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August 3, 2003

                             ET NEWS
================================================================
        NEWS AND INFORMATION FOR ENGINEERING TECHNICIANS
----------------------------------------------------------------
Issue No. 110          http://www.etnews.org            8-3-2003
================================================================

Contents
--------
- News
- ET Journal
- NICET Test Dates
- AFAA Class Schedule
- Comments & Acknowledgements

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

Seminars coming to a city near you:

------------------
August 19-21, 2003 Denver, CO - Co-sponsored by Rocky Mtn AFAA
------------------
Intermediate Fire Alarm Seminar
http://www.afaa.org/afaa/PDF/IntFA_Denver_August2003.pdf

------------------
August 21-22, 2003 Oklahoma City, OK - Conducted by OK AFAA
------------------
Automatic Fire Detection and Fire Alarm Systems Seminar
http://www.afaa.org/afaa/PDF/Auto_Fire_Detection_OKC_August_2003
.pdf

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

I'll see you in Happyrock this week.

Have fun!

Mike
mailto:mbbaker@etnews.org

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

NICET Fire Alarm Systems Level IV
38006 HEAT DETECTORS
---------------------------------

38006 is a Level IV Special work element.

38006 DESCRIPTION
Understand the theory of operation of heat detectors of the fixed
temperature, rate compensation, and rate-of-rise principle of
operation. Know the proper and improper applications of heat
detectors, the way each type of heat detector responds to a fire,
and the methods used by testing labs to determine the
suitability of a heat detector for listing. (NFPA 72, UL-521,
Fire Protection Handbook)

38006 REFERENCES
NFPA 72
http://www.etnews.org/index.php?s=461&bid=5

UL-521
http://www.comm-2000.com/productdetails.aspx?sendingPageType=Big
Browser&CatalogID=Standards&ProductID=UL521_7_S_19990219(ULStand
ards2)

Fire Protection Handbook
http://www.etnews.org/index.php?s=461&bid=7

38006 DESCRIPTION BREAKDOWN
Understand the theory of operation of heat detectors of the fixed
temperature, rate compensation, and rate-of-rise principle of
operation. Know the proper and improper applications of heat
detectors, the way each type of heat detector responds to a fire,
and the methods used by testing labs to determine the suitability
of a heat detector for listing.

Glossary of terms

Fixed Temperature Detector. A device that responds when its
operating element becomes heated to a predetermined level. 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 and
is commonly referred to as "thermal lag". The air temperature is
always higher than the operating temperature of the device.

Examples of fixed temperature sensing elements include:
 o Bimetallic
 o Electrical conductivity
 o Fusible alloy
 o Heat sensitive cable
 o Liquid expansion

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.
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 thermal lag.

Heat-sensing fire detector advantages:
 o Least expensive fire detector
 o Lowest nuisance alarm rate

Heat sensing fire detectors disadvantages:
 o Slowest to respond to fire

Principle of operation
----------------------

Fixed Temperature Heat Detector:
Bi-metallic:  A sensing element comprised of two dissimilar
metals having different coefficients of thermal expansion
arranged such that the element will be deflected in one direction
when heated and deflected in the opposite direction when cooled.
This is considered a restorable spot-type fixed-temperature heat-
sensing fire detector.

Electrical Conductivity: A sensing element comprised of an
electrical resistor (thermistor) exhibiting predictable
electrical resistance as a function of temperature. This is
considered a restorable line-type fixed-temperature heat-sensing
fire detector.

Fusible Alloy: A sensing element of metal alloy which melts at
its rated temperature. This is considered a non-restorable spot-
type fixed temperature heat-sensing fire detector.

Heat-sensitive cable: A sensing element comprised, in one type,
of two current-carrying wires separated by a heat-sensitive
insulation which softens at its rated temperature, allowing the
wires to make electrical contact. In another type, a single wire
is centered in a metal tube. The intervening space is filled with
a substance which becomes conductive at its rated temperature,
allowing electrical contact between the tube and wire. This is
considered a non-restorable line-type fixed-temperature heat-
sensing fire detector.

Rate-Compensation Detector: A spot-type fixed-temperature heat
detector with an additional tubular contact mechanism that closes
as it elongates in the presence of fire. A second metallic
element inside the tube exerts a force opposing the force on the
contacts tending to hold them open. These forces are balanced
such that on a slow rate of temperature rise, more time is
allowed for heat to penetrate to the inner element, which
inhibits contact closure until the entire device is heated to its
rated temperature. In the case of a rapid temperature increase,
there is less time for the heat to penetrate to the inner element
exerting less inhibiting force and allowing contact closure when
the entire device is heated to a lower temperature. This
effectively compensates for thermal lag.  This is considered a
restorable heat-sensing fire detector.

Rate-of-Rise Heat Detector:
Pneumatic Tubing: A line-type detector comprised of small
diameter tubing, usually copper, installed on the ceiling or high
on the walls throughout the protected area. The tubing is
terminated in a detector unit which includes diaphragms connected
to electrical contacts set to actuate at the pressure correlating
to a predetermined temperature. The system is sealed except for
calibrated vents which compensate for normal changes in ambient
temperature. This is considered a restorable line-type rate-of-
rise heat-sensing fire detector.

Pneumatic chamber: A device consisting of an air chamber,
diaphragm, contacts, and compensating vent in a single enclosure.
The principle of operation is the same as that described in
Pneumatic Tubing. This is considered a restorable spot-type
rate-of-rise heat-sensing fire detector. This type of detector
may incorporate an element using a fusible alloy (eutectic weld)
arranged to melt (fuse) at a fixed temperature causing the
contacts to close. The fixed temperature element of this
combination detector is non-restorable. 

A rate-of-rise heat detector is a device that will respond when
the temperature rises at a rate exceeding a predetermined amount
(12 to 15 degrees Fahrenheit per minute).

A heat detector is best suited for fire detection in a small
confined space where rapidly building high-heat-output fires are
expected; in areas where ambient conditions would not allow the
use of other fire detection devices; or where speed of detection
is not a prime consideration.

Rate-of-rise heat detectors are designed to compensate for the
normal changes in ambient temperature [less than 12 degrees
Fahrenheit (6.7 degrees Centigrade) per minute] that are expected
under non-fire conditions.

A rate compensation detector responds when the temperature of the
surrounding air reaches its rated set point, regardless of the
rate of temperature rise.

NFPA 72-1999 A-2-2.4.1 Heat detector fire test layout. At UL(r),
a test fire is fueled by 190 proof denatured alcohol in a pan
located approximately 3 feet above the floor. The test assumes
that the heat detectors are to be installed in a pattern of one
or more squares, each side of which equal to the maximum spacing
as determined in the test.

An alcohol fire of sufficient size is built to fuse a sprinkler
head rated for 160°F two minutes after ignition. The test heat
detector, installed at the maximum rated distance from the fire,
is required to operate before the sprinkler head.

The detector to be tested is placed at a corner of the square
such that it is positioned at the farthest possible distance from
the fire while remaining within the square. Thus, the distance
from the detector to the fire is always the test spacing
multiplied by .7.

For a heat detector to receive a listed spacing of 50 feet, it
is required to operate before the 160°F sprinklers do while
installed 35 feet (.7 times 50 feet) from the test fire.

See NFPA 72-1999 Figure A-2-2.4.1 and Figure A-2-2.4.1(c).

NFPA 72-1999 2-2.1.1.1 Spot-type, fixed-temperature or rate-
compensated, heat-sensing fire detectors will be classified as to
its temperature of operation and marked with a color code in
accordance with Table 2-2.1.1.1.
Except heat-sensing fire detectors which include a field
adjustable alarm threshold that are marked with its temperature
range.

NFPA 72-1999 2-2.3 The temperature range of heat-sensing
detectors will be at least 20°F above the maximum expected
ceiling temperature. 


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
================================================================

OREGON
------
OR1 PCC Sylvania, Portland;
Test 11/15/03. Postmark deadline 9/27/03.
Test ??/??/04. Postmark deadline 12/1/03.

OR2 Clackamas Community College, Oregon City;
Test 9/27/03. Postmark deadline 8/9/03.
Test 11/15/03. Postmark deadline 9/27/03.

These dates are from the NICET web site. For a complete list of
all test centers and test dates, visit:
http://63.70.211.210/cfdocs/nicetschedule.cfm

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

------------------
August 18-19, 2003 Tulsa, OK - Conducted by OK AFAA
------------------
Automatic Fire Detection and Fire Alarm Systems Seminar
http://www.afaa.org/afaa/PDF/Auto_Fire_Detection_OKC_August_2003
_Tulsa.pdf

------------------
August 19-21, 2003 Denver, CO - Co-sponsored by Rocky Mtn AFAA
------------------
Intermediate Fire Alarm Seminar
http://www.afaa.org/afaa/PDF/IntFA_Denver_August2003.pdf

------------------
August 21-22, 2003 Oklahoma City, OK - Conducted by OK AFAA
------------------
Automatic Fire Detection and Fire Alarm Systems Seminar
http://www.afaa.org/afaa/PDF/Auto_Fire_Detection_OKC_August_2003
.pdf

------------------
September 9-11, 2003 Batavia, NY - Sponsored by NYBFA
------------------
Intermediate Fire Alarm Seminar
http://www.afaa.org/afaa/PDF/NYBFA_Sept03.pdf

------------------
September 15-18, 2003 Oakland, CA - Sponsored by CAFAA
------------------
Plan Review Seminar
Intermediate Fire Alarm Seminar
http://www.afaa.org/afaa/PDF/PR_INT_CAFAA_OAKLAND_SEPT2003.PDF

------------------
September 22-25, 2003 Lafayette, LA - Sponsored by LA AFAA
------------------
Intermediate Fire Alarm Seminar
http://www.afaa.org/afaa/PDF/INT_TI_LAAFAA_Lafayette_Sept2003.pdf

------------------
September 16-18, 2003 Philadelphia, PA - Co-sponsored by PA AFAA
------------------
Intermediate Fire Alarm Seminar
http://www.afaa.org/afaa/PDF/IntFA_Philadelphia_Sept2003.pdf

------------------
October 8-9, 2003 Wichita, KS - Sponsored by KS AFAA
------------------
Plans Review Seminar.
Fire Alarm System Testing and Inspections Seminar.
More information will be available soon.

------------------
October 15-17, 2003 Boston, MA - Sponsored by New England AFAA
------------------
Intermediate Fire Alarm Seminar
More information will be available soon.

------------------
October 21-23, 2003 Anchorage, AK
------------------
Advanced Fire Alarm Seminar
http://www.afaa.org/afaa/PDF/IntFA_Anchorage_Oct2003.pdf

------------------
November 3-6, 2003 Anaheim, CA - Sponsored by CAFAA
------------------
Plan Review Seminar
Advanced Fire Alarm Seminar
More information will be available soon.

------------------
November 4-7, 2003 Boston, MA - Sponsored by New England AFAA
------------------
Advanced Fire Alarm Seminar
More information will be available soon.

------------------
November 21, 2003 Reno, NV
------------------
Plan Review Seminar
More information will be available soon.

------------------
December 2-4, 2003 Phoenix, AZ - Co-sponsored by AZ AFAA
------------------
Advanced Fire Alarm Seminar
More information will be available soon.

------------------
December 9-11, 2003 San Antonio, TX - Co-sponsored by TX AFAA
------------------
Advanced Fire Alarm Seminar
More information will be available soon.

================================================================
COMMENTS AND ACKNOWLEDGEMENTS
================================================================

Engineering Technician info: http://www.bls.gov/oco/ocos112.htm

ET News is published weekly and if possible, delivered on Sunday

ET News php/MySQL site by: Doug Hockinson http://metrodenver.org

The NICET acronym found herein refers to http://www.nicet.org
NATIONAL INSTITUTE FOR CERTIFICATION IN ENGINEERING TECHNOLOGIES

The AFAA acronym found herein refers to http://www.afaa.org
AUTOMATIC FIRE ALARM ASSOCIATION "AFAA is celebrating 50 years!"
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reprinted with permission from one or more of the following;
NFPA 70 National Electrical Code(r), NFPA 72 National Fire Alarm
Code(r), and NFPA 101(r) Life Safety Code(r), Copyright(c) NFPA,
Quincy, MA 02269. 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.
================================================================
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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.