A well designed and a well laid out Hydrant System forms the backbone of the entire fire fighting system. Hydrant Fire Protection System is designed to fight fire of huge proportions, in all classes of risks. It is designed to be in operation even if a part of the affected structure collapses
The fire hydrant system like the portable fire Extinguishers basically uses water as extinguisher. In certain types of fires, special branch pipes are used to deliver a type Foam in conjunction. A raging fire without a proper extinguishing system can be devastating. Hence there is an emphasis on provision of a fire hydrant system. In the fire hydrant system the water in large quantum is pumped continuously with tremendous force and velocity so as to reach the seat of fire. Hydrant valves are located at strategic points. These work as outlets of water through the fire Hose.
Sprinkler System provides the best form of protection, as it is designed to both detect and extinguish fire. The important aspect of this system is that it directly attacks the seat of the fire, avoiding unnecessary floor wettings. With this system chance of fire spreading to other areas is also eliminated.
For fire protection purposes, an integrated system of underground and overhead piping designed in accordance with fire protection engineering standards. The installation includes one or more automatic water supplies. The portion of the sprinkler system aboveground is a network of specially sized or hydraulically designed piping in a building, structure, or area generally overhead and to which sprinklers are attached in a systematic pattern. The valve controlling each system riser is located in the system riser or its supply piping. Each sprinkler system riser includes a device for actuating an alarm when the system is in operation. The system is usually activated by heat from fire and discharges water over the fire area.
Medium Velocity Water Spray System is used for the following:
Fires involving liquids with flash points below 32 0C cannot always be extinguished by water spray. Medium Velocity Water Sprayers giving medium drop size can be successfully employed for flame control in many cases. It is important to use the correct water density rate and drop size, to avoid undue agitation of the burning liquid. Flame height can be controlled within tolerable limits, and personnel can enter the area to drain off the liquid and carry out any other measures necessary to bring the situation under control.
Gases liberated from these highly volatile liquids from explosive mixtures with air. They are mostly heavier than air, and dissipation may be very slow. Ignition can take place at considerable distances from a source of leakage, and extensive fires result. Medium Velocity Water Sprayers are positioned to cover valves and joints where leakage may occur, and enable the gas to be burnt safely until the leakage is sealed off.
Hazards of this kind are always present where Liquefied Petroleum Gases (commonly termed as LPG) are being stored, transported, or used in manufacturing processes.
SCOPE OF APPLICATIONS
Applications of the MVWS system may be broadly classified as follows.
Fires involving flammable liquids and certain solids and semi solids, (with flash points between 32 0C and 65 0C) For such hazards Medium Velocity Water spray provides effective control by cooling, and by extinguishing principles other than emulsification. The fire is prevented from spreading to adjacent plant and building and may under favorable conditions, be completely extinguished.
Few examples are
Fires involving flammable liquids liquefied gases and certain solids and semi-solids, which cannot be extinguished by any form of water spray, or where it is not desirable to extinguish the fire completely. The objects of this application are to control the rate of bringing, prevent dangerous increase of pressure in vessels exposed to fire, and protect adjacent plot and buildings. These liquids have flash points below 32 0C.
Risk in which the main hazard is the exposure of plant and buildings to heat from a fire in their vicinity. the objects in this case is cooling to prevent increase of pressure in vessels to minimize fire damage and prevent the spread of fire. This application includes all exposure risks.
The High velocity Water Spray System has been developed for the extinguishments of oil fines, and it introduces an entirely new principle in fire extinguishments. It is employed to bring about a fundamental change in the nature of the inflammable liquid, which is converted temporarily into an emulsion which cannot burn.
A special type of nozzle, termed a projector, is employed, discharging a cone of water in the form of evenly distributed broken streams of high velocity and high momentum. The rapid movement of the broken streams of water is suddenly arrested at the oil surface and the impact causes the oil to be broken up into tiny globules to form an emulsion with the water. In this manner, almost immediately the water from the projector strikes the burning oil-in-water emulsion is formed which cannot burn.
In addition, the dispersion of the oil in minute globules in the water gives almost instantaneous cooling and thus, together with the extinguishments of the fire, there is simultaneous cessation of the formation of oil vapour.
When an emulsion formed by the "High Velocity Water Spray" system is allowed to rest for a considerable period of time, the oil and water will separate. Such an emulsion is said to be unstable. It must be realized, however, that most emulsions formed by the "High Velocity Water Spray" system, although not stable (or permanent), remain emulsions for a sufficient length of time to prevent recurrence of ignition after the water discharge has ceased.
With the "High Velocity Water Spray" System, fires of all light mineral spirits such as petrol, paraffin, benzene and white spirit can be extinguished, but whereas the emulsions formed with the heavier oils persist for sometime, those formed with the light spirits are transient.
For this reason, complete extinguishments of the light mineral spirit cannot be assured unless the whole of the burning surface is brought under simultaneous bombardment from the projectors. It will be appreciated that such a state of affairs is not always possible, for even with the ideal design of protection the fire may be preceded by an explosion causing disarrangement of the plant and some shielding of the burning liquids. On this account the "High Velocity Water Spray" system can only be put forward in such cases after a full enquiry into all the circumstances.
Foam fire suppression systems are used primarily to protect hazards or areas with flammable liquid fire hazards. The fire extinguishing foam is made from missing foam concentrate and water within the piping network. The foam extinguishes fire by smothering the fire, suppressing flammable vapor production, and cooling the fuel in adjacent areas.
The specifications for piping material that carries foam concentrate and solution must be closely coordinated with the recommendations of the foam manufacturer. Often stainless-steel piping is recommended. Selecting an inappropriate piping material may increase maintenance needs on the system and decrease the piping usable service life.