Refrigeration – Cryogenic treatment of gas or gas mixture – Separation of gas mixture
Reexamination Certificate
2002-02-19
2003-05-06
Capossela, Ronald (Department: 3744)
Refrigeration
Cryogenic treatment of gas or gas mixture
Separation of gas mixture
C062S078000, C062S260000, C169S045000, C169S064000, C454S166000, C454S167000
Reexamination Certificate
active
06557374
ABSTRACT:
FIELD OF THE INVENTION
The present invention introduces a fire suppression system for transportation tunnels and mines and methods of selective delivery of breathable fire-suppressive composition directly to the location affected by fire. The invented system is mostly suitable for installation in existing automobile and railroad tunnels without interruption of traffic. The system is also suited to provide complete fire safety in mines and other underground facilities, multilevel parking garages, industrial complexes, office and apartment buildings, schools, hospitals, shopping and entertainment centers and other enclosed compartments and environments.
This invention is an important addition and improvement of the Fire Prevention and Suppression Systems (FirePASS™) described in earlier patent applications provided above.
DESCRIPTION OF PRIOR ART
Tunnel fires have been usually divided into three types based on their order-of-magnitude rate of energy output. They are: small automobile fires (1 MW); medium fires (10 MW); and major and catastrophic fires (100 MW and higher). Small automobile fires are routine incidents, occurring as frequently as weekly in congested urban tunnels. Such reported fires have been universally extinguished without difficulty to date.
However, the catastrophic fire following a suicidal terrorist attack in a congested traffic tunnel remains to be the most critical scenario, for which emergency services and authorities are unequipped and unprepared. It is relatively uncomplicated to organize and carry out such attack. For instance a regular track can be used, loaded with flammable liquid canisters or pressurized propane gas containers. Such an attack can cause a significant initial structural damage with a consequent catastrophic fire and numerous fatalities.
Devastating tunnel fires demonstrate that their consequences depend entirely on the tunnel ventilation. Due to the necessity of providing adequate ventilation, a fire in a queue in an urban tunnel with a mixed fire load of passenger cars, buses and trucks could easily develop into catastrophe. Fire services will not be able to tackle these fires until it is too late, because radiant heat and smoke production is too great. This was the case in the last tunnel fire (October 2001, St-Gotthard tunnel), when firefighters could not even enter the tunnel until combustible materials were consumed by fire. Enhanced ventilation can also develop as a result of the chimney effect, as in the London Subway Fire and in the Kaprun disaster.
Current fire-preventative and fire-suppressive methods are totally insufficient in dealing with catastrophic tunnel fires. Several systems, either installed or contemplated—aside from their effectiveness during normal operations—show little capability of satisfactory operation during a catastrophic fire emergency. These are fire extinguishers, stand pipes, and sprinklers (including water mist sprinklers) with their ancillary systems of water supply and drainage, and different types of ventilation. The standard safety-supporting systems (communication, ventilation, lighting, and escape), primarily support the comfort and well-being of persons in a tunnel during normal operations, but their functions during catastrophic events are insufficient, as was revealed in the Channel Tunnel fire in 1996.
Automatic fire suppression systems based on water mist may be of little benefit in preventing structural damage to a tunnel and will not be effective in reducing loss of life in the event of a terrorist act followed by a catastrophic tunnel fire. The fire will probably be fully developed before the suppression system would be activated. The explosion can damage the water pipe system before it can create sufficient pressure for sprinklers. There will be a time lag between fire ignition and the activation of the water suppression system, which, in cold climates, must be initially dry. It will take time until pumps are started, valves are opened, and the delivery system piping is filled with water. Vehicular tunnel conditions cannot exploit sprinkler or water mist system strengths and turn most of them to a disadvantage. Tunnels are very long and narrow, often sloped laterally and longitudinally, vigorously ventilated, and never subdivided, so heat will normally not be localized over a fire. A catastrophic, hazardous-material fire will grow and spread hot combustion products far from its origin before sprinkler heads open, especially in colder regions where the water-suppression system is by necessity a dry one.
An inordinately large flow of water would be required to deliver an effective spray through all the potentially-open heads to assure application upon the fire itself. Besides that, since the fires usually originate from the lower part of a vehicle there will be no efficient fire suppression from sprinklers placed on the ceiling or walls of a tunnel.
Automatic activation of the sprinklers by active detectors would of necessity be delayed until all traffic could be halted, since even light spray would catch drivers unaware, and would dangerously slicken the roadway. Water squirting from the ceiling of a subaqueous tunnel would suggest tunnel failure and induce panic in motorists. Inadvertent activation is clearly unacceptable. Moreover, discharging water onto a fully developed catastrophic fire within an enclosed tunnel may only increase the danger to the tunnel occupants because of the steam generated when water contacts the fire.
Available publications and statistical data clearly indicate that currently no adequate and reliable fire-preventative and fire-suppressing technology for traffic tunnels is available anywhere in the world.
The new fire-safety technology, FirePASS™ (Fire Prevention And Suppression System), recently developed by the inventor and described in previous patent applications provided above, can help resolve the complex problem of fire safety in transportation tunnels, as well as in normally occupied facilities in general. FirePASS™ can minimize structural damage and fatalities in terrorist attacks. This system is effective in the prevention and instant extinguishing of fire of any possible origin and size. It is also absolutely safe for people and is user-friendly, while completely excluding any damage of equipment and property.
The system can be referred as related to Total Flood Clean Agent Systems, but it has significant differences from them. The FirePASS™ works by creating a safe human-breathable atmosphere in which nothing can be ignited or burn. This technology employs the Normobaric Breathable Hypoxic Air (NBHA) for prevention and suppression of fire.
FirePASS technology for tunnels is based on two properties that differentiate it from all other total flood clean agent systems:
1. The hypoxic generator produces oxygen-reduced air with a preset fire-suppressive, but safe for human breathing, concentration of oxygen. This eliminates the necessity of oxygen monitoring to control the tunnel atmosphere within the range of preset parameters. It also eliminates the complicated and vulnerable electronic feedback circuits that are sensible to structural and fire-related damage.
2. When in use, the protected space is constantly ventilated with fire-suppressive, breathable hypoxic air. This creates normal or even improved hygienic conditions for occupants of the tunnel while the hypoxic generator produces HEPA-filtered, normal-humidity air. Constant ventilation allows the prompt evacuation of toxic combustion gases without feeding fire with oxygen, which is not possible by any prior art systems.
As a fire-preventive modality, the environment of normobaric breathable hypoxic air in normally occupied facilities, including railroad tunnels, entirely eliminates the possibility of ignition of all common inflammable materials. As a fire-extinguishing option the effluent discharge of breathable hypoxic air would eliminate fire of any size and origin in seconds, while simultaneously evacuating toxic combustion gases and providing people with fresh breathable air. Smoke evacuat
Capossela Ronald
FirePASS Corp.
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