Indian
Standard
SPECIFICATION FOR HEAT SENSITIVE FIRE DETECTORS FOR USE IN AUTOMATIC FIRE ALARM SYSTEM
SPECIFICATION FOR HEAT SENSITIVE FIRE DETECTORS FOR USE IN AUTOMATIC FIRE ALARM SYSTEM
IS : 2175-1988
(Reaffirmed 2000)
REAFFIRMED 2010
1. SCOPE
1.1
This standard
covers the general requirements, test methods and performance requirements for
heat sensitive (point) detectors for use in automatic fire alarm system.
2. TERMINOLOGY
2.0
For the
purpose of this standard, the following definitions shall apply.
2.1
Control and
Indicating Equipments—Unit(s) containing the controls, relays, switches and associated
circuits necessary to:
- provide power,
- receive signals from alarm indicating
(activation devices) and transmit them to the fire alarm devices and
control for automatic fire protection equipment, and
- electrically supervise the system
circuitry.
2.2
Detachable
Detector—A detector designed to be easily removed from its normal
operating position for maintenance and servicing purposes.
2.3
Fixed
Temperature Heat Sensitive Detector—A detector designed to operate when
the temperature of detector exceeds a predetermined value.
2.4
Line Detector—A linear form
of detector in which the detection process may take place anywhere along its
length.
2.5
Non-Detachable
Detector—A detector not designed to be easily removed from its normal
operating position for maintenance and servicing purposes.
2.6
Non-Resettable
(Non-Restorable) Detector—A detector which after response requires the
renewal of component or components to restore it to its normal state of
readiness to detect.
2.7
Point (Spot)
Type Detector—A detector in which the sensing element is essentially of a
compact area.
2.8
Rate of
Temperature Rise-cum-Fixed Temperature Heat Sensitive Detector—A detector
designed to operate within a given time:
- when the rate of temperature rise at
the detector exceeds a predetermined value regardless of the actual
temperature, and
- when the temperature at the detector
exceeds a predetermined value.
2.9
Resettable
(Restorable) Detector—A detector which after response and on cessation of the
conditions that caused the response, may be restored from its alarm state to
its normal state of readiness to detect without the renewal of any components.
3. TYPES AND GRADES
3.1
Heat sensitive
detectors (both resettable and non-resettable) covered in this standard are of
the following types:
- Fixed temperature detector, and
- Rate of temperature rise-cum-fixed
temperature detector.
3.1.1
Each of the
above detectors are subdivided into three grades based on the response time (see 5.2) as Grades 1, 2 and 3.
4. GENERAL REQUIREMENTS
4.1
The detector
shall be provided with means for mounting (on ceiling/wall) securely and
independent of any support from the attached wiring. The heat sensitive
element(s) shall not be closer than 15 mm of the detector.
4.2
Plastic, if
used, shall not start softening, deforming or melting at a temperature lower
than 95°C
5. PERFORMANCE TEST AND CRITERIA
FOR CONFORMITY
5.1
A sample of
required number of detectors (see Tables 1 and 2) of each design selected randomly
from production of not less than 200 detectors, shall be used for testing and
shall be numbered. The test (one or more) shall be carried out in the order
given in test schedule by the methods mentioned in Tables 1 and 2 and shall
conform to the requirements given in 5.2 to 5.9. The detectors shall pass all the tests. All the
tests are type tests which cover the production up to 10 000 numbers.
5.2
Directional
Dependence and Response Time—Detector number mentioned in Table 1
or 2 (as applicable) shall be tested for these properties according to the
method given in Appendix A and shall conform to the response time requirements
for the three grades as given in Table 3 and in 5.2.1 (as
applicable) in all orientations.
5.2.1
In case of
‘rate of temperature rise-cum-fixed temperature’ type detectors, the following
requirement shall also apply additionally.
5.2.1.1
At rates of
rise of air temperature less than l°C/min, the detector when tested according
to the method given in Appendix A, shall be required to operate at an air
temperature of not less than 58°C, and for Grades 1, 2 and 3 at not more than
65, 73 and 81°C, respectively.
5.3
Vibration—The detectors
(see Table 1 or 2
as applicable for numbering and rate of temperature rise) shall be tested in
the manner described in Appendix B and shall comply with its requirements.
5.4
Corrosion—The detectors
(see Table 1 or 2
as applicable for numbering and rate of temperature rise) shall be tested in
the manner described in Appendix C. They shall be deemed to comply with the
test if:
- For Four Days Corrosion—The response time of each detector
remains within the
TABLE 1 TESTING
SCHEME FOR RESETTABLE DETECTORS
(Clauses 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9, 5.10, 5.11, A-3.1, B-1.1 and D-1.1) |
|||||||||||||||||||
Test Procedure
|
Detector Number
|
Rate of Rise
(°C/min)
|
Remarks
|
||||||||||||||||
Clause
|
Test
|
1
|
2
|
3
|
4
|
5
|
6
|
7
|
8
|
9
|
10
|
1
|
3
|
5
|
10
|
20
|
30
|
0.2
|
|
5.2,
A-2
|
Directional
dependence
|
1
|
x
|
8
orientations Two tests at each rate : one with most favourable orientation,
other with least favourable orientation. With least favourable orientation
|
|||||||||||||||
5.2,
A-3
|
Time
of response
|
1
|
2
|
x
x |
x
x |
x
x |
x
|
x
x |
x
x |
0*
0* |
|||||||||
5.2.
A-3
|
Response
before test
|
3
|
4
|
5
|
6
|
7
|
8
|
9
|
10
|
x
|
x
|
||||||||
5.3
|
Vibration
|
3
|
4
|
||||||||||||||||
5.4
|
Corrosion,
4 days
Corrosion, 16 days Corrosion, Salt spray |
4
|
7
|
8
|
9
|
10
|
|||||||||||||
5.5
|
Shock
|
5
|
6
|
||||||||||||||||
5.6
|
Low
temperature
|
1
|
2
|
x
|
|||||||||||||||
5.7
|
High
temperature
|
2
|
x
|
x
|
|||||||||||||||
5.8
|
Supply
voltage variation
|
2
|
|||||||||||||||||
5.9
|
Insulation
resistance
|
1
|
Tests
at both rates at upper and lower limits of supply voltage Measurement of
resistance only With least
favourable orientation
|
||||||||||||||||
5.10
|
Humidity
|
1
|
|||||||||||||||||
5.11
|
Ageing
(applicable to fusible link type only) |
1
|
x
|
||||||||||||||||
A-3
|
Response
after test
|
1
|
3
|
5
|
7
|
8
|
9
|
10
|
x
|
||||||||||
2
|
4
|
6
|
8
|
10
|
|||||||||||||||
*Only
for dercctors subject to testing under 5.2.1 and 5.2.2.
|
|||||||||||||||||||
TABLE 2 TESTING
SCHEME FOR NON-RESETTABLE DETECTORS
(Each detector or element for one of the test only) (Clauses 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9, 5.10, 5.11, A-3.1, B-1.1 and D-1.1) |
||||||||||
Test Procedure
|
Element or
Detectors
Number |
Rate of Rise
(°C/Min)
|
Remarks
|
|||||||
Clause
|
Test
|
1 to 8
|
1
|
3
|
5
|
10
|
20
|
30
|
<0.2
|
|
5.2,
A-2
|
Directional
dependence
|
1 to 8
|
x
|
8
orientations
|
||||||
5.2,
A-3
|
Time of
response
|
9 to 22
23 to 36 |
x
x |
x
x |
x
x |
x
x |
x
x |
x
x |
0*
0* |
Two
tests at each rate : one with
most favourable orientation, other with least favourable orientation |
5.3
|
Vibration
|
37 to 38
|
||||||||
5.4
|
Corrosion,
4 days
Corrosion, 16 days Corrosion, Salt spray |
39 to 40
41 to 42 38 |
||||||||
5.5
|
Shock
|
43 to 44
|
||||||||
5.6
|
Low
temperature
|
45 to 46
|
||||||||
5.7
|
High
temperature
|
47
|
x
|
|||||||
5.8
|
Supply
voltage variation
|
48 to 51
|
x
|
x
|
||||||
5.9
|
Insulation
resistance
|
52
|
Measurement
of resistance only
|
|||||||
5.10
|
Humidity
|
53
|
x
|
|||||||
5.11
|
Ageing
(applicable to
fusible link detectors only) |
54
|
x
|
|||||||
A-3
|
Response
after test
|
37, 39, 41, 43, 45
38, 40, 42, 44, 46 |
x
x |
With
least favourable orientation
|
||||||
*Only
for detectors subject to testing under 5.2.1 and 5.2.2.
|
||||||||||
TABLE 3 ACCEPTANCE
LIMITS FOR RESPONSE TIME
(Clause 5.2) |
|||||||||
Rate of Rise of
Air Temperature
|
Lower Limit of
Response Time for All Response Grades
|
Upper Limit of
Response Time for
|
|||||||
Response Grade 1
|
Response Grade 2
|
Response Grade 3
|
|||||||
D°C/min
|
min
|
s
|
min
|
s
|
min
|
s
|
min
|
s
|
|
(1)
|
(2)
|
(3)
|
(4)
|
(5)
|
(6)
|
(7)
|
(8)
|
(9)
|
|
1
|
30
|
0
|
37
|
20
|
45
|
40
|
54
|
0
|
|
3
|
08
|
13
|
12
|
40
|
15
|
40
|
18
|
40
|
|
5
|
04
|
09
|
7
|
44
|
9
|
40
|
11
|
36
|
|
10
|
30
|
4
|
02
|
5
|
10
|
6
|
18
|
||
20
|
22-5
|
2
|
11
|
2
|
55
|
3
|
37
|
||
30
|
15
|
1
|
34
|
2
|
8
|
2
|
42
|
||
d. limits of its grade with an additional tolerance of ± 15 percent
or 10 whichever is greater.
- For Sixteen Days Corrosion—(Sulphur dioxide and salt spray)
- Each detector gives an immediate
continuous fault signal on connection to its C & I equipment, or
- Each detector gives an alarm signal
in time which does not exceed the upper limits of response grade 3.
5.5
Shock—The detector
(see Table 1 and 2,
as applicable for number and rate of temperature rise) shall be tested in the
manner described in Appendix D. They shall be deemed to comply with the test
if:
- no alarm is given when they are
subjected to the specified shock; and
- any change in response time of the
detectors after the test when compared with the response time obtained
before the test does not exceed 15 percent or 10 s, whichever is greater.
5.6
Low
Temperature—Response time of detectors (see Table 1 or 2, as applicable for numbering) shall
be put inside a suitable chamber/tunnel/enclosure and connected to its control
and indicating equipment. Air temperature in the chamber shall then be reduced
to a minimum of 0 ± 1°C at a rate not exceeding l°C/min. The detector shall be
kept in the condition of minimum temperature for 1 h to allow its temperature
to stabilize. After 1 h stabilization, the detector shall be taken out and kept
at a temperature of 27 ± 3°C for 5 to 6 h and then response times measured (see Appendix A), one at 3°C/min rate of temperature
rise and the other at 20°C/min rate of temperature rise using least favourable
orientation. Detectors shall be deemed to comply with this test if:
- no alarm is initiated during the test,
and
- any change in response time of the
detectors measured after the test when compared with the response time
obtained before the test does not exceed 15 percent or 10 s, whichever is
greater.
5.7
High
Temperature—The detector (see Table 1 or 2,
as applicable for numbering/rate of temperature rise) shall be mounted in the
tunnel in its normal operating condition with its normal fastenings. Keeping
the detector energized and disconnected from control and indicating equipment,
temperature of air flow in the tunnel shall be raised to 50°C at a rate not
exceeding 1°C/min. The temperature at this level shall be maintained for 1 h.
The detector shall then be energized and the response time shall be measured (see Appendix A) at 5°C/min rate of temperature rise
using the least favourable orientation. The detector shall respond within a
time not exceeding 11 min and 36 s for Grade 3, 9 min and 40 s for Grade 2, and
7 min and 44 s for Grade 1.
5.8
Supply Voltage
Variation—The detector (see Table 1 or 2,
as applicable for numbering/rate of temperature rise) shall be tested and
response times measured as described in Appendix E. They shall be deemed to
comply with this test if, as a result of supply variation, when compared with
the response time obtained before and after the test does not exceed 15 percent
or 10 s, whichever is greater and shall not give false alarm during the test.
5.9
Insulation
Resistance—The detector (see Table 1 or 2,
as applicable) shall be mounted in its normal operating condition with its
normal area fastening on a metal plate of at least 2 mm thickness and having
surface area at least 5 times the mounting surface of the detector. With the
plate shorted to ground terminal of the voltage source, voltage shall be
applied between the plate and the terminals of the detector which are
inter-connected. In 5 s, voltage shall be applied to a maximum of 500± 10 volts
DC. The maximum voltage shall remain applied for one minute. Insulation
resistance shall then be determined. Thereafter, it shall be subjected to a
temperature of 43 ± 2°C and relative humidity of 90 ± 3 percent for 10 days.
After conditioning, the detector shall be kept at room condition for one hour.
The insulation resistance shall be measured again. The detector shall be deemed
to comply with the test if the resistance in first measurement before the
exposure is not less than 10 M? and in second measurement after the exposure is
not less than 1 MΩ, and the detector shall not give a false alarm during the
test.
5.10
Humidity—The detector
(see Table 1 or 2,
as applicable) shall be kept inside a suitable humidity climatic chamber and
connected to its control and indicating equipment. Following climatic
conditions shall be created inside the test chambers:
Temperature
|
:
|
30 ± 2°C
|
RH
|
:
|
80 ± 5 percent
|
Duration of exposure
|
:
|
7 days
|
The detector
shall be transferred to tunnel within 1 hour of removal from the chamber and
its response time measured according to Appendix A. The time measured after the
exposure and before shall not differ by a factor greater than 16 and the
detector shall not give false alarm during the test.
5.11
Ageing
(Applicable to Fusible Alloy Link Type)—The detector (see Table 1 or 2, as applicable) shall be placed in a
suitable temperature oven and exposed for a period of 90 days to an ambient air
temperature which is 15°C below the rated operating temperature of the detector
but not less than 50°C. Following the exposure, the detector shall be allowed to
cool for not less than 5 hours. After cooling, the detector operating
temperature shall be ascertained according to Appendix A. The detector shall
operate within a temperature rangeT ± (0.035 T + 062) °C.
Note—T°C is rated operating temperature.
6. INFORMATION
6.1
Sufficient
information shall be given with the detectors to facilitate their correct
application. Such information shall include broad details of general and
technical features of the detector, correct monitoring position, reference to owners
manual, operation of test feature (if provided), maintenance instructions,
required electrical interface with the control and indicating equipment which
may take the form either of the values of current, voltage, etc, and their
allowable tolerances or a restriction of the detector to be used only in
conjunction with specified control and indicating equipment, etc.
7. MARKING
7.1
Each detector
shall be legibly and indelibly marked with the following:
- Manufacturers name or trade-mark;
- Type and description of detector and
number;
- Year of manufacture;
- Grading of detector which shall be
clearly indicated either by the colours as mentioned below, or by other
suitable means;
- Grade 1 : green
- Grade 2 : yellow
- Grade 3 : red; and
- Whether provided with fusible link.
7.2
Each detector
may also be marked with the Standard Mark.
Note—The use of the Standard Mark is governed by the provisions of the
Bureau of Indian Standards Act 1986 and the Rules and Regulations made
thereunder. The Standard Mark on products covered by an Indian Standard conveys
the assurance that they have been produced to comply with the requirements of
that standard under a well defined system of inspection, testing and quality
control which is devised and supervised by BIS and operated by the producer.
Standard marked products are also continuously checked by BIS for conformity to
that standard as a further safeguard. Details of conditions under which a
licence for the use of the Standard Mark may be granted to manufacturers or
producers may be obtained from the Bureau of Indian Standards.
APPENDIX A
METHOD OF TEST FOR TIME OF RESPONSE AND DIRECTIONAL DEPENDENCE (Clauses 5.2, 5.2. 1.1, 5.6, 5.7, 5.10, 5.11
and Tables 1 and 2)
A-1. APPARATUS
A-1.1
The response
time and directional dependence shall be measured in a wind tunnel specified in
Fig. 6 of IS : 9972–1981*. The air velocity in the tunnel shall be 0.8 ± 0.1
m/s and the air temperature shall be 28°C.
*Specification
for automatic sprinkler heads.
A-1.2
The detector
shall be mounted in its normal operating position on a board forming part of
the ceiling of the working section of the tunnel so that it is symmetrically
disposed with respect to the side walls of the tunnel, possibly in least
favourable mounting position. The air temperature shall be measured by suitable
thermocouple (copper-constantan wire not exceeding 025 mm in diameter, junction
consisting of a half twist with tightly tinned joint). The temperature
measuring device shall be approximate, at the same distance from the ceiling of
the wind tunnel as the sensitive element of the detector and approximately 230
mm from the sensitive element against the flow of air in a horizontal
direction. Before the test, the temperature of the air stream and the detector
shall stabilized at 28°C. The temperature control of the tunnel shall be such
that the temperature may be varied at 1, 3, 5, 10, 20 and 30°C/min with air
temperature within the tunnel being at all times within ± 3°C of that required
by the set rate of change of temperature, and also such that the temperature
can be raised from 52°C at a rate not exceeding 0.2°C/min to a temperature of
83°C.
A-2. DETERMINATION OF
DIRECTIONAL DEPENDENCE
A-2.1
The
detector(s) shall be connected to its control and indicating equipment and
tested in an air stream having a constant mass flow, equivalent to a velocity
of 08 ± 0.1 m/s at 28°C and with a uniform rate of rise of air temperature of
10°C/min. Eight such tests shall be made, the detector being rotated about a
vertical axis by 45° between successive tests so that the tests are made with
eight different orientations.
A-2.2
The least
favourable and most favourable orientations giving the greatest and the least
time delays, respectively, between the initiation of the temperature rise and
the operation of the detector shall be recorded.
A-3. TIME OF RESPONSE
MEASUREMENT
A-3.1
The detectors,
the response times of which are to be measured as mentioned in Tables 1 and 2,
shall be connected to the indicating equipment and shall be tested in an air
stream having a constant mass flow equivalent to a velocity of 0.8 ± 0.1 m/s at
28°C and having uniform rates of rise of air temperature 1, 3, 5, 10, 20 and
30°C/min (as applicable). The scheme of tests for various detectors is given in
Tables 1 and 2. The time interval between the initiation of temperature rise
and the operation of detector shall be recorded to an accuracy of 0.5 s and
shall be designated as the time of response.
A-4. FIXED
TEMPERATURE OPERATION
A-4.1
Two detectors
shall be tested as in A-3 with a rate of rise of air temperature not
exceeding l°C/min until the air temperature reaches 50°C and thereafter with a
rate of rise of air temperature not exceeding 0.2°C/min. One of the detectors
shall be in less favourable and the other in most favourable orientation. The
air temperature at the operation of the detectors shall be recorded.
APPENDIX B
VIBRATION TEST (Clause 5.3
and Tables 1 and 2)
B-1. PROCEDURE
B-1.1
The detector (see Table 1 or 2, as applicable for numbering/rate of
temperature rise), connected to its indicating equipment, shall be mounted in
its correct operating position and response time (see Appendix A) shall be noted and then the detector
shall be put on a vibration table. The test shall then be subjected to a
vertical vibration of amplitude 0.1 mm for a period of 5 minutes at each of the
following frequencies:
10, 15, 20,
25, 30, 35, 40, 45, and 50 c/s.
B-1.2
The operation
of the detector or resonance of any component shall be noted. If resonance
occurs, the detector shall be vibrated at the resonant frequency for a period
of one hour. If no resonance occurs, the detector shall be vibrated at 50 c/s
for one hour.
B-1.3
No fault or
alarm warning shall be indicated and no mechanical defect (including the
breakage/displacement of sensitivity seal, if provided) shall be visible during
or after the tests as in B-1.1 and B-1.2. The time of
response of two detectors shall be determined after the test. The change in
response, before and after the test shall not exceed 15 percent or 10 s,
whichever is greater.
APPENDIX C
CORROSION TEST (Clause 5.4
and Tables 1 and 2)
C-1. PROCEDURE
C-1.1
At least 15 cm
of connection wires/cables prescribed by the manufacturer shall be connected to
each detector or socket. When specific types of wires/cables are not prescribed
for connection, a 138 mm diameter (or nearest equivalent) single copper wire,
untinned, shall be used for connection leads in this test. The lowest point of
the detector shall be between 25 and 50 mm above the liquid surface. A guard
shall be provided to prevent drops of liquid from falling into the upper
surface of the detector.
C-1.2
The detector (see Table 1 or 2 as applicable for numbering) shall be
subjected to a corrosion atmosphere of Sulphur dioxide saturated with water vapor
and maintained at temperature of 45 ± 3°C. The apparatus shall consist of a 5
litre glass beaker fitted with a cover, an electric heater, and a thermostat
which can be set at 45 ± 3°C and copper tubing for flow of cool water round the
beaker.
The thermostat
shall be placed 140 mm above the bottom of the beaker. A hole is to be provided
in the lid for the insertion of the thermometer. The corrosion atmosphere shall
be produced by placing in beaker, a solution containing 20 g of sodium
thiosulphate (Na2S2O8.5H2O) in 500
ml of water. The detector shall then be suspended in beaker and 10 ml of acid
consisting of 156 ml of normal sulphuric acid (H2SO4) per
litre of aqueous solution shall be added twice daily. During the test, the
temperature near the detector shall be maintained at 45 ± 3°C by the heater and
the thermostat and water flow in cooling coil shall be so regulated that the
temperature at the outlet does not exceed 30°C. Where a test is intended to
last for more than 8 days, the detector shall be removed after 8 days and the
beaker emptied and cleared. A further 20 g of sodium thiosulphate in 500 ml of
water shall be put in the beaker, the detector replaced and the corrosive
atmosphere produced and maintained as before for a period of 8 days again.
C-1.2.1
The first pair
of detectors shall be mounted in the beaker and exposed to corrosive atmosphere
for a period of four days. Sixteen days exposure shall be given to the third
detector. After prescribed exposures, the detectors shall be removed and
allowed to dry for seven days, in normal room environment without disturbing
the connections and the response time of detectors shall be measured as in
Appendix A.
C-1.3
Salt Droplet
Test—This test shall be conducted on the fourth detector. The detector
shall be suspended with its lower edge 5 to 75 cm above the surface of water in
a large dish and the whole shall be enclosed by a box-like cover. Once daily
for a total period of 16 days the detector shall be removed, sprayed over its
whole surface by a spray of sea water of the following composition and replaced
under this cover;
Sodium chloride, g/l
|
23
|
Sodium sulphate, g/l
|
8.9
|
Magnesium chloride, g/l
|
9.8
|
Calcium chloride, g/l
|
1.2
|
The
temperature throughout the test shall be maintained at 27 ± 2°C. After 16 days,
the detector shall be removed and allowed to dry. It shall then be connected to
its normal indicating equipment using the corroded lead and the response time
shall be measured as in Appendix A.
APPENDIX D
SHOCK TEST (Clause 5.5)
D-1. PROCEDURE
D-1.1
The response
time of the detector (see Table 1 or 2,
as applicable for numbering/rate of temperature rise for test) shall be
determined. A detector incorporating electrical contacts shall be mounted on a
piece of 10 × 5 cm hardwood resting on edge on solid supports spaced 1 m apart.
The test shall be made with the detector in the following two positions:
- At the midpoint on the horizontal
under side, and
- At the midpoint on the vertical side.
D-1.2
A metal block
of 35 kg mass shall be dropped on to the midpoint of the 10 x 5 cm timber
from a height of 30 cm above the top horizontal surface of the timber. The
detector shall be connected in circuit corresponding to its normal operation
during the test and shall not operate as a result of shock.
D-1.3
After the
test, the time of response of the detectors shall be determined (see Appendix A) :
APPENDIX E
SUPPLY VOLTAGE VARIATION TEST (Clause 5.8)
E-1. PROCEDURE
E-1.1
When upper and
lower limits of supply voltage are prescribed, detector(s) shall be tested at
both the limits. At upper limit, two tests shall be carried out and similarly
two tests shall be conducted at the lower limit. When one nominal value of supply
voltage is prescribed, two tests shall be carried out with voltage to control
and indicating equipment reduced as 85 percent of nominal value (to be treated
to lower limit) and further two tests with voltage increased to 110 percent of
the nominal value and the response time measured (see Appendix A). In each pair of tests, one test shall
consist of the measurement of response time with a rate of rise of 3°C/min and
the other with a rate of rise of 20°C/min. The response times shall be
recorded. For resettable detectors, the same detector shall be used for all the
tests of E-1.1. For non-resettable detectors, a separate detector or
detector element shall be used for each of the tests of E-1.1.
NFPA 72 - Heat Detection
Heat detectors work by detecting a temperature change or a
high temperature limit. There are several types of heat detectors, including
fixed-temperature, elevation rate, and combination detectors that use both
types of sensing.
👉🏻Fixed-temperature heat
detectors operate by activating an alarm when a predetermined temperature limit
is reached. For example, a heat detector can be configured to trigger an alarm
when the temperature in a room reaches 57 °C (135 °F).
👉🏻Rate of increase heat
detectors operate by detecting rapid temperature increases. These detectors
will activate an alarm if the temperature rises too quickly, even if the
temperature does not reach a predetermined limit. For example, a rate of
increase detector can be activated if the temperature in a room rises by 15 °F
(8 °C) in a minute.
👉🏻Combined heat detectors use
fixed temperature and rate of rise sensors to provide more comprehensive fire
detection. These detectors are often used in areas where fires can develop
rapidly, such as kitchens and boiler rooms.
Heat detectors use different technologies to detect
temperature, including thermocouples, thermistors, and infrared sensors.
👉🏻Thermocouples and thermistors
work by measuring changes in electrical resistance that occur as the temperature
changes. Infrared sensors detect changes in infrared radiation emitted by
objects as they heat.
Once a heat detector detects a temperature change or a high
temperature threshold, it will activate an alarm or alert system, such as a
strobe light or voice alarm, to alert occupants of the potential fire risk.