General firefighting and suppression system equipment description and operation

A description and operation of different types of fire suppression components and systems and fire detection components is presented in the following paragraphs.

1. Dry pipe sprinkler system. Dry pipe sprinkler systems have heat operated fusible sprinkler heads similar to a wet pipe system, however, the piping system contains air under pressure. When a sprinkler head fusible link melts, the air pressure is reduced, a “dry pipe” valve in the riser is opened by water pressure and water flows to any opened sprinkler heads. A small air compressor is required for this system.
2. Deluge sprinkler system A deluge type of fire suppression system consists of open-type sprinkler heads attached to a network of dry (not water-filled) piping which is automatically controlled by a fully supervised fire detection system which also serves as a fire alarm system. When a fire is detected, an automatic deluge valve is tripped open, admitting water to the system for discharge through all sprinkler heads.
3. Pre-action sprinkler system. The pre-action type of sprinkler system is similar to the above water spray deluge system except that it contains fusible link sprinkler heads. When the supervisory system opens the valve, water will flow through those sprinklers whose fixed temperature elements and fuses have been opened by the heat from a fire.
4. Carbon dioxide (CO2) fire suppression system. A CO2 fire suppression system usually consists of a trailer mounted low pressure refrigerated liquid CO2 storage tank with temperature sensing controls to permit the automatic injection of piped CO2 into areas to be protected. The system usually includes warning alarms to alert personnel whenever CO2 is being injected into an actuated area. CO2 will displace all oxygen in the area and suffocation can occur.
5. Sprinkler system pipe. There are several different types of pipe, valves and couplings from schedule 40 to light gage schedule 10 galvanized that are permissible for use in sprinkler systems. All must be NFPA approved.
6. Post indicator valves (PIVs). PIVs are located in the supply line between the city water supply and the sprinkler system riser. The post is located above ground, includes a handle to operate the valve, includes an indicator of the open or shut valve position and includes a padlock for controlled access to operation of the valve.
7. Hose stations. Hose stations in wet pipe sprinkler systems are provided inside of buildings. They include a valve, festooned hose and nozzle and are housed in a cabinet with a glass door.
8. Ionization smoke detectors. Ionization smoke detectors contain a small amount of radioactive material which ionizes air in the sensing chamber, rendering it conductive and permitting a current flow. When smoke particles enter the ionization area the detector circuit responds with an alarm.
9. Photoelectric smoke detectors. Photoelectric spot type detectors contain a chamber that has either overlapping or porous covers of light that allow the entry of smoke. The unit contains a light source and a special photosensitive cell in the darkened chamber. As light is blocked with the admission of smoke particles, light striking the particles is scattered and reflected into the photosensitive cell and a circuit response is initiated.
10. Spot heat detectors. Spot type heat detectors sense heat. Above a predetermined level the detector trips and signals an alarm.
11. Portable fire extinguishers. Portable hand-held fire extinguishers should be provided and located throughout the facility in accordance with the NFPA. Fires that involve typical burning materials such as paper or trash should be treated with a Class A fire extinguisher. Class B extinguishers are used in fires that involve fuels and combustible fluids. Class C should be used in electrical fires. Class D, although rare, should be used on specialized combustible metal such as magnesium. These extinguishers include a variety of fire suppression agents including water fog, CO2, foams and dry chemicals which are matched to the classes of extinguishers available.