Ch.16 Fire Suppression Systems - State Final Review
One of 3 mechanisms to activate FTHD
1 expansion of heated material (fusible link, bimetallic) 2 melting of heated material (frangible bulb) 3 changes in resistance of heated material (continuous line)
Fixed temp. heat detectors
1 relatively inexpensive 2 least prone to false activations 3 can be slowest to activate
Where would a deluge system most likely be found
Aircraft hangar
System of water pipes, discharge nozzles, and control valves designed to activate during fires by discharging enough water to control a fire is formally known as
Automatic sprinkler system
What is the most reliable fixed fire suppression system
Automatic sprinklers
Fire pumps and foam extinguishing systems that sense heat, smoke, or gas and activate automatically
Automatic suppression systems
Where are control valves usually located
Between the source of water supply and the sprinkler system
Sprinkler system that protects an entire building
Complete sprinkler system
System similar to dry pipe systems in that there is no water in distribution piping before system activation but different in that it has no fusible links
Deluge system
Fire suppression system that consists of closed sprinklers attached to a piping system that contains air under pressure
Dry pipe system
Point at which fire department can connect into a sprinkler or standpipe system to boost waterflow in the system is known as
Fire Department Connection (FDC)
What gases are always released from fire?
H2O (water vapor), CO2, CO - others depend on fuel involved
How are sprinkler systems normally operated
Hydraulically
Changing Sprinklers
In may jurisdictions the job of changing sprinklers must be performed by the reps of the buildings occupants who are qualified to perform work on sprinkler systems. In others firefighters are allowed to replace fused or damaged sprinklers. Follow SOPs.
Frangible bulb
Incorporates a small bulb filled with liquid and an air bubble to hold the orifice shut. Bubble prevents false activations through changes in atmospheric conditions. In a fire heat expands the liquid until the bubble is absorbed into the liquid. this increases the internal pressure until the bulb shatters at the proper temperature. Regulated by the amount of liquid and the size of the bubble in the bulb.
Auxiliary system w/in occupancy that is attached directly to hard wired or radio type municipal fire alarm master box
Local energy system
Water supply
Minimum water supply has to delive the required volume of water to the highest sprinkler at a residual pressure of 15psi. Depends on the hazard, occupancy, and the building contents. In most cases the water supply for the sprinkler system is designed to supply only a fraction of the sprinklers actually installed on the system. Additional water and pressure must be supplied
Standard on Carbon Dioxide Extinguishing Sytems
NFPA 12
NFPA standard for installing sprinkler systems in one and two family dwellings
NFPA 13D
Waterflow Alarms
Normally operated either hydraulically or electrically. hydraulic is a local alarm that is used to alert the personnel in the building or a passerby. Electric may also be employed to alert building occupants and can be configured to notify the FD
What is an indicating control valve
One that shows at a glance whether it is opened or closed
What alarms are more reliable?
Ones powered by household current
Type of control valve in which the position of the center screw indicates whether the system is open or closed
Outside stem and yoke valve
Reason that a sprinkler system may not perform
Painted over sprinklers
System that doesn't interconnect with municipal alarm circuit
Parallel telephone system
Sprinkler system that protects high-hazard areas only
Partial sprinkler system
Most common sprinkler in use extends down from piping
Pendant
Type of valve used to control underground water mains and provides a visual means for indicating "open" or "shut"
Post indicator valve
Uses circular disk inside a flat plate on top of the valve housing to show whether the valve is open or shut
Post indicator valve assembly
System used when it is especially important to prevent water damage even if the pipes are broken
Preaction system
Dry systems that employ a deluge type valve, fire detection devices, and closed sprinklers are
Preaction systems
System used to protect large commercial and industrial buildings, high rises, college campuses
Proprietary systems
Detector designed for use in areas of normally subject to regular temp. changes that are slower than those under fire conditions
Rate compensated detector
System that connects to fire dept. telecom center directly or thru answering service by means other than municipal fire alarm box system
Remote station system
Type of system covered by NFPA 13D and may be wet or dry pipe
Residential system
Chamber that catches excess water that may be sent through the alarm valve during momentary water pressure surges
Retard chamber
Upright
Screwed into the top of the piping and discharges water into a solid deflector, that breaks it into a hemispherical spray pattern that is redirected to the floor. Cannot be changed into the pendant position.
System in which municipal alarm circuit extends into protected property
Shunt system
Sprinkler used in corrosive atmospheres
Special-purpose
Sprinklers in the automatic sprinkler system are sometimes known as
Sprinkler heads
NFPA 13
Standard for the installation of sprinkler systems
NFPA 13D
Standard for the installation of sprinkler systems in one and two family dwellings and manufactured homes
NFPA 13R
Standard for the installation of sprinkler systems in residential occupancies up to and including four stories in height.
Newer wet pipe systems with a backflow prevention check valve and electronic flow alarm are referred to as
Straight stick systems
Rate of rise detector that operates on principle that when 2 wires of dissimilar metals are twisted together and heated at one end, an electrical current is generated at other end
Thermoelectric detector
Pendant
This is the most common type in existence today, extends down from the underside of the piping.
Primary purpose of the main drain
To allow service personnel to drain water from the system for maintenance purposes
Purpose of inspector's test valve
To simulate action of one sprinkler
Common capabilities of proprietary systems
Transmitting coded alarm and trouble signals Monitoring building utility controls Monitoring elevator status Monitoring fire and smoke dampers Performing security functions
Screwed into top of piping and has hemispherical spray pattern that is redirected towards floor
Upright
Wet Pipe System
Used in locations where the temps are not expected to go below 40F. Simplest type of fire sprinkler system and generally requires little maintenance. Water is under pressure at all times. This type of system is equipped usually with an alarm check valve. Newer ones may not, instead having a backflow prevention check valve and an electronic flow alarm
Valve that extends horizontally through the wall with the target and valve operating nut on the outside of the building
Wall post indicator valve
Gases released by fire
Water vapor (H2O) Carbon dioxide (CO2) Carbon monoxide (CO) Hydrogen chloride (HCl) Hydrogen cyanide (HCN) Hydrogen fluoride (HF) Hydrogen sulfide (H2S)
Simplest sprinkler system and one that requires little maintenance
Wet pipe system
Chemical Pellet
a pellet of solder under compression within a small cylinder melts at a predetermined temperature allowing a plunger to move down and release the valve cap parts
Nationally recognized labs
all parts and components of the sprinkler system should be listed by a nationally recognized testing lab such as Underwriters Labs Inc or FM Global.
Preaction Systems
are dry systems that employ a deluge type valve, fire detection devices and closed sprinklers. This type of system is used when it is especially important to prevent water damage even if the pipes are broken.
Deluge Systems
are similar to dry pipe systems in that there is no waterr in the distribution piping before system activation. they differ from in that the sprinklers have no fusible link and do not function as fire detection devices. All the sprinklers are open all the time. Normally installed in high hazard area.
Control Valves
are used to turn off the water supply to the system in order to replace sprinklers, perform maintenance or interrupt operations. They are located between the source of the water supply and the sprinkler system, usually under the sprinkler alarm valve.
Sprinklers are effective in
protecting occupants in other parts of a building
partial sprinkler system
protects only certain areas or places designated by code
Complete Sprinkler system
protects the entire structure
Sprinkler FDC
should be supplied with water from pumpers that havee a capacity of at least 1,000gpm with a minimum of two 2.5" or larger hoses.
WPIV
similar to the PIV except that it extends horizontally through the wall with the target valve operating nut on the outside of the building.
Quick Opening Device
since several minutes could be lost while the air is being expelled from thhe system. standards require that a quick opening device bee installed in systems that have a water capacity over 500 gallons. An accelerator is one type of quick opening device.
Following Fire
the sprinkler equipment should be restored to service before leaving the premises and it should be done by reps of the occupants who are qualified to perform work. For liability purposes it is not recommended that firefighters do any of the work.
Dry pipe systems
used in locations where temps are expected to dip below 40F. All the pipes in this sustem are sloped to help drain the water in the system back to the main drain. Designed so that a small amount of air pressure above the dry pipe valve will hold back a much greater water pressure on the water supply side of the dry pipe valve. 20psi.
Riser
vertical piping to which the sprinkler valve, one way check valve, FDC, alarm valve, main drain, and other components are attached
Where sould light detectors be placed?
where other light sources are uncommon to prevent activation by nonfire conditions
When should pumpers be disconnected?
(From the FDC) Not until after the extinguishment has been confirmed by a thorough overhaul.
3 types of flame detectors
1 UV detectors 2 IR detectors 3 those that detect both
Rate of rise heat detectors are designed to initiate signal when rise in temp. exceeds
12 to 15 degrees in one minute
Common rating for heat detectors in lving spaces
135-174 degrees
The required air pressure for dry pipe systems is
20 psi above trip pressure
Sprinkler Temp ratings
black/uncoloured - ordinary - 135-170F White - intermediate - 175-225F Blue - High - 250-300F Red - Extra high - 325-375F Green - Very Extra High - 400-475F Orange - Ultra High - 500-575F Bad White Boys Rape Girls Often
Common identification for sprinklers
commonly identified by the temperature at which they are designed to operate
Detect heat over linear area parallel to detector
continuous line detector
Quick Response Mechanism
developed to enhance life safety. Offers increased surface area to collect the heat generated by a fire faster than the standard fusible link.
Drain pipe valve
device that keeps water out of the sprinkler piping until a fire actuates a sprinkler.
PIVA
does not use a plate with words, instead using a circular disk inside a flat plate on top of the valve housing. When the valve is open the disk is perpendicular to the surrounding plate. Operated with a built in crank.
3 different types of sprinkler systems
dry pipe wet pipe preaction deluge residential
WAter supply
every effort should be made to supply adequate to operating sprinkler system
Times when they are not effective
fires are too small to activate the system smoke generation reaches occupants before the system starts sleeping, drunk, handicapped persons occupy the building
Depending on size of room, a fire could burn a long time before activating
fixed temp. heat detectors
Types of Control Valves
four main types 1. OS & Y 2. Post Indicator 3. Wall Post Indicator 4. Post Indicator Valve Assembly
Detection device that holds electrical contacts apart with glass vial containing bulb with air bubble that bursts when heated to predetermined temp
frangible bulb
Normally held in place by a solder with a melting (fusing) temp.
fusible device
PIV
hollow metal post that houses the valve stem. Attached to the valve stem is a movable plate with the words OPEN or SHUT visible through a small glass window on the side of the housing. When not in use the operating handle is locked to the valve housing.
Fusible Link
involves a frame that is screwed into the sprinkler piping. Two levers press against the frame and a cap over the orifice from which the water flows. Fusible link holds the levers together until the link is melted by the heat of the fire. Deflector converts the standard 1/2" stream into water spray.
Inspectors Test Valve
is located in a remote part of the sprinkler system. Equipped with the same size orifice as one sprinkler and is used to to stimulate the activation of one sprinkler. The water from the test valve normally discharges outside the building.
Residential Sprinkler Systems
must have a pressure guage, (to check air pressure on dry pipe systems and water pressure on wet pipe), a flow detector and a means for draining and testing the system. some are equipped with a fire FDC, usually 1.5"
when should sprinkler valves should be closed
not until fire officers are convinced that further operations will simply waste water, produce heavy water damage or hamper progress. premature closing of the valve could cause the fire to intensify
In deluge systems, all sprinklers are
open all the time
OS & Y
outside stem and yoke valve, stem is visible beyond yoke when it is open.
Main drain Valve
part of every sprinkler system riser. the primary purpose of the main drain is to allow sprinkler service personnel to drain water from the system for maintenance purposes. Can also be used to check the system water supply.
Retardant chamber
part of the alarm check valve. This chamber catches excess water that may be sent through the alarm valve during momentary water pressure surges. Reduces chances of false activation
Sprinkler system may not function for the following reasons
partially or completely completely closed main water control valve Interruption to the water supply damaged or painted over sprinklers damaged pipes debris/sediment in the pipes failure of the secondary water supply tampering/vandalism sprinklers obstructed by objects stacked too close
Visible products of combustion detector; uses photoelectric cell coupled with tiny light source
photoelectric smoke detector - 2 ways: beam app. and refractory app.
Most common type of rate of rise detector
pneumatic rate of rise spot detector
Situations that sprinklers are effective in
preventing fire spread upwards in multistory buildings protecting the lives of occupants
