NEWS FOR ENGINEERING TECHNICIANS
Volume 2 Issue 22 6-2-2002
- ET Journal
- Test Dates
- Class Schedule
I set up a new automated email distribution list to deliver the email
version of ET News. If it works, I will be free at last of the attbi.com
I recently purchased the new NFPA POCKET GUIDE TO FIRE ALARM SYSTEM
INSTALLATION, by Merton W. Bunker Jr. and Richard J. Roux. Priced at
$26.00 ($23.40 for NFPA members plus $5.95 shipping), it's a good
resource for anyone working in the fire alarm industry and a great
resource for persons preparing for a NICET exam. At 5.75" X 3.25" X 1"
and over 600 pages, this pocket guide will be a tight fit in your
pocket, but it's an excellent addition to your briefcase or tool bag.
The guide includes tables, illustrations, and symbols from NFPA 70, 72,
101, 170, and many engineering books, standards, and reference manuals.
Contents (in the authors' words):
Section I DEFINITIONS contains selected definitions from NFPA 70, 72,
Section II FUNDAMENTALS offers information relating to major common
system requirements, including system types, power supply requirements,
battery calculations, circuit class and style, monitoring for integrity,
circuits extending beyond one building, alarm sequence, control
functions, signals, and survivability.
Section III INITIATING DEVICES provides various requirements for the
spacing, locations, and installation of commonly used initiating
devices. Initiating devices covered include heat detectors, line-type
heat detectors, and smoke detectors. This information is frequently
needed in the field for verification of proper device placement.
Section IV NOTIFICATION APPLIANCES provides basic data to assist the
user in design, spacing, location, and installation of both audible and
visible notification appliances. Included are tables and figures showing
sound pressure levels, useful relationships, light criteria, and visible
equivalency. This information, which is commonly used by design and
installation personnel, is useful throughout the design and installation
Section V SUPERVISING STATIONS is a collection of basic requirements for
supervising station systems and related communications methods. Included
are figures and tables showing the criteria for several supervising
station types, transmission methods, loading, and other criteria.
Section VI INSPECTION, TESTING, AND MAINTENANCE includes test checklists
and tables showing test methods, testing and visual inspection
frequencies, and voltage criteria for nickel cadmium and lead acid
batteries. This section contains tables and schedules as well as basic
information necessary for the performance of overall fire alarm system
testing. This information is needed to establish verification of test
methods in the field.
Section VII WIRING provides essential data for the designer and
installer relevant to wiring methods, conductors, cable substitutions,
and conduit and raceway systems. This section contains voltage drop and
loop resistance information; conductor and cable data; conduit and box
fill requirements; and specifications for power-limited, Class 2, and
Class 3 power supplies. For explanation, correct and incorrect wiring
methods are illustrated
Section VIII DOCUMENTATION AND DRAWINGS provides reference material and
useful information on working plans for fire alarm systems. Included is
a collection of commonly used symbols for electrical, fire alarm, and
fire protection devices from various sources, including NFPA 170 and
NECA 100-99. It identifies the information needed on drawings and
illustrates commonly used symbols for devices, fire alarm control units,
and appliances. This information is critical to anyone who must
interpret the notations of fire alarm system elements on system
documentation. This information is included in an effort to encourage
the use of standardized symbols on fire alarm drawings.
Section IX USEFUL TABLES, FORMULAS, AND FIGURES provides the user with
conversion factors between SI and U.S. customary units of measurement.
This information is especially important since most NFPA codes and
standards are being revised to use SI units. Common conversion factors
for length, area, volume, light, and temperature are included. General
engineering formulas that are useful to anyone in the field who needs to
initiate calculations or verify estimates are provided. Basic data are
provided to assist in identifying device and appliance characteristics.
This information is needed by anyone associated with the design,
installation, or commissioning of a fire alarm system.
Section X USEFUL CONTACTS is a listing of organizations and contact
information useful to designers, installers, and authorities having
NICET Fire Alarm Systems Level II
33006 DETECTION METHODS
33006 is a Level II General Core Work element.
All Level II General Core Work Elements constitute a mandatory
requirement for achieving certification at Levels III and IV.
Know the basic principles of automatic fire detectors listed in NFPA 72.
Select the best type of detection for the
application and ambient conditions. (NFPA 72 and 101)
33006 DESCRIPTION BREAKDOWN:
"Know the basic principles of automatic fire detectors listed in NFPA
NFPA 72-1999 1-4 Cloud Chamber Smoke Detection. The principle of using
an air sample drawn from the protected area into a high humidity chamber
combined with a lowering of chamber pressure to create an environment in
which the resultant moisture in the air condenses on any smoke particles
present, forming a cloud, The cloud density is measured by a
photoelectric principle. The density signal is processed and used to
convey an alarm condition when it meets preset criteria.
NFPA 72-1999 1-4 Fixed Temperature Detector. A device that responds when
its operating element becomes heated to a predetermined level.
NFPA 72-1999 A-1-4 Fixed Temperature Detector. The difference between
the operating temperature of a fixed temperature device and the
surrounding air temperature is proportional to the rate at which the
temperature is rising. The rate is commonly referred to as thermal lag.
The air temperature is always higher than the operating temperature of
Typical examples of fixed temperature-sensing elements are as follows.
(a) Bimetallic. A sensing element comprised of two metals having
different coefficients of thermal expansion arranged so that the effect
is deflection in one direction when heated and in the opposite direction
(b) Electrical Conductivity. A line-type or spot-type sensing element
whose resistance varies as a function of temperature.
(c) Fusible Alloy. A sensing element of a special composition (eutectic)
metal that melts rapidly at the rated temperature.
(d) Heat-Sensitive Cable. A line-type device whose sensing element
comprises, in one type, two current-carrying wires separated by
heat-sensitive insulation that softens at the rated temperature, thus
allowing the wires to make electrical contact. In another type, a single
wire is centered in a metallic tube, and the intervening space is filled
with a substance that, at a critical temperature, becomes conductive,
thus establishing electrical contact between the tube and the wire.
(e) Liquid Expansion. A sensing element comprising a liquid capable of
marked expansion in volume in response to temperature increase.
NFPA 72-1999 1-4 Flame Detector. A radiant energy-sensing fire detector
that detects the radiant energy emitted by a flame (See A-5-4.2.)
NFPA 72-1999 A-1-4 Flame detectors are categorized as ultraviolet,
single wavelength infrared, ultraviolet infrared, or multiple wavelength
NFPA 72-1999 1-4 Heat Detector. A fire detector that senses heat
produced by burning substances. Heat is the energy produced by
combustion that causes substances to rise in temperature.
NFPA 72-1999 1-4 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
NFPA 72-1999 A-1-4 Ionization smoke detection is more responsive to
invisible particles (smaller than 1 micron in size) produced by most
flaming fires. It is somewhat less responsive to the larger particles
typical of most smoldering fire. Smoke detectors utilizing the
ionization principle are usually of the spot type.
NFPA 72-1999 1-4 Photoelectric Light Obscurations Smoke Detection. The
principle of utilizing a light source and a photosensitive sensor onto
which the principal portion of the source emissions is focused. When
smoke particles enter the light path, some of the light is scattered and
some is absorbed, thereby reducing the light reaching the receiving
sensor. The light reduction signal is processed and used to convey an
alarm condition when it meets preset criteria.
NFPA 72-1999 A-1-4 Photoelectric Light Obscuration Smoke Detection. The
response of photoelectric light obscuration smoke detectors is usually
not affected by the color of smoke. Smoke detectors utilizing the light
obscuration principle are usually of the line type. These detectors are
commonly refereed to as "projected beam smoke detectors."
NFPA 72-1999 A-1-4 Photoelectric light-scattering smoke detection is
more responsive to visible particles (larger than 1 micron in size)
produced by most smoldering fires. It is somewhat less responsive to the
smaller particles typical of most flaming fires. It is also less
responsive to black smoke than to lighter colored smoke. Smoke detectors
that use the light-scattering principle are usually of the spot type.
NFPA 72-1999 1-4 Rate Compensation Detector. A device that responds when
the temperature of the air surrounding the device reaches a
predetermined level, regardless of the rate of temperature rise.
NFPA 72-1999 A-1-4 Rate Compensation Detector. A typical example is a
spot-type detector with a tubular casing of a metal that tends to expand
lengthwise as it is heated and an associated contact mechanism that
closes at a certain point in the elongation. A second metallic element
inside the tube exerts an opposing force on the contacts, tending to
hold them open. The forces are balanced in such a way that, on a slow
rate-of-temperature rise, there is more time for heat to penetrate to
the inner element, which inhibits contact closure until the total device
has been heated to its rated temperature level. However, on a fast
rate-of-temperature rise, there is not as much time for heat to
penetrate to the inner element, which exerts less of an inhibiting
effect so that contact closure is achieved when the total device has
been heated to a lower temperature. This, in effect, compensates for
NFPA 72-1999 1-4 Rate-of-Rise Detector. A device that responds when the
temperature rises at a rate exceeding a predetermined value.
NFPA 72-1999 A-1-4 Typical examples of rate-of-rise detectors are as
(a) Pneumatic Rate-of Rise Tubing. A line-type detector comprising
small-diameter tubing, usually copper, that is installed on the ceiling
or high on the walls throughout the protected area. The tubing is
terminated in a detector unit containing diaphragms and associated
contacts set to actuate at a predetermined pressure. The system is
sealed except for calibrated vents that compensate for normal changes in
(b) Spot-Type Pneumatic Rate-of-Rise Detector. A device consisting of an
air chamber, a diaphragm, contacts, and a compensating vent in a single
enclosure. The principle of operation is the same as that described for
pneumatic rate-of-rise tubing.
(c) Electrical Conductivity-Type Rate-of-Rise Detector. A line-type or
spot-type sensing element whose resistance changes due to a change in
temperature. The rate of change of resistance is monitored by associated
control equipment, and an alarm is initiated when the rate of
temperature increase exceeds a preset value.
NFPA 72-1999 1-4 Smoke Detector. A device that detects visible or
invisible particles of combustion.
"Select the best type of detection for the application and ambient
NFPA 72-1999 2-3.6.1 The selection and placement of smoke detectors will
take into account both the performance characteristics of the detector
and the areas into which the detectors are to be installed to prevent
nuisance alarms or improper operation after installation. NFPA 72-1999
2-188.8.131.52 through 2-184.108.40.206 will apply.
NFPA 72-1999 2-220.127.116.11 The location of smoke detectors will be based on
an evaluation of potential ambient sources of smoke, moisture, dust, or
fumes, and electrical or mechanical influences to minimized nuisance
NFPA 72-1999 A-2-18.104.22.168 Smoke detectors can be affected by electrical
and mechanical influences and by aerosols and particulate matter found
in protected spaces. The location of detectors should be such that the
influences of aerosols and particulate matter from sources such as those
in NFPA 72-1999 Table A-2-22.214.171.124(a) are minimized. Similarly, the
influences of electrical and mechanical factors shown in NFPA 72-1999
Table A-2-126.96.36.199(b) should be minimized. While it might not be possible
to isolate environmental factors totally, an awareness of these factors
during system layout and design favorably affects detector performance.
NFPA 72-1999 2-188.8.131.52 The effect of stratification below the ceiling
will be considered. The guidelines in Appendix B will be permitted to be
NFPA 72-1999 A-2-3.2 The person designing an installation should keep in
mind that, in order for a smoke detector to respond, the smoke has to
travel from the point of origin to the detector. In evaluating any
particular building or location, likely fire locations should be
determined first. From each of these points of origin, paths of smoke
travel should be determined. Wherever practical, actual field tests
should be conducted. The most desired locations for smoke detectors are
the common points of intersection of smoke travel from fire locations
throughout the building.
NOTE: This is one of the reasons that specific spacing is not assigned
to smoke detectors by the testing laboratories.
NFPA 72-1999 A-2-3.4.1 For operation, all types of smoke detectors
depend on smoke entering the sensing chamber or light beam. Where
sufficient concentration is present, operation is obtained. Since the
detectors are usually mounted on the ceiling, response time depends on
the nature of the fire. A hot fire rapidly drives the smoke up to the
ceiling. A smoldering fire, such as in a sofa, produces little heat;
therefore, the time for smoke to reach the detector is increased.
NFPA 72-1999 A-2-3.4.3 In high ceiling areas, such as atriums, where
spot-type smoke detectors are not accessible for periodic maintenance
and testing, projected beam-type or air sampling-type detectors should
be considered where access could be provided.
NFPA 72-1999 2-3.6.5 Where smoke detectors are installed to actuate a
suppression system, NFPA 13 will apply.
NFPA 72-1999 A-2-3.6.5 For the most effective detection of fire in high
rack storage areas, detectors should be located on the ceiling above
each aisle and at intermediate levels in the racks. This is necessary to
detect smoke that is trapped in the racks at an early stage of fire
development, when insufficient thermal energy is released to carry the
smoke to the ceiling. Earliest detection of smoke is achieved by
locating the intermediate level detectors adjacent to alternate pallet
sections as shown in Figures A-2-3.6.5 (a) and A-2-3.6.5 (b). The
detector manufacturer's recommendations and engineering judgment should
be followed for specific installations. A projected beam-type detector
may be permitted to be used in lieu of a single row of individual
spot-type smoke detectors. Sampling ports of an air sampling-type
detector may be permitted to be located above each aisle to provide
coverage equivalent to the location of spot-type detectors. The
manufacturer's recommendations and engineering judgment should be
followed for specific installations.
A projected beam-type detector is permitted to be used in lieu of a
single row of individual spot-type smoke detectors.
Sampling ports of an air sampling-type detector can be permitted to be
located above each aisle to provide coverage that is equivalent to the
location of spot-type detectors. The manufacturer's recommendations and
engineering judgment should be followed for the specific installation.
NFPA 72-1999 2-4.2.1 The type and quantity of radiant energy-sensing
fire detectors will be determined based on the performance
characteristics of the detector and an analysis of the hazard, including
the burning characteristics of the fuel, the fire growth rate, the
environment, the ambient conditions, and the capabilities of the
extinguishing media and equipment.
NFPA 72-1999 A-2-4.2.1 The radiant energy from a flame or spark / ember
is comprised of emissions in various bands of the ultraviolet, visible,
and infrared portions of the spectrum. The relative quantities of
radiation emitted in each part of the spectrum are determined by the
fuel chemistry, the temperature, and the rate of combustion. The
detector should be matched to the characteristics of the fire.
Almost all materials that participate in flaming combustion emit
ultraviolet radiation to some degree during flaming combustion, whereas
only carbon-containing fuels emit significant radiation at the 4.35
micron (carbon dioxide) band used by many detector types to detect a
The radiant energy emitted from an ember is determined primarily by the
fuel temperature (Planck's Law Emissions) and the emissivity of the
fuel. Radiant energy from an ember is primarily infrared and, to a
lesser degree, visible in wavelength. In general, embers do not emit
ultraviolet energy in significant quantities (0.1 percent of total
emissions) until the ember achieves temperatures of 2000 degrees K (1727
degrees C or 3240 degrees F). In most cases, the emissions are included
in the band of 0.8 microns to 2.0 microns, corresponding to temperatures
of approximately 750 degrees F to 1830 degrees F (398 degrees C to 1000
NFPA 72-1999 A-2-184.108.40.206 The following are types of applications for
which flame detectors are suitable:
1. High-ceiling, open-spaced buildings such as warehouses and aircraft
2. Outdoor or semi-outdoor areas where winds or draughts can prevent
smoke from reaching a heat or smoke detector.
3. Areas where rapidly developing flaming fires can occur, such as
aircraft hangers, petrochemical production, storage, and transfer areas,
natural gas installations, paint shops, or solvent areas.
4. Areas needing high fire risk machinery or installations, often
coupled with an automatic gas extinguishing system.
5. Environments that are unsuitable for other types of detectors.
Some extraneous sources of radiant emissions that have been identified
as interfering with the stability of flame detectors include:
4. Gamma rays
5. Cosmic rays
6. Ultraviolet radiation from arc welding
7. Electromagnetic interference (EMI, RFI)
8. Hot objects
9. Artificial lighting.
THE INFORMATION IN ET JOURNAL IS PROVIDED AS A GUIDE ONLY AND IS
INTENDED TO ASSIST YOU IN PREPARING FOR AN EXAM. IT IS NOT INTENDED TO
BE INCLUSIVE OF ALL INFORMATION THAT MAY BE ON AN EXAM BUT RATHER IT IS
INTENDED TO BE A SMALL SAMPLE OF THE KIND OF MATERIAL THAT YOU MAY BE
EXPECTED TO KNOW.
NICET TEST DATES
PCC Sylvania, Portland;
Test 7/27/02. Postmark deadline 6/8/02.
Test 11/16/02. Postmark deadline 9/28/02.
Clackamas Community College, Oregon City;
Test 6/22/02. Postmark deadline 5/4/02.
Test 9/14/02. Postmark deadline 7/27/02.
Bates Technical College, Tacoma;
Test 9/14/02. Postmark deadline 7/27/02.
Test 12/14/02. Postmark deadline 10/26/02.
Walla Walla Community College;
Test 7/25/02. Postmark deadline 6/8/02.
Test 10/19/02. Postmark deadline 8/31/02.
Spokane Community College;
Test 8/24/02. Postmark deadline 7/6/02.
Test 11/16/02. Postmark deadline 9/28/02.
For a complete list of all test centers and test dates, visit
Clackamas Community College is sponsoring a 16-hour NICET Test
>> 7-13-2002 8 a.m. - 5 p.m. NICET Certification application process and
Fire Alarm Systems Level I Element Review.
>> 7-20-2002 8 a.m. - 5 p.m. Fire Alarm Systems Level II Element Review.
Clackamas Community College
19600 South Molalla Avenue
Oregon City, OR 97045
Michael B. Baker SET
Dean Reed and Associates is sponsoring a 16-hour NICET Test Preparation
>> 6-22-02 8 a.m. to 5 p.m. NICET Certification application process and
Fire Alarm Systems Level I Element Review.
>> 6-29-02 8 a.m. to 5 p.m. Fire Alarm Systems Level II Element Review.
Pinkerton Systems Integration
15404 53rd Ave South
Seattle, WA 98188
[Near South Center]
Dean Reed CET
(206) 935-8950 voice/fax
(206) 953-8240 cell
The ET Newsletter is also available on the web http://etnews.org
ET News PHP/MySQL site by Doug Hockinson: http://metrodenver.org
Subscribe --> mailto:firstname.lastname@example.org?subject=subscribe
Send comments: mailto:email@example.com?subject=etnews_comments
Step-by-step guide to NICET Certification in Fire Alarm Systems
http://www.etnews.org/docs/stepbystep.pdf [requires Acrobat Reader]
Some information found in this email message is reprinted with
permission from one or more of the following; NFPA 70 National
Electrical CodeR, NFPA 72 National Fire Alarm CodeR, and NFPA 101R Life
Safety CodeR, Copyright C National Fire Protection Association, Quincy,
MA 02269. This reprinted material is not the complete and official
position of the National Fire Protection Association on the referenced
subject, which is represented only by the standard in its entirety.
National Electrical CodeR, NECR, National Fire Alarm CodeR, Life Safety
CodeR, and 101R are registered trademarks of the National Fire
Protection Association, Inc., Quincy, MA 02269.
The NICET acronym belongs to:
National Institute for Certification in Engineering Technologies
1420 King Street || Alexandria, VA 22314-2794 || (888) 476-4238
ET News Copyright(c) 2002 by Michael B Baker all rights reserved