A fire hydrant designed to supply huge amounts of water to fire trucks, very quicky. whenever and wherever fires break out. A typical hydrant has up to four nozzles, one on each side, to which up to four sturdy fire-hoses can be tightly screwed. To prevent tampering, the nozzles are chut by pentagonal (five-sided) nuts that can be opened only with a special wrench. At the top. there is a similar nut and sometimes a wheel directly beneath it. Turning the nut and the wheel unscrews a valve inside the hydrant. This allows water to flow up from an underground pipe and out Denh whichever nozzles have been opened. Unlike an ordinary tap a fire hydrant is designed to anerate either completely on or completely off.
Fire hydrants :
A fire hydrant is an above-ground connection that provides access to a water supply for the purpose of fighting fires. The water supply may be pressure connected to water mains buried in the street or unpressurized, as in the case of hydrants connected to nearby ponds or cisterns. Every hydrant has one or more outlets to which a fire hose may be connected.
If the water supply is pressurized, the hydrant will also have one or more valves to regulate the water flow. In order to provide sufficient water for fire fighting, hydrants are sized to provide a minimum flow rate of about 250 gallons per minute (945 litres per minute), although most as in the case of hydrants hydrants can provide much more.
Fire Hydrant System:
Fire hydrant pump systems (also known as fire pumps, hydrant boosters, fire water pumps) are high pressure water pumps designed to increase the fire fighting capacity of a building by boosting the pressure in the hydrant service when mains is not enough, or when tank fed. Large quantity of water is required for quenching major fires in the industries. Easy accessibility paramount importance in controlling and putting out these fires. Fire Hydrant System is designed to serve these requirements, Components &their Installation.
Fire hydrants operation, appearance, inspection & maintenance:
The user attaches a hose to the fire hydrant, then opens a valve on the hydrant to provide a powerful flow of water, on the order of 350 kappa (50 Ibf/in2) (this pressure varies according to region and depends on various factors including the size and location of the attached water main). This user can attach this hose to a fire engine, which can use a powerful pump to boost threaded connection, instantaneous “quick connector” or a Starz connector.
A user should care not to open or close a fire hydrant too quickly, as this can cause a water hammer, which can damage nearby pipes and equipment. The water inside a charged hose line causes it to very heavy and high water pressure causes it to be stiff and unable to make a tight turn while pressurized. When a fire hydrant is unobstructed, this is not a problem, as there is enough room to adequately position the hose.
Hydrant colouring may be due to either purely practical criteria or more artistic. In the United States, the AWWA and NFPA recommend hydrants be coloured chrome yellow for rapid identification apart from the bonnet and nozzle caps which should be coded according to their available flow. Class AA hydrants (>1500 gpm) should have their nozzle caps and bonnet coloured light blue,
Class A, B, C hydrants:-
Class A hydrants (1000-1499 gpm), green, Class B hydrants (500-999 gpm). orange, Class C hydrants (0-499 gpm), red and inoperable or end-of-system (risking water hammer) black. This aids arriving fire fighters in determining how much water is available and whether to call for additional resources, or find another hydrant. Other coding can be and frequently are used, some of greater complexity, incorporating pressure information, others more simplistic.
In 2011, Code for America developed an “Adopt a Hydrant” website, which enables volunteers to sign up to shovel out fire hydrants after snowstorms. As of 2014, the system has been implemented in Boston, Providence, Rhode Island, Anchorage, Alaska, and Chicago.
Main components of a well-designed hydrant system:
Gravity/ Static Tanks or Sumps:
Tanks of capacity ranging from 110 kilolitre to 225 kilolitre are recommended depending upon the risk to be covered. These should be located between 60 to 200 meters from the risk Proper approach roads of at least 3. 6 meter width should be provided. Arrangement should be made to divide these tanks in two compartments such that one compartment is always available for service while the other can be taken out for cleaning or maintenance purposes.
Two pumps one electric and the other diesel driven (stand by) should be installed to provide water to the installation at a pressure of 7 to 10. 5 kg/cm2 It is preferable to make them start automatically once the. Pressure drops, below the minimum required. Both pumps can be electrically driven provided the source of power supply is from different sources. The capacity of the pump shall be, 2750 litres / minute.
A pump of 500 itters/minute capacity is installed for maintaining pressure in the network A 0′ and when the pressure drops to 6 5 kg fom2 this pump starts automatically, to raise the a oseo u ou Ag Dddo uo pu uoy goo 0 jo amesad juasand o anssajd pressure drops below the set prensure of 3.5 kg/cm” the main pump starts automatically.
It is net pipe work laid underground Where it is not feasible. These can be laid above ground provided the pipes’ are sufficiently supported for its stability. At least one support every10 feet These are laid in ring pattern along the side of the roads /passages.
The hydrants are located betweon2 to 15 meters from the building to be protected in on hazard us are as and 30 meters from the edge of the building accommodating hazardous stores.
Hydrants are installed on 150 mm mains reduced to 100 mm where it is meant to feed single hydrant.
These are the points from where Fire hoses are connected for drawing water. Single outlets fixed with 63 mm diameter in stagnate onset fomale coupling with wheel type control valve called the landing valve coupled to 80 mm diameter stand pipe through a bend. It is erected1 meter above the ground level.
Hydrants are installed from two Independent sources of water 5.25 kg/cm through nozzle of 15-20 mm diameter In this case the stand post diameter is 100 mm provided with a “T” at the top. To each end landing valve is fixed.
These are provided where the hydrants are provided on upper floors of the building. These have one main valve at the ground level. The diameter of such mains is 150mm reduced to 100mm at the top.
Siting & Protection:
- Good sitting and protection of all water supplies is essential.
- These should not be sited with their openings towards explosive store houses etc.
- The fire appliances such as hoses & Branches etc. Should be available close to the hydrants.
- These should not obstruct movement of other emergency services like Fire Engines Ambulances etc.
Inspection and Maintenance;
- These should be inspected, maintained and tested periodically.
- Information regarding the layout of hydrant points, other appliances availability etc.
- Should be available for ready references.
- The names of the contact persons should be displayed.
- Adequate number of persons shall be trained in the’ maintenance and testing of water equipment’s installed.
- Training and Retraining should be carried out to ensure competence of the personnel.
- A viable system for alerting and calling personnel necessary for the efficient operation of all water equipment during silent hours should be incorporated Mock drills should be held at least twice a year.
Public fire hydrants:
Public fire hydrants should comply with the following:
- It should comply with the standard approved by General Directorate of Civil Defence.
- It should be included in piped water distribution system and located along the pavements of streets and public roads.
- Its locations must be determined by the General Directorate of Civil Defence in coordination with Water local Authorities.
- A The local water authorities are responsible for installing, maintaining and repairing public fire hydrants.
- In cities and urban areas a spacing of (90) (120) m is desired between the hydrants.
- The distance between a nearest public hydrant and residential buildings should not exceed 1OOm, and for industrial or commercial buildings should not exceed (60) m.
- A Flow requirements from each hydrant should be (1125) (2000) Lt/min.
- In major fires the flow requirements may range from (5000) to (15000) lt/min from several hydrants.
- In case of installing private hydrants, the water supply, installation and location of the hydrant, should comply with the requirements of three General Directorate of Civil Defence.
Fire-fighting pump set:
- Where a fire fighting pump set is to be installed to provide sufficient flow of water under suitable pressure for fire fighting, the following requirement should be met.
- The pumps used should comply with the standards approved by General Directorate of Civil Defence.
- There should be one duty electric pump and one standby diesel pump and should be capable of maintaining a system pressure of 4. 5 Bar while delivering (1125) Lt/min.
- It should be fitted adjacent to the main water storage tank.
- The power supply equipment must be solely for the use of the fire pumps. Where it is the practice to switch off the supply to the premises it should be ensured that such switching off does not interrupt the mains supply to the fire pumps.
- A separate diesel oil storage tank should be provided, sized to allow (30) minutes running of the diesel pump.
- Pumps room should be constructed from fire resistance non-combustible construction, and used for no purpose other than housing water supplies.
- Adequate ventilation and light should be provided. Floors should be clear form waste at all times.
- In the event of system pressure falling to (2. 7) Bar the electric pump should cut in and boost pressure to (4. 5) Bar.
- The pumps should remain energized until either manually switched off or low water level cut out switch mounted (30} me above tank floor over rides pump.
- In the event of system pressure falling to (3. 0) Bar the diesel pump should cut in and boost pressure to (4. 5) Bar.
- The pump should remain energized until either manually switched off or until fuel runs out.
- The pump set should include a normally closed by-pass valve to allow for testing. The pump set should include a pressure relief valve connected to the by-pass system to open at a pressure of 4. 8 Bar.
- All control panels are to provide the following facilities.
- On/Off/Auto switch for each pump. On light for each pump (Green).
- Trip light for each pump (Red).
- Hour run meter for each pump. System pressure gauge.
- Adjustable pressure settings for high and low pressure setting points.
- Automatic priming devices must be provided, to ensure that the pump will be fully primed.
- The correct sequence of operation of the units shall be ensured and all controls to ensure with water at all times.
Parts of a fire hydrant:
That the system works satisfactorily shall be included. some of the little details you might not have noticed:
- Fire hydrants are just fire hydrants, right? Wrong! Here are Operating nut on top of hydrant turns main water valve on or off.
- Hose is attached to one of the four sides of the hydrant. A clapper valve just inside the hydrant stops water from flowing backwards. Water can flow out of the hydrant into the hose but not in the opposite direction.
- Raised metal body of hydrant ensures it operates at the same height as a fire truck’s water inlet. This helps to stop fire hoses from kinking.
- Breakable bolts on base are designed to snap if a vehicle strikes the hydrant.
- Safety chain stops nozzle caps from getting lost when hydrant is in operation.
- Outlet nozzles have screw threads inside to which fire hoses can be securely attached Remember that the water is at very high pressure and the hoses will come off if they’re not.