Switch cabinet with a fire extinguishing system

Details Switch cabinet with a fire extinguishing system Switch cabinet with a fire extinguishing system

1999-09-10

2001-11-13

Mullen, Thomas (Department: 2632)

Communications: electrical

Condition responsive indicating system

Specified housing

C169S046000, C340S289000, C340S693600

Reexamination Certificate

active

06317053

ABSTRACT:

BACKGROUND OF THE INVENTION
The invention concerns a switch cabinet for servers and similar devices, particularly parts of sensitive computer devices, whose interior area is connected to gas bottles containing fire extinguishing gas and is continuously supplied with fresh air via a ventilator, with early fire detection sensors being switched into the exhaust air current outside of the interior area and the connection being activated in case of fire.
Switch cabinets serve the purpose of housing equipment and devices with which entire systems or groups of machines can be controlled and operated. Suitable switch cabinets can also house servers and other highly sensitive computer devices to which access by unauthorized personnel is to be denied and which, at the same time, are to be protected from other influencing factors, sometimes even of climatic kind. Beyond this, it is known to install in switch cabinets appropriate devices and equipment that can auto ignite and thus place themselves, but also their environment, at risk. Attempts are made to deoxidize the possibly occurring flame with inert gas. Appropriate switch cabinets and similar devices, however, have so far not been able to conquer the market due to the extensive amount of work that is involved.
From DE-OS 34 33 459, a device for early detection of fires and of overheating on housings and cabinets that enclose electric or electronic systems is known. For this, smoke detection occurs immediately at the air exhaust vent of the unit that is being monitored, e.g. with the help of an intake funnel. It also presents a device used to monitor electric equipment with regard to fire protection. FR 523 455 describes a switching system for a combined smoke alarm and fire extinguishing unit, which however unfortunately releases a fire-extinguishing agent, preventing the devices installed in the cabinet from being used any further. EP 459 944 suggests the utilization of carbon dioxide as a fire-extinguishing agent in order to be able to effectively handle only the system affected by the fire and thus limit fire and extinguishing damage to a minimum. For this, a fire detector is provided for in the warm air current of the system that is to be protected as well as an outlet orifice of the container with the fire-extinguishing agent within the housing of the system. With this design, however, lacking reliability of this control system proved to be disadvantageous because no samples are actively collected and no prompt or satisfactory fire-extinguishing procedure occurs in case of fire. Generated smoke reaches the fire detectors more or less by accident, which then triggers the release of carbon dioxide. The carbon dioxide then pushes oxygen out of the system through orifices until the flame has been extinguished. Subsequent fires cannot be prevented.
SUMMARY OF THE INVENTION
The invention is therefore based on the task of creating a switch cabinet that protects a server or similar highly sensitive computer parts and which ensures that, in case of fire in the interior, the fire is extinguished in a manner that is neutral or protective to stored data, occurs autonomously and reliably, and that at the same time prevents subsequent fires from flaring up.
According to the invention, the task is resolved by the fact that the interior is represented by a protective cabinet that is closed off from the atmosphere, that the gas bottles which are activated via the early fire detection sensors in case of fire are filled with the noble gas argon, that the interior is connected to the atmosphere via a supply tube which is equipped with an intake and exhaust air nozzle combination with screen on the end located outside the protective cabinet, and that the early fire detection sensors and the entire control system are assigned to an additional cabinet that is allocated to the protective cabinet.
This offers the opportunity of monitoring the protected switch cabinet continuously and to flood it fully automatically in the case of fire with a quenching gas, i.e. preferably with a harmless inert gas that does not pollute the environment. Due to the early fire detection sensors and the appropriate control system, the fire-inhibitory atmosphere can be maintained for a certain period of time, e.g. 20 minutes, so that by the end of that time period the fire can certainly be extinguished and the cabinet can subsequently be entered or inspected for repairs. The quenching gas argon that is utilized is generally recognized as being completely safe as a normal component of the atmosphere, but contrary to other gases offers the great advantage of eliminating cold shock, which is generated with other gases such as carbon dioxide. The highly sensitive electronic components installed in the area that is to be extinguished are therefore affected neither by moisture nor by a change in temperature during the extinguishing procedure. In this way, a beneficial double-effect is achieved, apart from the fact that the continuous feeding of fresh air during normal operation offers the benefit of maintaining a certain temperature within the switch cabinet so that negative influencing factors on the highly sensitive electronic components cannot occur even during operation. Additionally, it proves advantageous that areas of the systems which are not affected by the fire remain functional. With appropriate controls, exactly those parts that enable immediate start-up upon quenching or extinguishing of the fire can be operated. And finally it proves beneficial that the rooms in which the switch cabinets are installed remain accessible to employees.
A particularly compact version of an appropriately secured switch cabinet is possible if the early fire detection sensors and the entire control system are assigned to the protective cabinet. This additional cabinet can then be arranged in such a way that both air supply as well as air outlets are particularly pleasant for employees; however, a very compact design is especially possible when the additional cabinet has been adjusted to the upper part of the protective cabinet, and also houses the ventilator and is connected to the upper part. This design furthermore offers the advantage of easy retrofitting because only a few bores have to installed into the wall for the wires and tubes, which are required with regard to electronics as well as for air supply.
For recognition of a fire, only slight air supply or appropriate suction is required so that the ventilator does not require much space and only little energy. It is useful when the ventilator is set on suction during regular operation and stopped by the control system in case of fire. The connection, i.e. the line in the wall, would then be closed so that neither additional air can be sucked out through the ventilator nor can air enter through the orifice. Through appropriate control of the ventilator, the early fire detection sensors can be installed relatively close to the ventilator and thus outside the actual switch cabinet in order to be able to check air sucked out through the ventilator accordingly and to turn on appropriate units immediately, upon detection of fire.
A distinct feeding process of air sucked out through the ventilator occurs by connecting the interior with the atmosphere via a supply tube, with the tube being equipped with an intake and exhaust nozzle combination with screen at the end located outside the protective cabinet. During normal operation, the ventilator sucks air in through the intake nozzle, and the air is then guided into the lower a rea of the switch cabinet through the supply tube and flows upward from there. In doing so, it flows through practically all parts of the interior area, e.g. of the server, so that it carries possible traces of occurring fires to the outside of the switch cabinet already during their break-out phase, from where the early fire detection sensors are responsible for appropriate processing. At the same time, this intake nozzle can also be utilized as an air exhaust nozzle during fires because then the noble gas argon is

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