5.3 Means for fire extinguishing

Primary means for fire extinguishing are:

• entrenching tool;

• fire extinguishers;

• manual fire equipment.

They all are placed on the special board. The board is set so that the distance to most remote, building wouldn't exceed 100 m, and to warehouses with flammable materials – 50 m, or set accounting one board per 5000 m².

The fire extinguishing means are painted in signal red color, and the inscriptions on them and on boards are made by contrast white color.

Fire extinguishers.

Water makes basic effect of extinguishing that's cooling of burning subjects down to temperature lower than combustion temperature. Water extinguishing flaws are: water freezing on negative temperatures; water doesn't extinguish combustible liquid with boiling temperature below 80°C; brings substantial damages for equipment and buildings; person extinguishing electrical equipment can be shocked; water badly moistens some filamentary and solid substances, therefore on their extinguishing water is not effective.

The foam can be chemical and air-mechanical. The chemical foam consists from pellets of carbon dioxide, air-mechanical contains air ones. Foam extinguishing effect is cooling of the upper layer and isolation of burning subjects from the atmospheric air. The foam is not applied for extinguishing of electrical equipment under voltage and such active substances as potassium, natrium, carbon bisulfide it reacts with.

Carbon dioxide (C0₂) is used, generally for extinguishing of electrical equipment. It's not applicable to extinguish ethyl alcohol, it's dissolved in, and also celluloid, thermit combustible without air.

Carbon dioxide extinguishing in closed rooms increases concentration of C0₂ dangerous for life.

Powder. The powder cloud creates protection from heat radiation, therefore fire can be extinguished without special protective cloth. When powder gets on the heated subjects there's saline decomposition and incombustible gases extraction happening what enhance extinguishing effect of powder. However, in the closed rooms on powder extinguishing high dust content in the air appears, the powders also have weak cooling effect that makes possible repeated inflaming.

5.4 Fire signaling and communication system

For communication on fire the telephone, radio, wireless telephone, devices of automatic and manual-automatic communication are applied. For warning people in rooms the special system of communication, internal wireless network and also beeps can be used.

Automatic signaling system. Main structure elements of the system are: transducers which are installed in building or on territory of an object and are for making a signal on fire; detection station to receive signals from transducers; communication lines, which connect transducers with detectors; power supply.

By principle of operation the transducers are divided into thermal, smoke, light, combined.

The thermal transducers respond to increase of environmental temperature and in turn are divided into maximum ones to turn on when temperature is increased to critical level; differential - turn on when environmental temperature increases with the certain velocity; maximum - differential.

Smoke transducers are divided into ionization and photoelectric. Smoke transducers can't be set in rooms with air temperature below – 30°C and above 60°C, relative humidity higher than 80 %, and also in very dusty rooms and areas where acid vapors can be.

The light transducers respond to ultra-violet or infra-red radiation.

Combined transducers are based on principles of operation of both thermal and smock transducers.

The signals from transducers come to:

• detection stations of fire signaling system;

• automatic means for fire extinguishing.