Introduction:
All tires in initial stage are small and can be fought easily then and there if trained fire men and well maintained Hand Appliances are available, close to the place of occurrence of tire. Hand Appliances are therefore, of immense importance as they will not let the small lire take to large proportions. F ire multiply to large sizes perhaps because of scheduled areas like warehouses, automatic plants requiring minimal man power, people are available but are not trained for the purpose. Extinguishers and Buckets are not properly maintained they may be empty or not operative at all etc. it is then when comes the role of well laid Fire Hydrant System. Fire hydrant system is capable of extinguishing tires of large sizes in small time if it is handled by trained personnel. As a matter of fact a well designed and well laid F ire Hydrant Service is the back bone of the entire available fire fighting means as it lights fires of serious proportions in all classes of risks and continues to be in full operation even if part(s) of 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 system could be tapped from it, for e.g. spray system foam system etc. The efficiency of fire hydrant services in fighting the fires, however, will depend upon the rapidity with which it is brought into action and ability with its efforts directed The maintenance of fire hydrant system is equally vital and the importance of organized wet drills at regular intervals, which ensure that everyone scares out his allotted duties in the shortest possible time, can be too strongly emphasized.
Hydrants:-
As fire service needs constant supply of water for fighting the fire in a less possible time and constant water supply is needed for pumps, appliances and water tankers to meet this requirement, hydrants are installed on water supply mains with the help of water department. These hydrants are mainly provided in urban areas and industrial compounds, so a fire man should know the types of hydrant it's parts and equipment required for operating the hydrant. A fire authority shall take all reasonable measures for ensuring the provision of water and for securing that it will be available, in case of fire for which fire service is empowered.
Private hydrants.
Private hydrants are often installed in premises with extensive yards, sidings, storage, complex, etc,. Where the nature of the risk require large quantities of water to be immediately at hand. Generally the system provides hydrant outlets at regular intervals and near the strategic risk points maintaining a pressure of atleast 7 bars at the furthest point of the system. These hydrants may be connected to the service main of the premises. Ring mains are also installed without any connection town's main, being supplied from private water supplies, such as overhead, tanks, reservoirs, etc. through pressure pumps. A ring main installation has many obvious advantages, the most important of which is that any hydrant is fed by both arm of the ring and that, since a division valve is fitted is both connections with the town main or other water supplies and sometimes, at intermediate points, it may be possible to isolate a damage section and thus allow a portion of the ring main to remain in action. Where premises are equipped with sprinkler system as well as private hydrants, separate arrangements should be provided for each.
Fixing of hydrant .
Fire hydrants provide the means of drawing water from mains fbr fire fighting. The hydrants are situated in a chamber or pit of brick work or other suitable material which is covered with a removable or hinged lid. ‘
Hydrant and water supplies.
The term hydrant which is believed to be a derivation from the Greek word meaning water is supplied to a special fitting on water supply mains for use by servicespeople, when required for fire-fighting purposes. It allows to connect his hose or stand pipe to the water main and also to control the water as required. It essentially consists of:
(i) A short length of flanged infecting to the water main, or
(ii) A valve or device for turning on and shutting off of water, or
(iii) An outlet terminating in a fire service connection.
Broadly, however, these may be divided into the classes, according to their,position to ground level, wher below the ground level, they are known as:-
(a) Ground and when above the ground level, they are known as Pillar or Post.
(b) Though the former type is more popular in this country there are certainlpurposes for the latter is preferred.
Water distribution system.
Water is obtained by water works authorities from the following main sources:
• River intakes
• lmpounding reservoirs
•Water collected from high ground streams and general rainfall.
•Underground sources such as wells, bores, holes and springs From the above sources, water is gathered into storage reservoirs and is fed into mains after purification.
Water Mains.
They are of three main groups: trunk, secondary and service mains.
Service Reservoirs.
These include over head tanks and water towers. They serve the dual purpose of balancing the distribution system and serve as a reserve water against any possible break down or excessive demands.
Rooster Pumps.
These are used to increase the pressure in mains or in part of the system to overcome frictional loss of where the length of the main is
Types of Hydrant valves:
The principle features of the type of hydrants at present in use in this country are as follows:
Sluice Valve Hydrant: This type of hydrant is not placed above the main, but along side it on a short branch. It consists of three main castings, the inlet piece which is connected to the pipe, the sluice valve itself, and the duck foot bend leading to the out let. This thus hydrant is hydraulically very efficient and when the valve is open, gives a full water way with a negligible loss of pressure.
Screw Down Hydrant: This type of hydrant is being found in most parts of the country. It is attached directly to the main. A mushroom the valve closes on a seating in the base of the hydrant body. The hydraulic attorney of this type various great by with the design of valve and out let bends.
Ball Hydrant: This type of hydrant Was at one time widely used but is now being replaced. It-does net possess a normal type of valve but consists of an out-let against which a hard wooden ball is held in position by the pressure of the water in the main.
Pillar Hydrant: The pillar hydrant combines in permanent form the ground hydrant and the standpipe. It stands 3 feet and 4 feet high, and provide an accessible means of directly connecting hose. It is made of cast irgn, and usually of cylindrical type. The pillar hydrant carries one or two out lets for the connection of hose.
Types of Hydrant systems:
•There are very few pillar hydrants on public highway but these hydrants are found on private premises. Such as factory, godowns and other compounds of the industries.
•The types of pillar hydrant to be found are nearly as numerous as those of ground but they may commonly be found in private promises, such as in factory.
•However, the Indian standard specification (1908-1965) as numerous asamended in 1969 states the following for hydrant of the standard post type.
•The hydrant small consists of one or two sluice valves with a road surface box with a hinged cover, a duck foot bend and a stand post column fitted with 68mm male.
1) Dry Riser
Rising Main, Dry (Dry Riser) A vertical pipe installed in a building for fire fighting purposes, titted with inlet connections at fire brigade access level and landing valves at speciiied point, which is normally dry but is capable of being charged with water usually by pumping from lire service appliances. An arrangement of fire fighting within the building by means of a vertical riser pipe of minimum 100 mm diameter is connected to landing valves located on each floor. The riser pipe normally remains dry. In use of fire, fire brigade vehicle is brought near the building and water is pumped to dry rise: by using the fire 2 ways or 4 way brigade inlets.
Basic requirement of D Riser as per NBC rules.
1.One riser should be considered for a total floor area up to 1000 Sq. M.
2. Riser should be located in lobby approach staircases.
3.Riser size should be 100 mm NB for buildings up to 45 M high and 150 mm NB for buildings between 45 M and 60 M high
4.Fire brigade inlet, with instantaneous male inlet, 2x65 mm (2.5 inch) for each 100 mm NB, 4x65 mm (2.5 inch) for each 150 mm NB riser should be provided.
5.Fire Brigade inlets are fixed on an external wall 1 m above ground.
6.Inlels are enclosed in a wall box with wired glass front marked ‘FIRE BRIGADE
DRY MAIN INLET’.
7.A landing valve with 63 mm instantaneous female outlet should be installed approximately 1 m above floor level on each floor.
8.Whenever possible no part of the floor should be more than 30 m from an outlet.
9.Landing valves must meet the requirements of the local Fire Authority and Fire Brigade.
10. Outlets should be protected from interference by location in recesses and by straps and padlocks.
11. A valve is fitted at the top of each riser to release air during pumping operations.
12. Each dxy riser must be electrically earthed by a direct earth connection.
2.Wet riser
Rising Main, Wet (W et Riser) A vertical pipe installed in a building for fire fighting purposes and permanently charged with water from a pressurized supply, and fitted with landing valves at specitied points. An arrangement of fire fighting within the building by means of vertical riser pipe of minimum 100 mm NB with landing valves on each floor. The riser is normally kept charged with water by a fire pump and a pressurizing pump «galled a jockey pump. The wet riser pipe is also fitted with fire brigade inlet connection at ground level for supply of water from 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.
3) Down Comer [wet pipe] .
An arrangement of fire fighting within the buildings 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 down comer can be treated as a wet riser system described above. The minimum pipe size shall be 100 mm NB connected to hnding valves located on each floor. The down comer pipe is also fitted with fire brigade inlet connection at ground level for supply of Water from 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.
Components/Parts of a hydrant.
The components/part of hydrant for general study may be enlisted as follows:
•Metal pipe connecting the outlet with the main.
•Valve assembly for operating te hydrant on or off.
•Outlet may be threaded or instantaneous
•Blank cap for protecting the outlet.
•Casr iron box, in the case of ground hydrant and casting iron cylindrical follow post in the case of pillar hydrant •Cast iron spindle top
•Frost valve where frost is commonly apprehended.
Hydrant gears and equipments:
The term hydrant gears refers to a number of tools and flttlngs which, a fire fighting appliance has mostly to carry to meet the indispensable or adhoc need that may occur in respect of working from some particular hydrant.
The gears are enlisted hereunder:
•Hydrant box key of hydrant cover key
•Hydrant key (may be double ended or single ended)
•Spindle top adaptors (Eccentric and Square)
•Tommy bar (For ‘Nring the hydrant key)
•Hydrant outlet adaptors
•Hydrant extension piece
•Stand pipe
Operation of hydrant
•Open the hydrant valve slowly.
•Allow some water pass off to ensure that no dirt or flit is left inside that might block or clog the flow at latter stage.
•When closing, close the valve slowly to prevent water-hammer and a possibleburst main;
•After use, see that the hydrant valve is properly closed so that no water leaks out that the pit is left dear and condition in which the frost will not damage it that the frost valve works (where frost valve is present). The valve of a hydrant should not be operated unless standpipe or hose is first connected.
•The stand pipe or hose must not be disconnected from a hydrant in which no water is available or from which the flow had failed until the valve has been shut. This will obviate the danger of the valve being left open with unfortunate consequences when the supply is restored.
•Blank cap on outlet if it is there or box lid if it is a ground hydrant must be restored to position. when the service is over with hydrant.
Hydrant gears and characteristics
Frost Valve: When the valve of a hydrant is closed after use a certain amount of water is trapped in the body of the hydrant between the valve and the out let. This is a source of danger in a cold climate as it may freeze and so prevent the valve being opened -or may crack the hydrant body. Where frost is likely to be experienced, therefore the hydrant should be fitted with means for draining off the water and also to clean after use.
False Spindle:The spindle of a hydrant is usually made of bronze or gunmetal, and in order to protect the top. cap known as false spindle made of harder metal, cast iron or steel is titted over spindle stud.
Direction of Opening: All hydrants should be made to open by turning the spindle antilock wise and should be open very slowly to avoid any damage spindle rod.
Outlets: The link between ground hydrant and the hose is provided by the stand pipe which connects the hydrant and the hose pipe.
Small Gear: Apart from the standpipes, certain small gear for operating hydrants is carried by all the fire fighting appliances such as:
Hydrant Cover Key
Hydrant Key
Hydrant Bar
False Spindle
Hydrant pit cleaning / Hydrant marking from time to time the pit must be cleaned this may be done by hand.
The position of a hydrant should always be clearly indicated. To fix mark or writing front of hydrant.
Direction of use
•Attach the flow tube to stand pipe head;
•Screw on the manometre on to swivel joint at the outlet end of the flow tube adjusting vertical.
•See that the vent plug at the top of the manometre is screwed tightly home.
•If the object is to determine the maximum open delivery discharge of the hydrant, the valve to its full extent;
•If the rate of flow exceeds 7.2 litres : The rate of flow can be read off from the ii range of flow (red figures) engraved on the side of the manometre housing, the water level in the glass tube rises and stabilized.
•If the water does not appear in the glass tube the rate of flow is below 7.2 litres: Open vent plug a few turns to release the residual air, and leave it open, where upon water will rise in the tube and stabilize. Read off the rate of discharge from the low scale of How engraved on the opposite side of observation slot to red figures.
Flow gauging.
•The flow of water per minute as well as the pressure can be ascertained by means of a flow gauge; Compressed air manometres, embodying a precision glass tube polished toan accuracy of one Five thousandth part of an inch in which the velocity head of the water off against a scale calibrated and marked on the face of the slotted tubular housing.
• A scale on the opposite face gives a lower range of flows, brought onto operation by the venting the compression chamber at top of manometre, when the later is as an ordinary open-ended water column. Thus, this one complete instrument reads all Hows from 2.6 to 60 liters owing are the componentsparts:-
•A flow tube fitted inside it with a pitch tube and a swiveling joint near the outlet end
•A manometre fitted with the hexagonal cap on the top
•A compensator plug
•A compensator chamber.
Marking, testing, care and maintenance
A) Attention should be given to the proper marking of hydrant so that they can be found in all conditions or weather or light outlet are to be cleaned at each inspection. Hydrant should be marked, either "Fire drant or FH.”
B) Testing at one of the inspection during the year, each hydrant should be tested in the following "Eanner, using a stand pipe for the purpose:
•The stand pipe should be fitted to the outlet to ensure that the thread or connection is in good order.
•Using a blank cap on the stand pipe with valve in the head which is keptshut, the spindle should be fully worked in the case of a sluice valve hydrant or in the case of full valve hydrant the valve should be operated 11 each case the hydrant should be opened to its full extent and then closed again.
•To ascertain if the hydrant is charged after fully operating the valve, the blank cap should be removed, Or the valve in the stand pipe head opened, and the valve should be partially operated to release small quantity of water through the hydrant.Care should be taken to direct the water in to roadway in order to avoid damage to adjacent property this test should be carried out during the frost weather. Care of frost valve should be taken to see that frost valve(where fitted) is in satisfactory working order. After each inspection or test and when hydrants have been used at fires, hydrants pit should be left empty and clear. Hydrant should be inspected at least twice a year or where circumstances permit four times a year. Attention should be given to pits, frames covers and surface paving round the edges of the frames. A hydrants should not be reported in good working order unless all details in connection with it are complete and in order.
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