Fire extinguishers – Sprinkler heads
Reexamination Certificate
2000-05-26
2003-07-01
Evans, Robin O. (Department: 3752)
Fire extinguishers
Sprinkler heads
C169S038000, C169S040000, C169S041000, C169S042000, C169S056000, C169S057000, C169S058000, C169S059000, C169S060000
Reexamination Certificate
active
06585054
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to sprinklers used in automatic fire extinguisher systems for buildings and the like, and in particular, relates to a fast response sprinkler head and fire sprinkler system for use in environments wherein one or more obstructions are positioned in proximity to the sprinkler head.
Automatic sprinklers have long been used in automatic fire extinguishing systems for buildings in order to disburse a fluid to control a fire. Typically, the fluid utilized in such systems is water, although systems have also been developed to disburse foam and other materials. Historically, sprinkler heads include a solid metal base connected to a pressurized supply of water, and some type of deflector used to alter the trajectory of the water flow. Alteration of the water flow by the deflector generates a defined spray distribution pattern over the protected area. The deflector is typically spaced from the outlet of the base by a frame, and a fusible trigger assembly secures a seal over the central orifice. When the temperature surrounding the sprinkler head is elevated to a pre-selected value indicative of a fire, the fusible trigger assembly releases the seal and water flow is initiated through the sprinkler head.
Fire extinguishing sprinkler heads come in three general structural types, namely, upright, pendent and sidewall. Of interest to the present application are the pendent type and, in particular, upright structural type. Pendent sprinklers depend below a fire extinguishing fluid supply pipe, such as a water pipe. In pendent sprinklers, when the fusible trigger assembly reaches a pre-selected temperature due to the presence of fire, the fusible trigger assembly releases the seal positioned over the outlet, enabling water to flow through the central orifice of the sprinkler head in a downward direction. As the water exits from the sprinkler head, it is typically disbursed by the deflector which alters the trajectory of the water so as to define a spray distribution pattern in an attempt to control the fire.
An upright sprinkler differs from a pendent sprinkler in that it projects upwardly from the fluid supply pipe. When an upright sprinkler is activated, the water flows upward through the sprinkler head and is expelled from the central orifice in an upward direction. Gravitational forces, in combination with the deflector spaced a pre-selected distance above the central orifice, results in the formation of a downwardly. moving spray distribution pattern in an attempt to control a fire. In addition to some common benefits and advantages, pendent and upright sprinklers each have some benefits relative to the other type. Upright sprinklers for example, have less of a tendency to collect contaminant build-up since the containments settle down into the branch pipe and thus potential blockage is reduced.
Historically, automatic sprinkler systems have been designed to achieve what is referred to as “fire control” about a protected area. In the fire control method of combating fires, the automatic sprinkler system is designed and installed such that a relatively large number of individual sprinklers will activate upon detection of a fire. That is, in response to a fire, not only will the sprinklers closest to the fire be actuated, but also sprinklers which protect the areas surrounding the fire, so as to define a controlled area. While it is anticipated that the sprinklers immediately above the fire may not be able to extinguish the fire, the goal of the fire control method is to actuate the sprinklers about the fire to pre-wet the combustible materials in the fire's general vicinity to prohibit the fire's growth. Thus, the fire control method seeks to confine the fire within a predetermined area until additional fire fighting methods are deployed, such as response by a fire department, in order to extinguish the fire.
Beginning in the 1970's, industries began more widely using relatively large warehouses for the storage of product. To effectively utilize space within these warehouses, product is normally stacked on pallets or racks in a vertical arrangement. These warehouses may reach approximately 30 feet in height and contain stacked pallets as high as approximately 25 feet. Traditional sprinklers, designed and installed so as to provide “fire control,” have proven ineffective in combating fires ignited in these large warehouses. As the vertically stacked pallets may exceed over twenty feet in height, fires ignited within these pallets produce a plume of combustion gasses which rapidly travels upward and subsequently impacts the ceiling of the warehouse. The rapid generation of these combustion gases creates a zone of high temperature above the fire, and thus when the sprinkler head is activated, an unacceptable quantity of water expelled from the sprinkler is evaporated within this high temperature zone before it reaches the site of the fire. As a result, less water is actually delivered to the fire and hence prevents effective fire control.
After impacting the ceiling, these combustion gases span out in a horizontal direction along the surface of the ceiling. The rapid movement of the combustion gases along the ceiling results in the actuation of a large number of sprinkler heads located a remote distance from the perimeter of the fire. The mass actuation of sprinkler heads within the warehouse produces several unacceptable consequences. First, the near simultaneous actuation of a large number of sprinkler heads produces a significant decrease in the water pressure delivered to each individual sprinkler head. Consequently, less water is available for delivery to the fire and thereby provides an opportunity for the fire to spread. Furthermore, actuation of remotely located sprinkler heads results in water damage to the product protected by such sprinklers.
In response to the inadequacies of existing sprinkler heads and the “fire control” deployment method, the sprinkler industry began the design and installation of “Early Suppression Fast Response” (hereinafter referred to as “ESFR”) sprinkler heads. As the name indicates, the theory behind ESFR is to deliver a sufficient quantity of water during the early stages of fire development in order to suppress and extinguish the fire and deny the opportunity for fire growth. In order to achieve the goal of early suppression, ESFR sprinklers must quickly generate a sufficient quantity of water capable of penetrating the fire plume and thus be delivered to the core of the fire, often referred to in the industry as the “fuel package.” To deliver a sufficient quantity of water to the “fuel package”, ESFR sprinklers are equipped with a thermally sensitive fusible trigger assembly capable of actuating the sprinkler head shortly after ignition of the fuel package. Normally, ESFR sprinklers utilize fusible trigger assemblies which have a fusing temperature between approximately 155° F. and 175° F.
To determine the ability of these ESFR sprinklers to suppress high challenge fires generated by industrial warehouses, the sprinkler industry, and in particular the Factory Mutual Research Corporation (hereinafter “FMRC”), developed the concepts of actual delivered density (hereinafter “ADD”), required delivered density (hereinafter “RDD”), and response time index (hereinafter “RTI”) as quantifiable measures of sprinkler performance. The RDD is the amount of water that must be delivered to a fuel package composed of a particular type of combustible material in order to achieve suppression. The establishment of a RDD value for a particular fuel package is achieved by various tests most oftenly conducted by the FMRC. The ADD value depends on the construction of the particular sprinkler head and is defined as the amount of water which is actually deposited onto the top of a combustible fuel package. Generally speaking, the RDD value increases as a function of time once ignition of the fuel package is initiated. During the maturation of the fire, the RDD increases as a function of time because as
Bosma Michael J.
Deegan Thomas G.
Dornbos Delwin G.
Franson Scott T.
Thomas Peter W.
Evans Robin O.
The Viking Corporation
Van Dyke Gardner, Linn & Burkhart, LLP
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