Fluid handling – Destructible or deformable element controlled – Destructible element
Reexamination Certificate
1999-02-25
2001-04-17
Rivell, John (Department: 3753)
Fluid handling
Destructible or deformable element controlled
Destructible element
C137S487500, C137S596170, C251S129040, C251S294000
Reexamination Certificate
active
06216719
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is directed to a safety system for transfer of pressurized fluids. In particular, the present invention is directed to an automatic shutoff system for transfer of pressurized fluids from a cargo tank vehicle to a storage container through a delivery hose.
2. Prior Art
Pressurized fluids, such as compressed liquid gases, are utilized in a variety of applications. Liquified compressed gases include carbon dioxide (CO
2
), butane (C
4
H
10
), anhydrous ammonia (NH
3
), and propane(C
3
H
8
). Propane and butane (known commercially as LP gas or LPG) have an extremely wide range of domestic, industrial, and agricultural uses. Among the uses are appliance fuel, industrial and utility furnaces, industrial heating processes such as heat treating and metal cutting, and vehicle fuel. Liquified compressed gases generally are those which become liquids in containers at ordinary temperatures at pressures from 25 to 2500 psig. As an example, the pressure of liquid propane at 70° F. (21.1° C.) is approximately 110-125 psig (756.4 KiloPascal KPa).
Liquified compressed gases are categorized as hazardous materials. Those who transport compressed gases must comply with a variety of government safety regulations in the United States, Canada and other countries throughout the world. Liquified compressed gases are shipped under rules that limit the maximum amount that can be put into a container to allow space for liquid expansion. For example, in the United States, a cargo tank (defined as a tank permanently attached to or forming a part of a motor vehicle) selected for transporting a specific compressed gas must be a container authorized for that S product and the container must be qualified with Department of Transportation (DOT) regulations. These regulations are contained in Title 49 of the Code of Federal Regulations, Parts 100 to 199.
Additionally, with flammable gases, it is necessary to guard against the possibility of fire or explosion. For example, when liquid propane is released into the atmosphere, it quickly vaporizes into its normal non-pressurized gaseous form. The propane combines rapidly with air to form fuel-air mixtures which are ignitable over a range of 2.2 to 9.5% by volume.
In the liquified compressed gas industry, transportation between the producer and the consumer is important. In many instances, the producer and consumer are separated by considerable distances. Large quantities of compressed gas must be transported over long distances by safe and economical methods. Liquified compressed gases are often transported in special tank cars, motor trucks, boat and train facilities.
For example, the propane industry in the U.S. transports between 7 and 10 billion gallons annually in highway transport vehicles to storage sites. The same volume is transported again from storage sites in local delivery bobtail trucks to storage containers.
Cargo tank motor vehicles have been developed to transfer liquified compressed gases. Two basic types are well known. Cargo tank motor vehicles known as “highway transports” are large cargo tanks mounted on semi trailers pulled by a highway truck tractor. A typical transport may carry 9000-16000 gallons of liquid. Cargo tanks must comply with DOT Specification MC-330 or MC-331. Smaller cargo tank motor vehicles, known as “bobtails”, are cargo tanks mounted directly on a vehicle chassis. A bobtail may carry up to 5000 gallons of liquid.
In each type, a pump on the vehicle is powered by the vehicle engine, meaning that the engine must remain on during unloading.
In the case of highway transports, liquified compressed gas is transferred from the highway transport to a storage container by means of a hose. A pump is mounted on the highway transport to move the liquified gas from the cargo tank, through the hose and into the storage container. A pump valve is located on the highway transport between the cargo tank and the pump. The pump valve may be operated manually by the operator or may have an automatic feature that will close the valve in the event of a drop in the pressure.
In the case of bobtails, liquified compressed gas is transferred from the bobtail storage tank to a storage container by means of a hose.
Notwithstanding the foregoing, the existing vehicle belly valve may not be automatically activated in the event of a rupture, a severing or uncoupling of the hose. Most recently, the U.S. Department of Transportation has announced proposed rules and interim rules relating to emergency discharge control systems on cargo tanks (see, for example, 49 CFR §178).
For these reasons, there still remains a need for an automatic safety shutoff system in the event of a rupture, severing or uncoupling of a delivery hose between a cargo tank vehicle and a storage container.
It is, therefore, a principal object and purpose of the present invention to provide an automatic safety shut off system in the event of a rupture, severing, or uncoupling of a delivery hose between a cargo tank vehicle and a storage container.
SUMMARY OF THE INVENTION
The present invention is directed to the transfer of pressurized fluid between a cargo tank vehicle and a storage container. A cargo tank vehicle includes a cargo tank to store pressurized fluids, such as liquid propane. An engine not only powers the vehicle but includes a power take off that will power a pump or compressor. A belly valve mounted on the vehicle is in fluid communication with the cargo tank and in fluid communication with the pump. The belly valve includes a normally closed moveable butterfly plate. When the valve is closed, no pressurized fluid can pass between the cargo tank and the pump.
Outflow from the pump is connected to a delivery hose. The delivery hose has a first end in fluid communication with the pump and its coupling. The delivery hose also has a second end in fluid communication with the storage container. Near the hose second end, a hose coupling includes an opening therethrough to which will be attached a small pressure hose in fluid communication with the pressurized fluid. The pressure hose leads back to a first pressure sensor which can detect a drop in pressure and de-energize a set of electrical contacts. The first pressure sensor is connected to a first switch. The first switch will activate or deactivate a supply solenoid and supply valve and a bleed solenoid and bleed valve. The supply and bleed valves are in line with the air pressure system of the vehicle which operates the belly valve.
Near the hose first end, in fluid communication with the pump, the coupling includes an opening to which will be attached a small pressure hose in fluid communication with the pressurized fluid in the delivery hose. The pressure hose leads back to a second pressure sensor which can detect a drop in pressure and de-energize a set of electrical contacts. The second sensor is, in turn, connected to a second switch. The second switch will activate or deactive the supply and bleed solenoids and valves.
A further, additional mechanical safety mechanism may be employed. Accompanying and attached to the delivery hose is a thin, steel cable. The cable may be attached at periodic intervals to the delivery hose or, alternatively, may be formed integrally with the delivery hose. The cable has a first end . terminating in a pin receivable in a switch receptacle on the control box. The switch receptacle is likewise wired to the supply and bleed valves. When the pin is retracted or disengaged, the belly valve will be closed. The cable has a second end which is connected to an eyelet attached to the storage container. A rupture, severing, or uncoupling of the delivery hose will cause deflection of the hose. Deflection of the delivery hose will cause the pin to retract or become disengaged from the switch receptacle. Accordingly, the supply and bleed valves will cause the belly valve to close, preventing additional pressurized fluid from escaping from the storage tank of the vehicle.
REFERENCES:
patent: 2773251 (1956-12-01), Snyder
p
Head Johnson & Kachigian
Mapco, Inc.
Rivell John
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