2. Why water for fire fighting?
Globally, water is our most plentiful
resource. It is inexpensive.
For these reasons, fire services
throughout the world base their
primary operations upon utilizing
water as a fire
extinguishing agent.
3. Elements used in the system
There are three principle components
to the fire protection element of any
water system;
Storage,
Distribution and
The hydrants themselves.
4. STORAGE
Gravity storage: Water for fire fighting
should be provided by gravity storage
wherever possible.
Storage elevation: 1Ft of head will produce
0.434 p.s.i. of pressure.
Therefore to generate 65 p.s.i. in the water
distribution system, storage reservoirs must
be located at an elevation of approximately
150 ft. above the service area.
(Adequate system pressures is between 65
and 85 p.s.i.)
5. Since most communities are not
perfectly flat, there will be some
variation in service pressure.
In locations where pressure gradients
may fall outside these less desirable
pressure ranges, additional reservoirs
should be set at appropriate elevations
to serve these areas
or
Main-line pressure regulators should
be installed to protect low-lying areas
from over pressurization.
6. DISTRIBUTION SYSTEM
water mains in a grid, with mains and
sub mains interconnecting at roadway
intersections and other regular intervals
helps in feeding fire hydrants from
multiple directions
Hydrants will not be supplied by "dead
end" mains so that discharges will
remain more stable when multiple
hydrants are in use simultaneously.
7. primary feeders which are typically 16 in.
(400 mm) in diameter.
Secondary feeders which are typically 12
in. (300 mm) in diameter would be
appropriate to supply specific
neighborhoods.
8 in. (200 mm) diameter distributor
mains would typically be used to supply
water to individual streets and to the fire
hydrants on those streets. Hydrant
laterals should not be less than 6 in.
(150 mm).
8. HYDRANT DESIGN
Water supply systems in residential areas
should be designed to deliver no less than
1000 GPM (3785 L/min) at each individual
hydrant.
In commercial and multi-story apartment
zones, this volume should increase based
on the required fire flows of the buildings
being protected. If the required fire flows
are several thousand GPM, the required
flow will usually have to be met by two or
more hydrants flowing simultaneously.
9. Hydrants need to be readily
recognizable and accessible.
Shape of the hydrant as well as the
positions of valves and outlets should
be easily recognizable.
Placement of hydrants.
Must be simple and reliable to connect
to and to operate.
Operating nuts should be pentagonal or
triangular in design to reduce tampering
by unauthorized persons.
10. Discharge valves should be specified to
open by turning counter-clockwise and
close clockwise.
Hydrant designs must be appropriate for
the amount of head (static pressure) that
is applied to them. The minimum working
pressure rating of any fire hydrant should
be 150 p.s.i. Hydrants installed in higher
pressure installations should be rated
appropriately.
All fire hydrants should be static tested
at twice the rated working pressure.
11. HYDRANTS
These are devices used for tapping
the water from mains to extinguish
fire.
Also can be used for street washing,
gardening, flushing sewer lines etc.
Provided at the junction of road
where water lines meet
Placed at 100-130m apart along the
road
In case of fire breaks, fire squads
connect hose to hydrant and
extinguish fire
Engine develops required pressure
In case of big cities, water pressure
upto 100m may be required.
Therefore engines, nozzles, etc must
be designed to bare pressure.
12. Generally the following pressure is to
be maintained
7-14m head of water if pumped
through motor
35-49m head if no pump used
• Requirements of a good hydrant
It should be easily connectable to
hose
Cheap in cost and well maintained
Should be easily detachable
Should be reliable
Should allow to draw sufficient
quantity of water
• 2 types of hydrants
Flush hydrants
Post hydrants
13. Flush hydrant:
Installed in an underground brick chamber flush with the foot
path.
Covered from top by CI cover
To locate the position even in darkness some distinct sign is
provided near it at the side of the road with letter FH
• Post hydrants:
The barrel of the hydrant remains projected about 60-90cm
above ground surface
These hydrants have long stem with screw and nut at the top to
regulate the flow of water.
Connected to the main through branch pipe and can be
operated by means of gate valve.
The dia of the hose is 63 mm
Best position is back of curb
