B Y
S TA N F O R D U N I V E R S I T Y
F I R E M A R S H A L’ S O F F I C E
AT
ENVIRONMENT HEALTH & SAFETY DEPT.
Fire Alarm System
Basics
JOE LEUNG University Fire Marshal Manager, Fire Safety Program
AARON MCCARTHY Senior Fire Protection Engineer ROBERT PORTERFIELD Fire Protection Engineer JENNIFER LEE Fire Protection Engineer JARNAIL DHALLA Fire Protection Engineer Assistant University Fire Marshal RALPH DURHAM University Fire Inspector FRANK “MO” MIRANDA Fire Systems Supervisor FRANK GARDNER Fire Systems Lead Technician RON MORRISON
Senior Fire Sprinkler Technician
CHRIS FRAZIER
ARTHUR “RICKEY” JOHNSON
RICH WILKINS JOE JACKSON MIKE ARMSTRONG JAMES BAXLEY JASON LOPEZ CARLOS GONZALEZ ZEEB “DAVID” GUARNEROS
RUDY GARAY BRANDON MCCLINTOCK Fire Sprinkler Technicians Fire Alarm Technicians Fire Extinguisher Technicians
Building C
JESSE TORRESFire Alarm Systems
Several main functions:
Provide a means to identify a developing fire through automatic
methods.
They alert building occupants to a fire condition and the need to
evacuate.
Another common function is the transmission of an alarm notification
signal to the fire department or other emergency response organization.
Fire alarm systems may also shut down electrical, air handling equipment
or special process operations, and they may be used to initiate automatic
suppression systems.
Fire Alarm Systems
Requirements
California Code of Regulations has 28 sections/titles.
Title 24: California Building Standards
Part 2: California Building Code
Part 3: California Electric Code
Part 9: California Fire Code
•
Chapter 9 lists basic requirements based on
occupancy type.
Depending on the anticipated fire scenario, building and use type,
number and type of occupants and criticality of contents and mission
There are 3 common types of systems: Conventional, Addressable,
Analog Addressable. Analog addressable type is not commonly used.
Fire Alarm System Types
Conventional
Lower initial equipment
costs.
Defined location of
fire/alarm not provided at
the panel or central station
Can be easier to program.
Limited expansion
capability.
Addressable
Easier to install.
More system status
information at the panel
and central station.
Input/Output programming
much more flexible.
Usually much more room
Conventional Systems
Wiring must be installed in a supervised manner either Class A, or Class
B with an EOLR. Alarm/Trouble conditions are annunciated by zone only.
Inspection is required to determine the device in alarm/trouble
Zone #1
4.7K EOLR 4.7K EOLRZone #2
NAC #1
FACP
Addressable Systems
Each point on the SLC loop is given a unique address
when installed. Alarm/Trouble conditions are annunciated
by a unique message for each device.
001
002
003
004
005
006
FACP
FIRE FIRE SILENT KNIGHT Addressable Pull Station Addressable Relay Module (Fan Shutdown) Addressable Heat Detector 4.7K EOLRNAC #1
Addressable Smoke Detector Addressable Input Module (Waterflow) Addressable Smoke DetectorFire Alarm System Principles
Manual fire detection is the oldest method of detection.
In the simplest form, a person yelling can provide fire
warning. In buildings, however, a person's voice may not
always transmit throughout the structure. For this reason,
manual alarm stations are installed. The general design
philosophy is to place stations within reach along paths of
escape/egress. It is for this reason that they can usually
be found near exit doors.
The advantage of manual alarm stations is that, upon
discovering the fire, they provide occupants with a
readily identifiable means to activate the building fire
alarm system. The alarm system can then serve in lieu of
the shouting person's voice. They are simple devices, and
can be highly reliable.
Fire Detection Principles
Fire Detection Principles
Automatic Detectors – Photoelectric
NFPA 72, Light Scattering Smoke Detection. The principle
of using a light source and a photosensitive sensor arranged so
that the rays from the light source do not normally fall onto the
photosensitive sensor. When smoke particles enter the light
path, some of the light is scattered by reflection and refraction
onto the sensor. The light signal is processed and used to
convey an alarm condition when it meets preset criteria.
Fire Detection Principles
Automatic Detectors – Photoelectric
A – Light Source B – Photo Sensor
In the normal case, the light from the light source on the left shoots straight across and misses the sensor.
When smoke enters the chamber, however, the smoke particles scatter the light and some amount of light hits the sensor.
Fire Detection Principles
Automatic Detectors – Ionization
This type is better at detecting the smaller amounts of smoke produced by flaming
fires.An ionization chamber consists of two plates with a voltage across them, along with a radioactive source of ionizing radiation.Inside the ionization detector is a small amount
(about 1/5000th of a gram) of Americium-241. This radioactive element has a half-life of 432 years, and is a good source of alpha particles.
NFPA 72, Ionization Smoke Detection. The principle of using a small amount of radioactive
material to ionize the air between two differentially charged electrodes to sense the presence of smoke particles. Smoke Particles entering the ionization volume decrease the conductance of the air by reducing ion mobility. The reduced conductance signal is processed and used to convey an alarm condition when it meets preset criteria.
Fire Detection Principles
Automatic Detectors – Ionization
The alpha particles generated by the americium ionize the oxygen and nitrogen atoms of the air in the chamber. To "ionize" means to "knock an electron off“ an atom ending with a free electron (with a negative charge) and an atom missing one electron (with a positive charge). The negative electron is attracted to the plate with a positive voltage, and the positive atom is attracted to the plate with a negative voltage (opposites attract, just like with magnets). The electronics in the smoke detector sense the small amount of electrical current that these electrons and ions moving toward the plates represent.
When smoke enters the ionization chamber, it disrupts this current -- the smoke particles attach to the ions and neutralize them. The smoke detector senses the drop in current between the plates and sets off the horn.
Fire Detection Principles
Automatic Detectors – Combination
NFPA 72, Combination Detector. A device that either responds to more than one of the fire
phenomena or employs more than one operating principle to sense one of these phenomena. Typical examples are a combination of a heat detector with a smoke detector or a combination of rate-of-rise and fixed temperature heat detector. This device has listings for each sensing method employed.
Combination detectors contain more than one element which responds to fire. These detectors may be designed to respond from either element, or from the combined partial or complete response of both elements. An example of the former is a heat detector that operates on both the rate-of-raise and fixed-temperature principles. Its advantage is that the rate-of-rise element will respond quickly to rapidly developing fire, while the fixed-temperature element will respond to a slowly developing fire when the detecting element reaches its set point temperature.
Building Notification
Notification Appliances
NFPA 72, Notification Appliance. A fire alarm system component such as a
bell, horn, speaker, light or text display that provides audible, tactile, or visible
outputs, or any combination thereof.
NFPA 72, Audible Notification Appliance. A notification appliance that alerts
by the sense of hearing.
NFPA 72, Visible Notification Appliance. A notification appliance that alerts
Fire Alarm Circuit Classes
NFPA 72, Classes. Initiating device circuits, notification appliance circuits, and
signaling line circuits shall be permitted to be designated as either Class A or
Class B, depending on their performance during non-simultaneous single
circuit fault conditions as specified by the following:
(1) Initiating device circuits and signaling line circuits that transmit an
alarm or supervisory signal, or notification appliance circuits that allow all
connected devices to operate during a single open or a non-simultaneous
single ground fault on any circuit conductor, shall be designated as Class A
(2) Initiating device circuits and signaling line circuits that do not transmit an
alarm or supervisory signal, or notification appliance circuits that do not
allow all connected devices to operate beyond the location of a single
open on any circuit conductor, shall be designated as Class B
Class B Initiating Device Circuit
4.7K EOLR
4.7K EOLR
Class B Notification Appliance Circuit
Conventional Class B Circuits
Single open circuit condition causes a trouble
on the panel and renders all devices beyond
the fault inoperative.
Class B Initiating Device Circuit
4.7K EOLR
4.7K EOLR
Class B Notification Appliance Circuit
Conventional System Class B Circuits
Class A Initiating Device Circuit
Class A Notification Appliance Circuit
Class A Circuits
End of line supervision resistors are not
necessary as the loop returns to the panel and
is driven from both ends.
Class A Initiating Device Circuit
Class A Notification Appliance Circuit
Class A Circuits
Single open circuit condition causes a trouble
on the panel. All devices on the loop remain
operative.
Licensing Requirements
Requirements for technicians per NFPA 72
State Certified in Fire/Life Safety or Electrician
NICET Certification
• FireFinder XLS (252 devices, expandable to 2500 devices)
• NFS-320 (318 devices)
• NFS2-640 (636 devices)
• NFS2-3030 (3,180 devices)
3 Types of Fire Alarm Signals
1. TROUBLE
• Local sounding (beeping) on FACP and Annunciators
• No horn/strobes sounding or flashing
• Low battery, smoke detector removed, ground fault, open horn circuit,
etc.
• Alarm Tech responds
2. SUPERVISORY
• Local sounding (beeping) on FACP and Annunciators
• No horn/strobes sounding or flashing
• Sprinkler valve closed, duct detector activated*, low-air on pre-action
system
• Fire Department responds
3. ALARM
• All horn/strobes sounding and flashing
• Building occupants to evacuate
• Smoke detector, manual pull, waterflow, duct detector, or heat detector
activated
SUFMO Fire Alarm Techs
Preventive Maintenance
Semiannual visual inspections Annual testing
Annual fire smoke damper testing (with HVAC)
Quarterly student evacuation drills (with Inspectors & FPEs) Monthly evacuation drills at child day care centers (with Inspectors) Annual elevator recall testing (with Kone A)
Construction Projects
Initial acceptance testing with FPEs per Stanford FDG and applicable codes
Final acceptance testing with FPEs and the Authority Having Jurisdiction (Santa Clara County or Palo Alto) Isolating system components for contractors to work (i.e., SESI)
Other Responsibilities
Respond to all fire system troubles 24/7 (On-Call)
Provide fire department assistance with technical issues or nuisance alarms Program fire alarm systems with laptop and proprietary software
Troubleshoot and repair fire alarm systems Maintain the Remote Monitoring Station
Providing services to
University Main Campus
Various off campus locations (Hopkins, Boathouse, Porter Drive, and others)
Fire smoke damper
There is a smoke
detector up there?
Remote Monitoring Station
Mesh network
Licensed FCC Radio Frequency (RF)
Antennas and receiving equipment in Building C
Dispatcher located at Palo Alto Communications (250 Hamilton)
Fire Department contacted by dispatcher directly
Over 300 monitored systems
ESF BLDG C
Remote Alarm Transmitter (RAT)
Mesh Network Concept
