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October 13, 2002

                             ET NEWS
================================================================
            A NEWSLETTER FOR ENGINEERING TECHNICIANS
----------------------------------------------------------------
Issue No. 68                                          10-13-2002
================================================================

Contents
--------
- News
- ET Journal
- NICET Test Dates
- AFAA Class Schedule
- Comments and Contacts

================================================================
NEWS
================================================================

Mark your calendar and plan to attend the next OAFAA (Oregon Automatic
Fire Alarm Association) meeting:
Tuesday, October 15, 2002, 9:00 to 11:00 AM at the Radisson Hotel, 1441
NE 2nd Ave., Portland.
Find out more at http://oafaa.org

----------------------------------------------------------------

I'm off to Anchorage this week.

Have fun!

Mike

================================================================
ET JOURNAL
================================================================

NICET Fire Alarm Systems Level II
33024* RADIANT ENERGY SENSING FIRE DETECTORS
--------------------------------------------

33024 is a Level II General Non-Core Work element.

The asterisk (*) following 33024 means crossover credit exists in
selected other fields/subfields for this work element. Read information
on crossover work elements in the Program Detail Manual on pages 4 and
5. You won't receive the crossover credit until you test in another
qualified sub-field for the first time.

33024 DESCRIPTION
Understand the basic principles of operation of flame flicker, infrared,
photoelectric, and ultraviolet flame sensing fire detectors and the
particular location and spacing requirements for flame detectors when
used on indoor and outdoor applications. (NFPA 72)

33024 REFERENCES:
NFPA 72
http://www.nfpa.org/catalog/product.asp?category%5Fname=&pid=7299

33024 DESCRIPTION BREAKDOWN:
"Understand the basic principles of operation of flame flicker,
infrared, photoelectric, and ultraviolet flame sensing fire detectors
and the particular location and spacing requirements for flame detectors
when used on indoor and outdoor applications."

NFPA 72-1999 1-4 Flame Detector. A radiant energy-sensing fire detector
that detects the radiant energy emitted by a flame. (See NFPA 72-1999
A-2-4.2.)

NFPA 72-1999 A-1-4 Flame detectors are categorized as ultraviolet,
single wavelength infrared, ultraviolet infrared, or multiple wavelength
infrared.

NFPA 72-1999 1-4 Wavelength. The distance between the peaks of a
sinusoidal wave. All radiant energy can be described as a wave having a
wavelength. Wavelength serves as the unit of measure for distinguishing
between different parts of the spectrum. Wavelengths are measured in
microns (uM), or Angstroms (Å).

NFPA 72-1999 A-1-4 The concept of wavelength is extremely important in
selecting the proper detector for a particular application. There is a
precise interrelation between the wavelength of light being emitted from
a flame and the combustion chemistry producing the flame. Specific
subatomic, atomic, and molecular events yield radiant energy of specific
wavelengths. For example, ultraviolet photons are emitted as the result
of the complete loss of electrons or very large changes in electron
energy levels. During combustion, molecules are violently torn apart by
the chemical reactivity of oxygen, and electrons are released in the
process, recombining at drastically lower energy levels, thus giving
rise to ultraviolet rations. Visible radiation is generally the result
of smaller changes in electron energy levels within the molecules of
fuel, flame intermediates, and products of combustion. Infrared
radiation comes from the vibration of molecules or parts of molecules
when they are in the superheated state associated with combustion. Each
chemical compound exhibits a group of wavelengths at which it is
resonant. These wavelengths constitute the chemical’s infrared spectrum,
which is usually unique to that chemical.

This interrelationship between wavelength and combustion chemistry
affects the relative performance of various types of detectors with
respect to various fires.

NFPA 72-1999 2-4.1 General. The purpose and scope of Section 2-4 shall
be to provide standards for the selection, location, and spacing of fire
detectors that sense the radiant energy produced by burning substances.
These detectors are categorized as flame detectors and spark/ember
detectors.

NFPA 72-1999 A-2-4.1 Radiant Energy. For the purpose of NFPA 72-1999,
radiant energy includes the electromagnetic radiation emitted as a
by-product of the combustion reaction, which obeys the laws of optics.
This includes radiation in the ultraviolet (0.1 to 0.35 uM), visible
(0.36 to 0.75 uM), and infrared (0.76 to 220 uM) portions of the
spectrum emitted by flames or glowing embers.

Conversion Factors: 1.0 uM = 1000 nM = 10,000 Å

NFPA 72-1999 2-4.2 Fire Characteristics and Detector Selection.
Following are operating principles for two types of detectors.
(a) Flame Detectors. Ultraviolet flame detectors typically use a vacuum
photodiode Geiger-Muller tube to detect the ultraviolet radiation that
is produced by a flame. The photodiode allows a burst of current to flow
for each ultraviolet photon that hits the active area of the tube. When
the number of current bursts per unit time reaches a predetermined
level, the detector initiates an alarm. 
A single wavelength infrared flame detector uses one of several
different photocell types to detect the infrared emissions in a single
wavelength band that are produced by a flame. These detectors generally
include provisions to minimize alarms from commonly occurring infrared
sources such as incandescent lighting or sunlight.

An ultraviolet/infrared (UV/IR) flame detector senses ultraviolet
radiation with a vacuum photodiode tube and a selected wavelength of
infrared radiation with a photocell and uses the combined signal to
indicate a fire. These detectors need exposure to both types of
radiation before an alarm signal can be initiated.

A multiple wavelength infrared (IR/IR) flame detector senses radiation
at two or more narrow bands of wavelengths in the infrared spectrum.
These detectors electronically compare the emissions between the band
and initiate a signal where the relationship between the two bands
indicates a fire.

(b) Spark/Ember Detectors. A spark/ember-sensing detector usually uses a
solid state photodiode or phototransistor to sense the radiant energy
emitted by embers, typically between 0.5 microns and 2.0 microns in
normally dark environments. These detectors can be made extremely
sensitive (microwatts), and their response times can be made very short
(microseconds).

NFPA 72-1999 2-4.2.1 The type and quantity of radiant energy-sensing
fire detectors will be determined based upon 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
flame. (See Figure A-2-4.2.1)

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°K (1727°C or
3240°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°F to 1830°F (398°C to 1000°C).

Most radiant energy detectors have some form of qualification circuitry
within them that uses time to help distinguish between spurious,
transient signals and legitimate fire alarms. These circuits become very
important where the anticipated fire scenario and the ability of the
detector to respond to that anticipated fire are considered. For
example, a detector that utilizes and integration circuit or a timing
circuit to respond to the flickering light from a fire might not respond
well to a deflagration resulting from the ignition of accumulated
combustible vapors and gases, or where the fire is a spark that is
traveling up to 328 ft/sec (100 m/sec) past the detector. Under these
circumstances, a detector that has a high speed response capability is
most appropriate. On the other hand, in applications where the
development of the fire is slower, a detector that utilizes time for the
confirmation of repetitive signals is appropriate. Consequently, the
fire growth rate should be considered in selecting the detector. The
detector performance should be selected to respond to the anticipated
fire.

The radiant emissions are not the only criteria to be considered. The
medium between the anticipated fire and the detector is also very
important. Different wavelengths of radiant energy are absorbed with
varying degrees of efficiency by materials that are suspended in the air
or that accumulate on the optical surfaces of the detector. Generally,
aerosols and surface deposits reduce the sensitivity of the detector.
The detection technology utilized should take into account those
normally occurring aerosols and surface deposits to minimize the
reduction of system response between maintenance intervals. It should be
noted that the smoke evolved from the combustion of middle and heavy
fraction petroleum distillates is highly absorptive in the ultraviolet
end of the spectrum. Where using this type of detection, the system
should be designed to minimize the effect of smoke interference on the
response of the detection system.

The environment and ambient conditions anticipated in the area to be
protected impact the choice of detector. All detectors have limitations
on the range of ambient temperatures over which they will respond,
consistent with their tested or approved sensitivities. The designer
should make certain that the detector is compatible with the range of
ambient temperatures anticipated in the area in which it is installed.
In addition, rain, snow, and ice attenuate both ultraviolet and infrared
radiation to varying degrees. Where anticipated, provisions should be
made to protect the detector form accumulations of these materials on
its optical surfaces.

NFPA 72-1999 2-4.2.2 The selection of the radiant energy-sensing
detectors will be based on the following.
(a) Matching of the spectral response of the detector to the spectral
emissions of the fire or fires to be detected
(b) Minimizing the possibility of spurious nuisance alarms from non-fire
sources inherent to the hazard area.

NFPA 72-1999 2-4.3.1.1 Radiant energy-sensing fire detectors will be
employed consistent with the listing or approval and the inverse square
law, which defines the fire size versus distance curve for the detector.

NFPA 72-1999 2-4.3.2.1 Spacing Considerations for Flame Detectors.
The location and spacing of detectors will be the result of an
engineering evaluation that takes into consideration:
(1) Size of the fire that is to be detected
(2) Fuel involved
(3) Sensitivity of the detector
(4) Field of view of the detector
(5) Distance between the fire and the detector
(6) Radiant energy absorption of the atmosphere
(7) Presence of extraneous sources of radiant emissions
(8) Purpose of the detection system
(9) Response time required

NFPA 72-1999 A-2-4.3.2.1 The following are types of application for
which flame detectors are suitable.
(1) High-ceiling, open-spaced buildings such as warehouses and aircraft
hangers
(2) Outdoor or semioutdoor 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 the
following.
(1) Sunlight
(2) Lightning
(3) X-rays
(4) Gamma rays
(5) Cosmic rays
(6) Ultraviolet radiation from arc welding
(7) Electromagnetic interference (EMI, RFI)
(8) Hot objects
(9) Artificial lighting.

NFPA 72-1999 2-4.3.2.5 Because flame detectors are line-of-sight
devices, special care must be taken to ensure that their ability to
respond to the required area of fire in the zone that is to be protected
is not compromised by the presence of intervening structural members or
other opaque objects or materials.


THE INFORMATION HEREIN 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
================================================================

From the NICET web site http://63.70.211.210/cfdocs/nicetschedule1.cfm:
"It is anticipated that the 2003 schedule will be very similar to the
2002 schedule. The dates for the first test cycle of 2003 will be
January 26, February 23 and March 23. The first application postmark
deadline will be December 1, 2002. This postmark deadline must be used
by all examinees testing in the first test cycle of 2003 until such time
as the schedule for your preferred sessions is established."

OREGON
------
PCC Sylvania, Portland;
Test 11/16/02. Postmark deadline 9/28/02.
Test TBA/03. Postmark deadline TBA/03.

Clackamas Community College, Oregon City;
Test 11/16/02. Postmark deadline 9/28/02.
Test TBA/03. Postmark deadline TBA/03.

WASHINGTON
----------
Bates Technical College, Tacoma;
Test 12/14/02. Postmark deadline 10/26/02.
Test TBA/03. Postmark deadline TBA/03.

Walla Walla Community College;
Test 10/19/02. Postmark deadline 8/31/02.
Test TBA/03. Postmark deadline TBA/03.

Spokane Community College;
Test 11/16/02. Postmark deadline 9/28/02.
Test TBA/03. Postmark deadline TBA/03.

For a complete list of all test centers and test dates, visit
http://63.70.211.210/cfdocs/nicetschedule.cfm

================================================================
AFAA CLASS SCHEDULE 
================================================================

------------------
October 14-16, 2002 Anchorage, AK
------------------
Intermediate Fire Alarm Seminar 10/14-16
http://www.afaa.org/afaa/PDF/INT_ANC_Oct2002.pdf

------------------
October 22-24, 2002 El Paso, TX - Co-sponsored by Texas Fire Alarm
Association
------------------
Intermediate Fire Alarm Seminar.
http://www.afaa.org/afaa/PDF/IntFA_ElPaso_Oct2002.pdf

------------------
October 28-30, 2002 Brockton, MA - Sponsored by AFAA of New England
------------------
Intermediate Fire Alarm Seminar 10/28-30
http://www.afaa.org/afaa/PDF/IntFA_NE_Oct2002.pdf

------------------
November 4-7, 2002 Anaheim, CA - Sponsored by CAFAA
------------------
Fire Alarm System Testing and Inspections Seminar 11/4
http://www.afaa.org/afaa/PDF/INT_TI_CAFAA_ANAHEIM_November2002.pdf
Intermediate Fire Alarm Seminar 11/5-7 SOLD OUT!

------------------
November 12-14, 2002 Anaheim, CA - Sponsored by CAFAA
------------------
Intermediate Fire Alarm Seminar
http://www.afaa.org/afaa/PDF/IntFA_CAFAA_Anaheim2_Nov2002.pdf

------------------
November 12-15, 2002 Richmond, VA - Sponsored by Virginia AFAA  
------------------
Fire Alarm System Testing and Inspections Seminar 11/12
http://www.afaa.org/afaa/PDF/INT_TI_Richmond_Nov02.pdf
Intermediate Fire Alarm Seminar 11/13-15
http://www.afaa.org/afaa/PDF/INT_TI_Richmond_Nov02.pdf  

------------------
November 19-21, 2002 Salt Lake City, UT
------------------
Intermediate Fire Alarm Seminar.
http://www.afaa.org/afaa/PDF/IntFA_SaltLakeCity_Nov20021.pdf

------------------
December 2-5, 2002 Orlando, FL  
------------------
Fire Alarm System Testing and Inspections Seminar 12/2
http://www.afaa.org/afaa/PDF/INT_TI_Orlando_Dec2002.pdf
Intermediate Fire Alarm Seminar 12/3-5
http://www.afaa.org/afaa/PDF/INT_TI_Orlando_Dec2002.pdf

------------------
December 3-5, 2002 Seattle, WA
------------------
Advanced Fire Alarm Seminar. More information will be available soon!

------------------
February 4-6, 2003 Orlando, FL
------------------
Advanced Fire Alarm Seminar. More information will be available soon!

------------------
February 19-21, 2003 Raleigh, NC 
------------------
Intermediate Fire Alarm Seminar. More information will be available
soon!

================================================================
COMMENTS AND CONTACTS
================================================================

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NATIONAL INSTITUTE FOR CERTIFICATION IN ENGINEERING TECHNOLOGIES
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The AFAA acronym found herein refers to:
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This reprinted material is not the complete and official position of the NFPA on the referenced subject, which is represented only by the standard in its entirety.