first chemical sensor output may have a greater increase and/or rate of increase than the second chemical sensor output. If a leak occurs in the ambient environment surrounding the shroud the second chemical sensor output will have a greater increase and/or rate of increase than the first chemical sensor output.
The information unit can be an alarm and/or other information reporting means that can inform of hazardous leaks or other information collected by the chemical and/or physical sensors and the monitoring circuit. The information unit can be a local information unit in proximity to the shroud and/or a remote information unit in communication with a transmitter and/or the monitoring circuit. The information unit can emit a signal showing the status of the sensors to various output devices. When the information unit is remote, the monitoring circuit emits an output signal to a transmitter which emits a status signal to a receiver in communication with the remote information unit. The remote information unit can receive signals from more than one transmitter, thereby monitoring more than one vessel. Shippers, operators, and customers can have access to the local and/or remote information units through various output devices, such as computers, cell phones, pagers, and personal digital assistants, to receive information such as the vessel location and vessel integrity associated with their shipments.
In another embodiment of this invention, one sensor is sufficient to detect the leak in the area near the vessel valves if the sensor can be adequately compensated for temperature changes, environmental effects, and interferences.
In another embodiment of this invention, at least one physical sensor is in communication with the monitoring circuit. The physical sensor can monitor temperature, pressure, movement and/or sounds around the vessel, and/or determine the position of the vessel by means such as satellite positioning technology. The physical sensor is in communication with the monitoring circuit and therefore can also be in communication with the remote information unit and provide information to interested parties.