Disclosed is an automatic fire-extinguishing system comprising one or more portable automatic fire-extinguishers placed at desired locations within a region wherein automatic extinguishment should be effected when a fire occurs therein. Each of the fire-extinguishers includes integrally a bomb containing a fire-extinguishing gas under a pressure condition and a gas jetting nozzle connected through a valve to the bomb. At least one fire sensor is arranged at a desired location within the region. Each fire extinguisher is provided with an electro-mechanical means for opening the valve, an electrical means for actuating the opening means and an internal gas pressure detecting switch, and; an electric control circuit formed by the combination of the electric circuit of the opening means, electrical actuating means and the gas pressure detecting switch which are connected in series. If a plurality of fire extinguishers are utilized, the electric control circuits of these fire extinguishers are connected in series in such a way that the electrical actuating means of one fire extinguisher is capable of being actuated in response to a fire signal from the fire sensor while the electrical actuating means of the other fire extinguishers are capable of being actuated by an output signal of the internal gas pressure detecting switch of an adjacent upstream fire extinguisher.

An electrical protection system including a plurality of suppressor units each activatable by either a first or a second electrical current responsive activator to suppress abnormal condition. The system further includes a supervisory electrical current source, an activation electrical current source, a first connector circuit connecting all of the first activators in series and a second connector circuit connecting all of the second activators in series. A control circuit connects the supervisory source in parallel with the first and second connector circuits so as to provide in each a predetermined supervisory current that is insufficient to energize the activators. Included in the control circuit is an initiator device for selectively connecting the activation source to the first and second connector circuits so as to provide therethrough an activation current flow greater than the supervisory current flow and sufficient to energize the activators and thereby activate the suppressor units to suppress the abnormal conditions. Also included in the control circuit is a monitor system for monitoring the supervisory current flow through each of the first and second connector circuits.

There are described a method and a device for suppressing an explosion-like fire, in particular of hydrocarbons, by means of a fire extinguishing agent, which under pressure at a speed adapted to the speed of propagation of the fire is distributed in the space directly surrounding the source of the fire. To ensure an efficient fire fighting without adversely influencing the environment, it is proposed to spray water as fire extinguishing agent by atomizing the same to form a water mist in a minimum amount of 0.03 l/m.sup.3 from a water reservoir (3) in the space directly surrounding the source of the fire.

A fire extinguishing apparatus and an actuating system. The actuating system includes a plurality of actuators connected in parallel and a source of electrical signal for said actuators. Each actuator is connected in parallel with a device whose resistance decreases with increasing current through the device.

A fire and explosion suppression system which is operative for suppressing an explosion within 100 milliseconds of the existence of a high energy ignition and within 200 milliseconds of the existence of a low energy ignition. Actuation circuitry for this system is also disclosed and claimed and includes circuitry operative in two different modes having different sensitivities and response as well as circuitry for sensing the failure of suppression elements to operate and for actuation of additional suppression elements in response to this sensed failure.