1. Field of the Invention
The present invention relates generally to the suppression of fires and, more particularly, to methods and apparatus for suppressing fires including the suppression of fires within human-occupied spaces and clean room-type environments.
2. State of the Art
Fire suppression systems may be employed in various situations and locations in an effort to quickly extinguish the undesirable outbreak of a fire and thereby prevent, or at least minimize, the damage caused by such a fire including damage to a building, various types of equipment, as well as injury or loss of human life. A conventional fire suppression system or apparatus may conventionally include a distribution apparatus, such as one or more nozzles, that deploys a fire-suppressing substance upon actuation of the system. Actuation of the system may be accomplished through means of a fire or smoke detection apparatus that is operatively coupled to the suppression system, through the triggering of a fire alarm, or through manual deployment. Various types of fire-suppressing substances or compositions may be utilized depending, for example, on where the fire suppression system or apparatus is being employed, how large of an area is to be serviced by the fire suppression system, and what type of fire is expected to be encountered and suppressed by the system.
For example, in some commercial and even residential fire suppression systems, a network of sprinklers is employed throughout the associated building and configured to distribute water or some other fire-suppressing liquid to specified locations within the building upon activation of the system.
However, a system providing a liquid fire suppressant is not suited for all situations. For example, it would not be generally desirable to employ a fire suppression system utilizing water as the suppressant in a location where grease would likely serve as fuel for an ignited fire at the given location. Similarly, it would not be generally desirable to utilize a liquid suppressant in a location which contained electrical equipment including, for example, costly and sensitive electronic or computer equipment. While a liquid suppressant might adequately suppress a fire in such a location, the suppressant would likely impose substantial damage to the equipment housed therein. Further, a liquid suppressant is not ideally suited for use in a clean room environment where the introduction of a liquid material to the clean room would result in contamination of some article of manufacture (e.g., an integrated circuit device).
Other available suppressants include dry chemical suppressants such as, for example, sodium bicarbonate, potassium bicarbonate, ammonium phosphate, and potassium chloride. While such suppressants can be effective in specific implementations, it is often difficult to implement systems which effectively utilize dry chemicals in large areas. Furthermore, use of dry chemicals can pose a health hazard to individuals in the vicinity of their deployment, as well as act as a source of contamination of electronic and computer equipment or even goods being manufactured, for example, in a clean room. Thus, such suppression systems are not conventionally utilized in locations such as clean rooms, computer rooms or spaces designed for human occupation.
Another type of suppressant which has been used includes gas suppressants. For example, gases designated generally as Halons have been effectively used as fire suppressants in the past. Halons include a class of brominated fluorocarbons derived from saturated hydrocarbons wherein the hydrogen atoms are essentially replaced with atoms of the halogen elements bromine, chlorine and/or fluorine. Halons, including the widely used varieties designated as Halon 1211, 1301 and 2402, have been used for the effective suppression of fires in various environments and situations including human-occupied and clean room-type environments. However, in recent years, an effort to phase out Halons has been undertaken due to their ozone depletion characteristics. Indeed, in the year 1994, production ceased of certain Halons, while others are scheduled to be phased out by the year 2010.
Some of the gases which have been used in an attempt to replace the effective Halon gases include, for example, nitrogen and carbon dioxide. Such gases essentially displace the oxygen contained within the air at the location of the fire such that an insufficient amount of oxygen is available for further combustion. However, such gases generally require the distribution of relatively large volumes of the selected gas in order to be effective as a fire suppressant. In order to accommodate such large volumes of gas, expensive and bulky pressure vessels are conventionally required to store the gas in a compressed state in anticipation of its use. Furthermore, such gases sometimes include or produce byproducts which may be harmful to any equipment or individuals located in the area into which the gas suppressant is distributed.
Additionally, as noted above, the requirements of storing gas, conventionally at high pressures and in large volumes, often make such systems expensive and cumbersome in size in that the systems require a significant amount of space available for installation and operation. In order to address some of the concerns listed above, including the ability to provide adequate volumes of suppressant while requiring relatively small storage facilities, various attempts have been made to develop alternative fire suppression systems.
Some of the approaches to provide alternative fire suppression systems include those disclosed by U.S. Pat. No. 6,257,341 to Bennett, U.S. Pat. No. 5,609,210 to Galbraith et al., and U.S. Pat. No. 6,401,487 to Kotliar. The Bennett Patent generally discloses a system which utilizes a combination of compressed inert gas and a solid propellant gas generator. Upon ignition, the solid propellant gas generator generates nitrogen, carbon dioxide, or a mixture thereof. The gas generated from the solid propellant is then mixed and blended with the stored compressed inert gas, which may include argon, carbon dioxide or a mixture thereof, to provide a resulting blended gas mixture for use as a suppressant. The Bennett system claims to provide a system which is smaller in size than prior art systems and, therefore, is more flexible in its installation in various environments. However, due to the fact that the Bennett system utilizes compressed inert gas, appropriate pressure vessels are required which, as discussed above, are conventionally expensive and require a substantial amount of space for their installation, particularly if a large room or area is being serviced by the described system, therefore requiring a large volume of suppressant.
The above-referenced Galbraith patent generally discloses, in one embodiment, a system which includes a gas generator charged with a combustive propellant wherein the propellant, upon ignition, generates a volume of gas. The generated gas is directed to a chamber containing a volume of packed powder such as magnesium carbonate. The gas drives the powder from the chamber for distribution of the powder onto a fire. In another embodiment, Galbraith discloses a system wherein the generated gas is used to vaporize a liquid, thereby generating a second gas, wherein the second gas is used as the fire suppressant. However, the use of powders, as noted above, is not desirable in, for example, areas which are intended for regular human occupancy, areas intended to house sensitive electronic equipment, or other clean room-type environments. The use of vaporizable liquids may introduce additional issues regarding long-term storage of the liquid including the prevention of possible corrosion of the associated storage container.
The above-referenced Kotliar patent generally discloses a system that includes a hypoxic generator configured to lower the oxygen content of the air contained within a room or other generally enclosed space to a level of approximately 12% to 17% oxygen. One of the embodiments disclosed by Kotliar includes a compressor having an inlet configured to receive a volume of ambient air from the room or enclosure. The compressed air is passed through a chiller or cooler and then through one or more molecular sieve beds. The molecular sieve bed may include a material containing zeolites that allows oxygen to pass through while adsorbing other gases. The oxygen that passes through the molecular sieve bed is discharged to a location external from the room or enclosure being protected. The molecular sieve bed is then depressurized such that the gases captured thereby are released back into the room as an oxygen-depleted gas.
While Kotliar discloses that the system may be used as a fire suppressant system, it is not apparent how efficient the system is in rapidly reducing the oxygen level for a given room so as to suppress any fire therein. Moreover, it appears that the Kotliar system is contemplated as being more effective as a fire prevention system wherein the hypoxic generator is continuously running such that the air within a room or other enclosure is continuously maintained at an oxygen-depleted level in order to prevent ignition and combustion of a fuel source in the first place. However, such an operation obviously requires the constant operation of a hypoxic generator and, thus, likely requires additional upkeep and maintenance of the system. Furthermore, while Kotliar asserts that there are no associated health risks to those who spend an extended amount of time in a hypoxic environment (i.e., an oxygen reduced or depleted environment), such a system may not be ideal for those with existing health conditions, including, for example, respiratory ailments such as asthma or bronchitis or cardiovascular conditions, or for individuals who are elderly or who generally lead an inactive lifestyle.
In view of the shortcomings in the art, it would be advantageous to provide a method, apparatus and system for suppressing fires that provide effective and efficient suppression of a fire within a given location while utilizing a suppressant that is not ozone-depleting yet is fit for use in rooms that are intended for human occupation or that house sensitive components and equipment. It would further be advantageous to provide such a method, apparatus and system that may be adapted for use in numerous locations and in a variety of applications without the need to utilize bulky and expensive storage equipment such as that associated with the storage of compressed gas or other liquid suppressants.