Fire hydrant And Different types

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  • All fire in the initial stage is small and can be fought easily then and there if trained firemen and well-maintained Hand appliances are available, close to the place of occurrence of fire. Hand Appliances are, therefore, of immense importance as they will not let the small fire take too large proportions. Fire multiply to large sizes perhaps because of scheduled areas like warehouses, automatic plants requiring minimal manpower, people are available but are not trained for the purpose. Extinguisher and buckets are not properly maintained- they may be empty or not operative at all etc. it is then when comes the role of a well-laid fire hydrant system.

Fire hydrant And Different types

  • Fire hydrant systems are capable of extinguishing fires of large sizes in small time if it is handled by trained personnel. As a matter of fact, a well designed and well-laid fire hydrant service is the backbone of the entire available fire fighting means as it fights fires of serious proportions in all classes of risk and continues to be in full operation even if part of the affected building and/or structures have collapsed, and also keeps cool all adjoining properties, thereby minimizing the exposure hazard.it is a mother system. all water systems could be tapped from it, for e.g. spray system from system, etc-Fire hydrant And Different types

Basic Hydrant Network :

  • All occupancies are not alike as far as the fire hazard is concerned and as such in order to optimize the design, these have been divided into four categories viz. Light, ordinary, high hazard class A and high hazards class B.
  • Therefore,  designing a fire hydrant service for a particular risk, a decision should be made as to which class of hazard the risk belongs to and accordingly the system be designed following the rules applicable to that class of hazard. however, a compromise may be made when designing the system for high hazard class brisk like fertilizer plant, refineries, etc. where areas of the risk belonging to the ordinary class of hazard like utilities, services, godown, etc. may be provided hydrant posts spaced as per the rules applicable to the ordinary class of risks.

Fire hydrant And Different types

  • Fire hydrant systems should be designed in rings so as to receive water at a place via two routes. For convenience & simplicity of design, pre-calculated sizes & pipe percentages have been given in TAC F.P.Manul.The system could be designed into single or more than one interconnected systems. However, every system shall comply with pumping & water requirements independently. 
  • The choice is given to design a system hydraulically [for hydrant posts exceeding 55 nos.] with a minimum pressure of 3.25kg/cm2 at any point in the system. All high hazard occupancies shall be designed hydraulically with a minimum pressure of 5.25 kg/cm2 at any point in the system. It should be noted that the lowest size of pipe in any hydrant system should not be below 100mm dia. The storage vessel/tanks containing the liquids with a flashpoint less than 32-degree c besides hydrant service are necessary to be protected by either medium velocity spray system and /or fixed foal system. water for the same may be tapped from the hydrant network-Fire hydrant And Different types 

The hydrant systems are of following different types :

  • 1) Dry-riser
  • 2) Down comer
  • 3) Wet riser

[1] Dry-riser :

  • Rising main, Dry (Dry River)- A vertical pipe installed in a building for fire fighting purpose, fitted with inlet connections at fire brigade access level and landing valves at a specified point, which is normally dry but is capable of being charged with water usually by pumping from fire service appliances. an arrangement of fire fighting within the building by means of a vertical riser pipe of a minimum 100 mm diameter is connected to the landing valves located on each floor. The riser pipe normally remains dry. in case of fire, the fire brigade vehicle is brought near the building, and water is pumped to the dry riser by using the fire 2 ways or 4-way brigade inlets.

[2] Down comer (wet pipe) :

  • An arrangement of fire fighting within the building by means of a pipe connected to the discharge of a fire pump with a suction tank located on the terrace. The pump discharge is fitted with a non-return valve & gate valve. hence the downcomer can be treated as a wet riser system described above. The minimum pipe size shall be 100 mm NB connected to landing valves located on each floor. the downcomer pipe is also fitted with the fire brigade inlet connection at ground level for the supply of water from a fire service appliances using a 2 way or a 4-way fire brigade inlet with a non-return valve. an air release valve is provided on the topmost point of the riser. inlet above the terrace level.

[3] Wet riser :

  • Rising main, Wet (wet riser) – A vertical pipe installed in a building for fire fighting purpose and permanently charged with water from a pressurized supply, and fitted with landing valves at specified points. An arrangement of fire fighting within the building by means of a vertical riser pipe of a minimum 100 mm with landing valves on each floor. the riser is normally kept charged with water by a fire pump and a pressurizing pump called a jockey pump. the wet riser pipe is also fitted with the fire brigade inlet connection at ground level for the supply of water from the fire service appliances using a 2 way or a 4-way fire brigade inlet with a non-return valve. An air release valve is provided on the topmost point of the riser read more…

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