Fire Sprinkler system | Firefighting lesson 6
Summary
TLDRThis script offers a comprehensive overview of sprinkler systems, emphasizing the fire triangle's role in fire sustenance. It explains the necessity of heat, fuel, and oxygen for fire and delves into various firefighting systems, particularly sprinkler systems. The video outlines different sprinkler head types, their activation temperatures, and system classifications like wet, dry, pre-action, and deluge. It also covers sprinkler system design considerations, including pipe scheduling, water demand, and layout requirements, ensuring compliance with NFPA standards.
Takeaways
- đ„ The fire triangle consists of three key components: heat, fuel, and oxygen, all of which are necessary for a fire to ignite and sustain.
- đ§ Sprinkler systems are part of automatic firefighting systems, designed to activate and fight fires without human intervention.
- đż Sprinkler heads come in various types, including upright, pendant, sidewall, and concealed, each serving different purposes and spaces.
- đ§ Wet pipe sprinkler systems always contain water, allowing for immediate discharge when activated, whereas dry pipe systems hold water behind a valve until triggered by heat.
- đĄ Pre-action systems and deluge systems are advanced types of sprinkler systems, with the latter being used for high-hazard areas where all sprinkler heads activate simultaneously.
- đïž Firefighting systems in buildings typically include a large water storage tank, a pumping system, and a network of pipes connected to sprinklers or hydrants.
- đ The temperature at which a sprinkler head activates is determined by its rating, identified by the color of the liquid in the bulb (for glass bulb sprinklers).
- đ The design and layout of sprinkler systems depend on factors like hazard classification, with specific spacing requirements for sprinkler heads according to NFPA 13 standards.
- đŠ The minimum water supply for pipe schedule systems is determined based on factors such as water flow rate, residual pressure, and system duration, ensuring adequate firefighting capability.
- đ§ Floor control riser assemblies in buildings may include various components like auxiliary drain valves, pressure-reducing valves, and water flow switches, all critical for efficient and safe system operation.
Q & A
What is the fire triangle and why is it important?
-The fire triangle is a scientific principle representing the three components needed to ignite and sustain a fire: heat, fuel, and oxygen. It is important for understanding how fires sustain themselves and is essential background information for using fire safety equipment.
What is a flash point in the context of fire safety?
-A flash point is the lowest temperature at which a material can ignite. Different materials have different flash points, and understanding them is crucial for fire prevention and safety.
How does a fire blanket work in relation to the fire triangle?
-A fire blanket works by removing the oxygen side of the fire triangle. It either removes or displaces oxygen, causing the fire to suffocate and thereby ceasing the combustion reaction.
What are the two types of firefighting systems mentioned in the script?
-The two types of firefighting systems mentioned are manual and automatic. Manual systems require physical intervention, while automatic systems fight fires without human intervention.
What are the three basic parts of a sprinkler system?
-The three basic parts of a sprinkler system are a large store of water in fire storage tanks, a specialized pumping system, and a network of pipes ending in either hydrants or sprinklers.
What are the four most common styles of sprinkler heads?
-The four most common styles of sprinkler heads are the standard spray upright, standard spray pendant, sidewall sprinkler, and concealed sprinkler head.
What is the purpose of the heat-sensitive element in a sprinkler head?
-The heat-sensitive element in a sprinkler head allows water to flow at a given temperature, activating the sprinkler when the temperature reaches a certain threshold.
What are the four main types of fire sprinkler systems?
-The four main types of fire sprinkler systems are wet pipe, dry pipe, pre-action, and deluge systems.
How does a dry pipe system differ from a wet pipe system?
-A dry pipe system is not constantly filled with water; instead, water is held behind a dry pipe valve. When a sprinkler head activates due to heat, air is released, causing a pressure drop that opens the valve and allows water to fill the system.
What is unique about the operation of a pre-action system?
-A pre-action system does not admit water into the system's piping until a pre-action valve is opened, which is triggered by one or two events: sprinkler activation and detection device activation, depending on the type of pre-action system installed.
What is the purpose of a deluge system in fire protection?
-A deluge system uses open sprinklers or nozzles and is activated by a detection system such as smoke detection. Once activated, water fills the system and flows from every open sprinkler head, providing immediate and extensive water coverage.
Outlines
đ„ Fire Triangle and Firefighting Systems Overview
This paragraph introduces the concept of the fire triangle, which is a fundamental principle in firefighting, emphasizing the three essential components for fire ignition and sustenance: heat, fuel, and oxygen. It explains the role of flash points in ignition and discusses common fuel sources found in homes and businesses. The paragraph also covers the function of fire blankets and extinguishers in disrupting the fire triangle. It then transitions into an overview of firefighting systems, distinguishing between manual and automatic systems, with a focus on sprinkler systems. The components of a sprinkler system are outlined, including fire storage tanks, pumping systems, and pipe networks. The paragraph concludes with a mention of various sprinkler head types and their components, highlighting their temperature ratings and activation mechanisms.
đ§ Sprinkler Head Types and Fire Sprinkler System Designs
This paragraph delves into the different types of sprinkler heads, including upright, pendant, sidewall, and concealed, detailing their specific functions and ideal applications. It further explains the four main types of fire sprinkler systems: wet pipe, dry pipe, pre-action, and deluge systems. Each system's unique components and operational mechanisms are described, such as the presence of water in the pipes for wet systems and the delayed water flow in dry pipe systems. The paragraph also touches on the pre-action system's reliance on detection device activation and the open sprinklers used in deluge systems. Lastly, it discusses the considerations for selecting an appropriate sprinkler system based on the level of hazard and the design layouts for fire sprinkler systems, including tree, grid, and looped systems.
đą Fire Sprinkler System Layout and Water Supply Requirements
The final paragraph focuses on the design and layout of fire sprinkler systems, particularly tree systems, and the calculations for water demand. It provides an example of designing a tree sprinkler system for a light hazard office area, explaining the maximum coverage area per sprinkler head, design spacing, and distance from walls. The paragraph outlines the methods for determining water supply requirements, such as the pipe schedule method and hydraulic calculation method. It also details the minimum water flow rate, residual pressure, and duration for pipe schedule systems, emphasizing the need for a sufficient water tank. The paragraph concludes with a discussion on the components and considerations for a floor control riser assembly, including pressure reducing valves, control valves, and water flow switches, as well as their specifications and requirements.
Mindmap
Keywords
đĄFire Triangle
đĄFlash Point
đĄFirefighting Systems
đĄSprinkler System
đĄStandard Spray Upright
đĄPendant Fire Sprinkler Head
đĄSidewall Sprinkler Heads
đĄConcealed Sprinkler Head
đĄWet Pipe System
đĄDry Pipe System
đĄPre-Action System
đĄDeluge System
Highlights
The fire triangle is a fundamental principle that explains how fires sustain themselves, consisting of three elements: heat, fuel, and oxygen.
Heat is required for ignition, with different materials having specific flash pointsâthe lowest temperature at which they ignite.
Fuel sources in homes and businesses include paper, oil, wood, and fabrics, all of which can sustain a fire.
Oxygen, which makes up 21% of Earth's atmosphere, is essential for sustaining the combustion reaction.
Firefighting systems are classified into manual and automatic systems, with sprinkler systems being an example of automatic systems.
Sprinkler systems consist of three basic parts: fire storage tanks, a specialized pumping system, and a large network of pipes ending in either hydrants or sprinklers.
The four most common types of sprinkler heads are: upright, pendant, sidewall, and concealed.
Sprinkler systems are categorized into four main types: wet pipe, dry pipe, pre-action, and deluge systems.
Wet pipe sprinkler systems always contain water in the pipes, which is immediately discharged through the sprinkler heads when activated.
Dry pipe systems hold water behind a dry pipe valve and release it only when the sprinkler head is activated, making them suitable for unconditioned spaces.
Pre-action systems are similar to dry pipe systems, but water is admitted into the system only after specific detection events occur.
Deluge systems use open sprinklers or nozzles, allowing water to flow from all heads once the detection system is activated.
The layout of fire sprinkler systems can follow different designs, including tree, grid, and looped configurations.
The maximum area of coverage per sprinkler head depends on the hazard classification and mounting orientation, based on NFPA 13 standards.
Water demand for firefighting sprinkler systems is determined by either the pipe schedule method or the hydraulic calculation method, ensuring proper coverage and pressure.
Transcripts
[Music]
sprinkler systems
before diving in the sprinkler system
let us go through some basic information
related to firefighting
the fire triangle
the fire triangle is a scientific
principle that is important for all
people to be aware of understanding how
fires sustain themselves is essential
background information in situations
where you may have to use fire safety
equipment
the fire triangle or combustion triangle
is the three components needed to ignite
and sustain a fire
the three ingredients of a fire triangle
are
heat fuel and oxygen
first a source of heat is required for
ignition to occur and different
materials have different flash points
flash point is the lowest temperature at
which the material ignites
second a fire cannot begin if there is
no material to burn
homes and businesses are full of
flammable materials such as paper oil
wood and fabrics any of these can serve
as a fuel for a fire
third to sustain the combustion reaction
oxygen is needed as it reacts with the
burning fuel to release heat and co2
earth's atmosphere consists of 21 oxygen
so there is plenty available to trigger
a fire if the other two components are
present fire blankets and certain fire
extinguishers remove the oxygen side of
the triangle by removing it or
displacing it causing suffocation and
thereby ceasing the combustion reaction
so here are some facts about the fire
triangle that we should keep in mind
normal air contains 21 percent oxygen
fuel may also contain oxygen heat
sources include the sun hot surfaces
sparks friction and electrical energy
fuel sources can be a solid liquid or
gas
firefighting systems are classified
either manual or automatic
manual firefighting systems includes
extinguishers fire cabinets siamese
connection and fire hydrants
these requires the physical intervention
of manpower to fight the fire automatic
system as its name says fights the fire
automatically without the intervention
of human being and that what a sprinkler
system do
here is a schematic diagram of the
system components
usually both systems exist in all
buildings to form a competent
firefighting system matching the nfpa
standards
so in any building the system consists
of three basic parts a large store of
water in tanks either underground or on
top of the building called fire storage
tanks
a specialized pumping system this
usually includes three types of pumps
jockey pump electric pump and diesel
pump
you can refer to my video about fire
pumping system for more info
a large network of pipes ending in
either hydrants or sprinklers nearly all
buildings require both of these systems
sprinkler systems when it comes to the
sprinkler head itself the four most
common styles of sprinklers are
the standard spray upright standard
spray pendant
sidewall sprinkler concealed sprinkler
head
nearly all fire sprinklers are composed
of the same components
a ceiling assembly or plug that prevents
water from escaping a heat sensitive
element that allows water to flow at a
given temperature a deflector that
distributes water effectively in a frame
the sprinkler's temperature rating is
the temperature at which the sprinkler
will activate
options range from 135 to 650 degrees
fahrenheit
these ratings can be identified by the
color of the liquid inside the bulb in
the case of glass bulb sprinklers
the selection is taken from nfpa 13
table 7241 based on the hazard class for
the structure that the fire sprinkler
system is protecting
upright sprinkler head upright fire
sprinklers spray water upward to a
concave deflector like an umbrella
producing a dome-shaped spray pattern
rather than descending through the
ceiling these sprinkler heads are
usually mounted on pipes just below the
ceiling upright sprinkler heads are
efficient at dispersing water between
obstructions thus they are frequently
used for rooms that are inaccessible
such as mechanical rooms and in
warehouses and industrial spaces they
are also often applied in structures
with open ceilings
the pendant fire sprinkler head it is
the most common type that you will see
pendant sprinkler heads descend from the
ceiling with a convex circular gap
deflector plate on the bottom
when the sprinkler heads activate they
send a stream of water downward onto
their deflectors which then disperse the
water widely side to side throughout the
room in a conical pattern
sidewall sprinkler heads
protrude horizontally out of the wall
parallel to the floor rather than
descending from the ceiling or mounted
on a pipe pointing upward
sidewall sprinklers are ideal for small
spaces such as hallways spaces with
obstructions and where ceiling piping is
not available
concealed sprinkler head
this heat sensitive plate detaches at
temperatures roughly 20 degrees lower
than the fire sprinkler head allowing
the concealed sprinklers deflector to
drop in the head to activate
now we have covered the most common
sprinkler head types let's go ahead and
discover the fire sprinkler system types
there are four main types of systems
what pipe system
dry pipe system
pre-action system
and deluge system
wood pipe sprinkler systems here are the
components of a wet sprinkler system
in addition to the water supply piping
and sprinklers these systems have
backflow prevention device
control valve
main drain
fire department connection
water flow alarm
wet pipe sprinkler systems always
contain water in the riser and piping
as soon as a sprinkler head activates
due to the heat of a fire water is
immediately discharged through the open
head
dry pipe fire sprinkler systems
dry pipe systems are very similar to
what pipe systems with one major
difference
the pipe is not constantly filled with
water instead the water is held behind a
dry pipe valve usually some distance
away from where the sprinklers are
located
like a wet pipe system when the
temperature at the ceiling becomes hot
enough the glass bulb or fusible link of
the sprinkler breaks however in this
case water isn't immediately available
because the pipe is not water filled
instead air is released from the now
open sprinkler head
this creates a drop in pressure causing
the dry pipe valve to open in water to
fill the system
water will then flow from the open
sprinkler head
since there is a delay between sprinkler
operation and water flow the size of dry
pipe systems is limited
the size limitation is intended to
minimize the amount of time water
delivery is delayed
a dry pipe system is a great option for
unconditioned spaces or locations where
the temperature of the space cannot be
guaranteed to be high enough to prevent
water in the system from freezing
pre-action system
a pre-action type sprinkler system
employs the basic concept of a dry pipe
system and that the sprinklers are
closed in water is not normally
contained within the pipes
one difference however is how water is
admitted to the system
water introduction into the system's
piping is initiated by opening of a
normally closed mechanically latched
valve known as a pre-action valve
means of operating the pre-action valve
depends on which of the three types of
pre-action systems non-interlock single
interlock or double interlock is
installed
pre-action valve operation is dependent
upon one or two of the following events
occurring sprinkler activation and
detection device activation
a non-interlock system requires only one
of either event to occur before water is
admitted into the system
a single interlock system is activated
only upon the event of detection device
activation
however in a double interlock system the
two separate events must happen before
water is admitted into the system
sprinkler activation and detection
device activation
deluge systems
are similar to pre-action systems in
that they use another type of detection
for operation however the biggest
difference is that deluge systems use
open sprinklers or nozzles
instead of getting water flow from
individual heads that have operated once
water fills the system water will flow
from every sprinkler head
much like a pre-action system a deluge
valve will keep water from filling the
system until the operation of another
type of detection system such as smoke
detection
once the detection system is activated
water not only fills the system but
flows from the open sprinklers or
nozzles
an important consideration in the
selection of the type of sprinkler
system is the level of hazard being
protected if protecting an area of very
high hazard such as aircraft hangers a
deluge system may be the most suitable
automatic sprinkler system design
the layout of fire sprinkler systems is
usually one of the following
tree sprinkler system it is the normal
design system and it consists of main
pipeline with branches on both left side
and right side
grid sprinkler system a sprinkler system
in which parallel cross mains are
connected by multiple branch lines
looped sprinkler system a sprinkler
system in which multiple cross mains are
tied together so as to provide two paths
for water to flow to an operating
sprinkler and branch lines are not tied
together
the maximum area of coverage per
sprinkler head depends on hazard
classification and sprinkler mounting
orientation that is sidewall or overhead
sprinkler head spacing the table below
shows sprinkler spacing requirements
based on nfpa 13 for example in a light
hazard office area the maximum coverage
area per sprinkler head is 200 square
feet and the maximum design spacing
between sprinklers is 15 feet the
maximum distance of sprinkler head from
wall is half of the maximum distance
between sprinkler heads minimum distance
between sprinklers is typically six feet
let us take an example an office area of
ninety by sixty feet
assume we want to design a tree
sprinkler system let us go ahead and lay
out the piping system and sprinkler
heads being a light hazard the maximum
spacing between sprinklers is 15 feet
the distance between sprinklers and
walls is no more than half than the
distance between sprinklers
the water demand for firefighting
sprinkler systems shall be determined by
either the pipe schedule method or the
hydraulic calculation method
according to nfpa 13 pipe schedule
system is defined as sprinkler system in
which the pipe sizing is selected from a
schedule that is determined by the
occupancy classification and in which a
given number of sprinklers are allowed
to be supplied from specific sizes of
pipe since our space is considered light
hazard and having no more than two
sprinkler heads on each branch then the
size of all branches is one inch
for the main line always start from the
end this portion is feeding four
sprinkler heads then its size should be
one and half inches
this portion is feeding eight sprinkler
heads then its size should be two inches
and all the rest are two and a half
inches because the number of sprinkler
heads is more than ten and less than
thirty
what is the minimum water supply
requirements for pipe schedule systems
the table below summarizes the minimum
water flow rate residual pressure and
duration of pipe schedule systems
therefore 500 gpm multiplied by 30
minutes means a minimum of fifteen
thousand gallons water tank shall be
constructed
a breakout of a floor control riser
assembly the following is a full
arrangement for a combination standpipe
sprinkler riser where high pressures
necessitate a pressure reducing valve at
each level while every element in this
specific arrangement is certainly not a
necessity on every project here's some
considerations that go into the
requirements and considerations for a
layout like this auxiliary drain valve
permits faster draining of system as
opposed to only draining inspectors test
valve
check valve can help reduce false water
flow alarms on floor where sprinklers
have not activated drain pipe size three
quarter inch for two inch system pipe
one and quarter inch for two and half to
three in half system pipe or two inch
for four inch system pipe drain valve
minimum size three quarter inch for five
to fifty gallon system one inch for
above 50 gallon system drain riser
discharge must be to outside or drain
capable of handling the flow size must
be at least one pipe size larger than
the largest drain connection tying into
it
inspectors test must be accessible and
must discharge outside or to a drain
capable of handling flow must be
downstream of water flow alarm pressure
gauge required at each floor control
valve pressure reducing valve provided
to reduce the system pressure such that
the working pressure will not exceed a
standard 175 psi listed pressure of the
sprinklers piping and fittings prvs can
also be used to limit the system
pressure to higher amounts when
pressures are allowed to exceed 175 psi
control valve for entire riser is
required to permit isolating a riser
without interrupting other systems
size of minimum 4 inch unless
hydraulically calculated to permit
smaller size
sight glass enables easy verification of
water flow for inspectors test floor
control valve
must be accessible electrically
supervised or locked signage must be
provided and shall be tested annually
water flow switch is used in wet
sprinkler systems to detect the flow of
water and to send an alarm signal
[Music]
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