Fire extinguishers – Fluid systems – Distributing systems
Reexamination Certificate
2000-01-10
2001-08-28
Scherbel, David A. (Department: 3752)
Fire extinguishers
Fluid systems
Distributing systems
C169S037000, C169S005000, C169S019000, C169S020000
Reexamination Certificate
active
06279663
ABSTRACT:
BACKGROUND OF INVENTION
The invention relates to a nozzle, preferably for use in sprinklers and spray heads, for spraying medium, the nozzle comprising a housing, an inlet end and a first conduit leading from the inlet end to a nozzle opening to enable the spraying of the medium through the nozzle.
The invention also relates to a fire fighting installation comprising a number of sprinklers or spray heads, including nozzles, each nozzle comprising a housing, an inlet end and a first conduit leading from the inlet end to a nozzle opening for spraying medium through the nozzle, the sprinklers or spray heads being arranged to be activated depending on the location of the fire so that only some of the sprinklers or spray heads are activated at the beginning of the extinguishing process; and the installation also comprising a pressure source and lines for supplying the extinguishing medium to the sprinklers or spray heads.
The invention also relates to a fire fighting installation comprising a number of sprinklers or spray heads, including nozzles, each nozzle comprising a housing, an inlet end and a first conduit leading from the inlet end to a nozzle opening for spraying medium through the nozzle, the sprinklers and spray heads being arranged to be activated depending on the location of the fire so that only some of the sprinklers or spray heads are activated at the beginning of the extinguishing process; and the installation also comprising a pressure source comprising a pressure accumulator, and lines for supplying the extinguishing medium to the sprinklers or spray heads.
The flow of the medium, such as liquid, outlet from the nozzle is dependent on the pressure p which discharge the medium through the nozzle.
The dependence is such that the quantity Q of flow fulfils the formula Q=K{square root over (p)}, where K is the resistance of the nozzle. The K value depends on the diameter d of the nozzle opening in accordance with the formula K=0.78 d
2
, when the opening is a so-called short opening. From the above formulae it is apparent that the flow will not increase much when the pressure rises and the K value is constant. In some applications, for example in fire fighting, a great increase in the flow is desirable when the pressure rises, as will be understood from the following.
The fire fighting systems are usually designed to cover a defined area or large space. On the land base applications the basis of design is an area of 205 m
2
, which requires 15 sprinklers. The drive or pressure units of the fire fighting systems are designed in accordance with the area or space so that a desired pressure and flow of water are achieved for the area to be covered. In the case of a sprinkler system in which the sprinklers and/or spray heads are activated by heat either individually or in groups, the fire can usually be brought under control even with only a few of the spray heads or sprinklers necessitated by the design. The controlling of the fire means that it cannot spread. The fire can usually be brought under control with two sprinklers, whereby it is not necessary for any more sprinklers to be activated. Even when the fire is under control, however, it continues to burn and produce a notable amount of smoke and gas. The flue gases can be very toxic and even kill people; in addition, the smoke hampers the visibility and thereby hinders the firemen in their work. In situations like this, only a fraction of the fire fighting power of the drive or pressure units of the fire extinguishing systems are used, which can be shown by calculations. The power P used is directly proportional to the flow Q and pressure p and inversely proportional to the efficiency of the drive unit.
The pressure unit of the fire fighting installation is designed so that a predefined flow of water with a predefined pressure is achieved in the area to be covered. If, for example, the area requires 15 sprinklers and the flow of a sprinkler is 13 l/min at a pressure of 60 bar, the total flow of the fire fighting installation is 195 l/min when all the sprinklers have been activated. When the loss of pressure in the lines is 20 bar and the efficiency is 0.85, the power demand in the pressure unit is 30 kW. If only two sprinklers are activated, only 13% of the power is used, i.e. about 4 kW. The K value of the nozzle is here 1.7, and the efficiency is 60%.
The drawback in the previously known fire fighting installations is that only part of the power of the pressure unit is used for extinguishing the fire when only some of the nozzles of the fire fighting installation are activated. Consequently, the fire cannot often be extinguished immediately. In order that the fire could always be extinguished as quickly as possible, very expensive systems would have to be used.
BRIEF DESCRIPTION OF INVENTION
An object of the invention is to provide a nozzle in which the flow increases heavily as the pressure rises.
Another object of the invention is to provide a fairly simple fire fighting installation that enables the delivery of a large amount of extinguishing medium to the fire area at the very beginning of the extinguishing process even when only some of the spray heads and nozzles of the fire fighting installation are activated, whereby a large amount of extinguishing medium is delivered to the fire area immediately. The arrangement allows the maximum fire fighting capacity to be used from the very beginning, and so the fire can often be extinguished immediately.
In order that the full power of the drive unit of the fire fighting installation could be used, the pressure should be raised up to about 290 bar in accordance with the formula presented above, if only two conventional nozzles, i.e. nozzles whose K value is constant, are activated. The flow is then about 29 l/min per nozzle. It is not, however, economically sensible to raise the pressure so much, and even if it is raised, the flow will not increase sufficiently.
The fire fighting installation of the invention comprises sprinklers or spray heads with such a structure that the K value of the nozzles is not constant but changes with the pressure within a certain pressure range. The arrangement enables a strong flow and efficient use of the fire fighting installation at the very beginning of the extinguishing process, even though only some of the sprinklers or spray heads have been activated. As usual, the basis of design of the fire fighting installation is the controlling of the fire when all the sprinklers or spray heads necessitated by the design have been activated.
When the fire fighting installation of the invention is used, the nozzles of the spray heads are, for example, such that their K value at 120 bar is 4.4. This means an about 49 l/min flow of water per nozzle when only two spray heads are activated. The flow is thus about 2.6-fold as compared with the situation when the K value 1.7. This kind of combination of water flow and pressure means that the power of the pressure unit is about 27 kW when there are two nozzles, the losses of pressure in the lines are 20 bar, and the efficiency of a pump unit is 0.85. If all the 15 sprinklers are activated, the pressure will drop to 60 bar, and the flow will be 13 l/min per nozzle, which is needed to control the area. When the pressure drops from 120 bar, the efficiency of the pressure unit remains almost constant, unlike in the previously known fire fighting installations.
A nozzle of the invention is characterized by comprising a second conduit for spraying the medium through the nozzle, a valve element loaded by a spring being arranged in the conduit so as to keep the second conduit closed when the valve element is subjected to a first pressure by said extinguishing medium, and the valve element being arranged to open said second conduit when the valve element is subjected to a second pressure by said extinguishing medium, and the second pressure being higher than the first pressure. The preferred embodiments of the nozzle of the invention are described in attached claims
2
to
8
.
The fire fighti
Evans Robin O.
Ladas & Parry
Scherbel David A.
LandOfFree
Nozzle and fire fighting installation does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Nozzle and fire fighting installation, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Nozzle and fire fighting installation will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2478021