Communications: electrical – Condition responsive indicating system – Specific condition
Reexamination Certificate
2003-01-31
2004-09-07
Wu, Daniel J. (Department: 2632)
Communications: electrical
Condition responsive indicating system
Specific condition
C340S577000, C340S578000, C340S587000, C340S588000, C340S589000, C340S286050, C340S289000, C340S304000, C340S628000, C340S629000, C340S630000
Reexamination Certificate
active
06788208
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATIONS
Applicant claims priority under 35 U.S.C. §119 of German Application No. 102 04 384.1 filed Feb. 4, 2002.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for controlling stationary fire-extinguishing systems, and in particular for controlling fire-extinguishing installations that are operated with liquid or gaseous fire-extinguishing agents. In addition to the fire-extinguishing devices which dispense liquid or gaseous fire-extinguishing agents, the important components of stationary fire-extinguishing systems are the fire alarm devices for controlling fire-extinguishing installations. Such fire-alarm devices are in the center of the present invention.
2. The Prior Art
Fire-extinguishing systems include a reservoir of fire-extinguishing liquid or gaseous agents that is connected with a monitored area (building, warehouse, etc.) via a more or less branched system of pipelines. In the event of a fire, the extinguishing agents are released by means of fire-extinguishing nozzles. The nozzles are arranged in accordance with the specific fire-extinguishing task on hand.
Depending on the type of fire hazard involved and the areas that have to be protected, widely branched sprinkler systems or fine-spray fire extinguishing systems are employed that produce a highly effective water mist. Also gas fire-extinguishing systems may be used which operate with an inert gas such as carbon dioxide as the fire-extinguishing agent.
To fight a fire effectively, the point or points at which the various types of fire-extinguishing systems are triggered plays a special role.
This task is assumed by fire-alarm systems that, in most cases, are equipped with detectors for an early detection of various fire identification characteristics.
Such fire-alarm systems include one or more detectors that are accommodated in fire-alarm devices. The devices are often connected with a fire-alarm center via signal lines (fire alarm lines).
Fire-alarm installations are in most cases built from a great number of sturdy fire-alarm devices.
The detectors react to the occurrence or change in measurable fire identification characteristics such as the temperature, the radiation, particulate matter (aerosols), or gases characterizing a fire.
In the fire alarm center, the measurement signals received from the fire-alarm devices installed in the monitored areas of the fire-extinguishing system are processed, and, in the event of an alarm, corresponding control commands are transmitted to the fire-extinguishing system.
All physical or chemical changes of condition parameters occurring in the area monitored by a fire-alarm system that are caused by a fire and can be detected by means of sensor elements or detectors are summarized herein under the term “fire identification characteristics”.
Thus the fire identification characteristics are condition parameters of the fire. These parameters include, for example, the ambient temperature, the composition of the gas (smoldering or combustion gases), the density of optically detectable smoke or soot particles (aerosols), and the electromagnetic radiation emitted by fires on different wavelengths.
Stationary fire-extinguishing systems are successfully employed for fire-fighting purposes in many areas of fire protection in buildings, equipment installations, or in the area of warehousing of materials.
It is known that the fire-extinguishing process is triggered and the fire-extinguishing agents are released by automatically operating fire-alarm devices.
So that the start of a fire can be detected early, the fire-alarm devices should be installed as closely as possible to a site where a fire may possibly originate, on the one hand. On the other hand, however, the local circumstances have to be taken into account as well.
In this connection, in addition to the early detection of fires, the prevention of false fire alarms as well is the focus of the further development of fire-alarm devices.
False fire alarms are frequently triggered by uncritical parameters or processing process-conditioned sources. A rise in the temperature within the vicinity of a heat-alarm device that cannot be attributed to the start of a fire may lead to a false alarm as well.
With many conventional fire-extinguishing systems, the entire supply of fire-extinguishing agents is often consumed without interruption after a fire alarm has been triggered and the extinguishing process has been activated.
However, such extensive fire-extinguishing measures are normally not required in connection with smaller, locally confined fires.
False alarms cause even greater damage: not only will the consumed supplies of fire-extinguishing agent (CO
2
-gas), which are available only to a limited extent in connection with certain fire-extinguishing systems, need to be replaced at high cost and with great expenditure of time, but also the fire-extinguishing agents unnecessarily dispensed may cause damage to persons and equipment, or may shut down entire manufacturing areas.
Numerous proposals have been made for resolving these known problems associated with the operation of stationary fire-extinguishing installations.
DE 100 12 705 A1 discloses a method and a device for the early detection and fighting of fire in indoor and outdoor areas, in particular in the area of residential houses and of buildings. The system includes a fire-extinguishing device and a fire alarm system that has one or more fire alarm devices with at least one detector. The detectors detect the same or different fire identification characteristics and trigger a fire-alarm signal after one or more pre-adjustable alarm thresholds of the detected fire identification characteristics have been exceeded. This fire-alarm signal then activates the fire-extinguishing system.
A method and a system for detecting fire in a monitored room (or space) with the possibility of increasing the sensitivity of the detector system are known from DE 41 42 419 A1. An undefined number of detectors are switched with respect to their sensitivity, and the number of detectors to be switched over is adapted to the further development of the fire.
A method for automatically reporting and extinguishing fires is known from DE 23 44 908 C2. In this process, the fire-extinguishing system is controlled and actuated only after a flame report is available. This report has to be preceded by two smoke reports and one heat report. The continuing presence of flames has to be tested in this connection at defined time intervals by a flame-reporting alarm device, and the dispensation of the fire-extinguishing agent either has to be maintained or shut down. However, it is not stated how exactly this testing procedure is carried out. The aim of this known method is to prevent false alarms and damage caused by any unnecessary influence of fire-extinguishing agent.
A similar fire-extinguishing method is described in DE 196 27 353 C1. In this method, the development of the fire is detected by sensors distributed over the room and the fire-extinguishing agent is dispensed in a manner adapted according to the development of the fire in terms of space.
DE 199 52 327 A1 discloses a fire sensor and a method for detecting a fire as well. The smoke signal emitted by the fire sensor is additionally corrected by correlating actual outside temperature and the rate at which the temperature is rising.
The purpose of such a correction is to adapt the smoke detection sensitivity of the sensor to the ambient temperature and the rate at which the ambient temperature is changing.
The probability of a false alarm is expected to be reduced by this method, and early triggering of the alarm is said to be achievable at the same time.
However, this patent document relates to the detection of fires only up to the activation of the fire-extinguishing system and contains no reference to the fire-extinguishing process and the control of the fire-extinguishing system after the alarm has been triggered.
The known fire-extinguishing systems have the drawbac
Minimax GmbH
Walk Samuel J.
Wu Daniel J.
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