GB 20517-2025Self-contained smoke alarms using scattered light or transmitted light (English PDF)

3 Terms and definitions

3.1 m value: smoke concentration measured by the optical method. Note: see A.2 of Annex A.

3.2 y value: smoke concentration measured by the ionization method. Note: see A.3 of Annex A.

3.3 Fire alarm status: the working state of a self-contained smoke fire detection alarm when it is emitting a fire alarm signal.

3.4 Normal monitoring status: the normal working state of a self-contained smoke fire detection alarm in which it is emitting neither a fire alarm signal nor a fault signal.

3.5 Average current: the average value of the supply current of a self-contained smoke fire detection alarm in the normal monitoring status.

4 Classification

4.1 By working mode, alarms are divided into single-point alarms and interconnected alarms.

4.2 By response threshold, alarms are divided into type A, with an adjustable response threshold, and type B, with a fixed response threshold.

4.3 By transmission mode, alarms are divided into those having a wireless communication function and those having none.

5.2 Appearance requirements

The surface of the alarm shall be free of corrosion, of peeling or blistering of the coating, and of obvious mechanical damage such as scratches, cracks or burrs; fastened parts shall not be loose.

The surface of the alarm shall carry the product marking and a quality inspection conformity marking.

The alarm shall have complete factory packaging, and the packaging shall contain an instruction manual in Chinese.

5.3 Performance of the main parts and components

5.3.1 Power supply mode. The alarm shall be powered by an internal battery only.

5.3.2 Detection principle. The alarm shall detect smoke on the scattered-light or transmitted-light principle; detection by the radioactive-source ionization principle shall not be used.

5.3.3 Indicator lamps. A red alarm confirmation lamp is required, which lights when the smoke parameter of the monitored area meets the alarm condition. A yellow sensing-element contamination lamp is also required, which lights when contamination of the sensing element affects normal use of the alarm and stays lit until the contamination is removed. Where the alarm confirmation lamp is used to indicate other working states of the alarm, those states shall be clearly distinguishable from the fire alarm status. When lit, an indicator lamp shall be clearly visible 6 m directly in front of it under an illuminance not exceeding 500 lx.

5.3.4 Protection against ingress of foreign bodies. The alarm shall be able to prevent a spherical body of (1.3 +/- 0.05) mm diameter from entering the detection chamber.

5.3.5 Switches, keys and buttons. Keys and buttons shall operate flexibly and reliably and their function shall be marked in Chinese, the marking being clear and durable. The surface of the alarm shall carry a self-test key and a silence key.

5.3.6 Connection of external equipment. Where the alarm has a function for connecting external equipment such as a remote monitor, a control relay, a wireless communication device, a transceiver unit or a field-end platform, an open circuit or a short circuit in the line to that equipment shall not affect the normal operation of the alarm.

5.3.7 Structural elements. Apart from the battery, the base and the subscriber identity module, the alarm shall have no components that the user can remove or repair. A clear warning shall be given when the battery is taken out; where the battery is connected by a plug-in connector, a clear warning shall be given when the plug is not connected.

5.3.8 Factory settings. The factory settings of the alarm shall not be capable of being changed except by a special means, such as a dedicated tool or a password, or by breaking a seal.

5.3.9 Instruction manual. The alarm shall have an instruction manual in Chinese whose content meets GB/T 9969.

5.3.10 Transceiver unit. A transceiver unit mated with the alarm shall meet Annex B.

5.4 Functions

5.4.1 Fire alarm function. When the smoke parameter of the monitored area reaches the preset value, the alarm shall emit an audible and visible fire alarm signal, clearly distinguishable from other audible and visible signals. Where the alarm has a fire alarm signal output function, the manufacturer shall state the type and parameters of the output signal in the instruction manual. An alarm with a wireless communication function shall meet 5.4.1 and 5.6 of GB/T 45839-2025.

5.4.2 Silencing function. The alarm shall provide silencing both by wireless remote control and by key. Where infrared remote control is used, the alarm shall be able to accept the wireless infrared signal of a household appliance remote control as the silencing trigger signal. The alarm shall not be silenced within 60 s after it has emitted the audible and visible fire alarm signal. The silencing period shall be not less than 5 min and not more than 15 min; during that period the alarm shall emit neither the audible fire alarm signal nor the audible fault warning signal. After the silencing period ends, the alarm shall emit the audible and visible fire alarm signal again if the smoke parameter of the monitored area still meets the fire alarm condition.

5.4.3 Self-test function. The alarm shall have a self-test function. When the self-test is performed, the alarm shall be able to check the operation of its audible device and its indicator lamps, but shall not output a fire alarm trigger signal, and the external auxiliary equipment connected to it shall not operate.

5.4.4 Data recording and export function. Where the alarm has a data recording function, it shall be able to record not less than 20 fire alarm records with the corresponding year, month, day, hour, minute and second; the time shall be correctable by setting, and the data shall be exportable.

5.5 Sound pressure level

Under the rated working voltage and under the threshold voltage at which the battery fault warning signal is emitted, when the smoke parameter of the monitored area meets the alarm condition the alarm shall emit an audible and visible fire alarm signal. The sound pressure level of the audible fire alarm signal is measured in a free sound field 3 m directly in front of the alarm. The initial sound pressure level shall be not greater than 45 dB (A-weighted), and during the period from 3 s to 10 s the sound pressure level shall rise progressively to between 80 dB and 105 dB (A-weighted).

5.6 Audible device. Under the rated voltage the alarm shall be able to complete at least 50 consecutive transitions of the working state from normal monitoring status to fire alarm status; after the transitions the alarm shall be able to emit the fire alarm signal continuously for 72 h, and after those 72 h the sound pressure level of the audible fire alarm signal shall still meet 5.5.

5.7 Measurement of the response threshold

5.7.1 The response threshold of the alarm is measured in the standard smoke chamber, which shall comply with Annex A and shall also meet the requirements of the orientation, air flow stability, dry heat (operational) and ambient light interference immunity tests.

5.7.2 The alarm is mounted in the smoke chamber in its normal monitoring position. Where the relevant clause gives no special requirement, the alarm is placed in its most unfavourable orientation, the air velocity around the alarm is (0.2 +/- 0.04) m/s and the air temperature is (23 +/- 5) °C.

5.7.3 The test smoke shall comply with Annex C.

5.7.4 Before the test, no test smoke shall be present in the smoke chamber or inside the alarm.

5.7.5 The test smoke is fed into the smoke chamber at a rate of rise of the smoke concentration between 0.015 dB per metre per minute and 0.1 dB per metre per minute. The calculation formula and the measurement method for the m value follow Annex A.

5.7.6 The response threshold of the alarm is the m value of the smoke concentration, in decibels per metre, at the moment the alarm emits the fire alarm signal.

5.8 Orientation, repeatability and consistency

5.8 Orientation. The alarm is rotated about its vertical axis by 45° in the same direction and the response threshold is measured eight times in all. The orientations giving the largest and the smallest response threshold are respectively the most unfavourable and the most favourable orientation, and the ratio of the largest response threshold to the smallest response threshold shall be not greater than 1.6.

5.9 Repeatability. Six smoke response thresholds are measured on the same alarm in the same orientation, and the ratio of the largest to the smallest response threshold shall be not greater than 1.6.

5.10 Consistency. The response thresholds of several alarms are measured in succession in the most unfavourable orientation, giving a smallest, a largest and an average response threshold. For a type A alarm with the response threshold set to the lowest threshold level, the smallest response threshold shall be not less than 0.05 dB/m; with the response threshold set to the highest threshold level, the smallest response threshold shall be not less than 0.3 dB/m. At each threshold level, the ratio of the largest response threshold to the average response threshold shall be not greater than 1.33 and the ratio of the average response threshold to the smallest response threshold shall be not greater than 1.5. For a type B alarm the smallest response threshold shall be not less than 0.15 dB/m, with the same two ratio limits of 1.33 and 1.5. The ratio evaluation is made on not less than 10 units; where fewer than 10 samples are available the ratios are not evaluated and only the response threshold requirement applies, the values serving as the response thresholds before the environmental tests.

5.11 Battery fault warning performance

5.11.1 The alarm shall have a battery voltage detection function. After the alarm is energized it shall first check the battery voltage, and the checking period shall be not greater than 24 h. Before the battery supply voltage falls below the level that keeps the alarm working normally, the alarm shall emit an audible battery fault warning signal clearly distinguishable from the audible fire alarm signal. An interconnected alarm shall have a battery fault warning signal output function, and the manufacturer shall state the type and parameters of the output signal in the instruction manual.

5.11.2 When the audible fault warning signal is being emitted because of a battery fault, the alarm shall be capable of being silenced for (7 +/- 1) h. During the silencing period the alarm shall still be able to emit the audible and visible fire alarm signal if the smoke parameter of the monitored area meets the fire alarm condition.

5.12 Function of interconnected alarms

Interconnected alarms shall be connected by wire and, at the maximum load connection, shall meet the following.

a) When one interconnected alarm emits a fire alarm signal, the other interconnected alarms connected with it shall emit the audible fire alarm signal within 1 min.

b) When an interconnected alarm that is within its silencing period receives a fire alarm signal from another interconnected alarm connected with it, all the alarms, including those within a silencing period, shall emit the audible fire alarm signal.

c) An open circuit or a short circuit in the interconnection line shall not affect the alarm function of that alarm.

d) The response threshold measured in the interconnected condition, compared with the response threshold of the same unit in the consistency test, shall give a ratio of the larger to the smaller value not greater than 1.6.

5.13 Reverse polarity performance and power supply performance

5.13 Reverse polarity performance. Where the structure of the alarm allows it, the battery is connected to the battery terminals with reversed polarity. Reversed polarity shall not damage the alarm. With the polarity reversed the alarm may emit a fault warning signal or a fire alarm signal; if it emits no signal within 15 s the reversed connection is held for 2 h. The battery is then refitted correctly and the response threshold measured; compared with the response threshold of the same unit in the consistency test, the ratio of the larger to the smaller value shall be not greater than 1.6. After the reversed connection, when supplied at the fault voltage the alarm shall emit a fault signal.

5.14 Power supply performance. For an alarm with a replaceable battery, the battery or battery pack is discharged continuously for 168 h at 150 times the average working current; for an alarm with a non-replaceable battery, continuously for 336 h at 250 times the average working current. After the discharge, the capacity of the battery or battery pack shall be such that the sound pressure level of the audible fire alarm signal measured 3 m directly in front of the alarm has an initial value not greater than 45 dB (A-weighted) and rises progressively during the period from 3 s to 10 s to between 80 dB and 105 dB (A-weighted). On further discharge, before the battery capacity can no longer keep the alarm working normally the alarm shall emit the battery fault warning signal, and shall emit that signal at least once a minute for 7 d. After 7 d of fault warning, the response threshold is measured and compared with the response threshold of the same unit in the consistency test, the ratio of the larger to the smaller value being not greater than 1.6, and the alarm shall still be able to emit the fire alarm signal continuously for at least 4 min.

5.15 Air flow stability and immunity to ambient light

5.15 Air flow stability. The arithmetic mean of the response thresholds in the most unfavourable and the most favourable orientation at an air velocity of (0.2 +/- 0.04) m/s is compared with the arithmetic mean of the response thresholds in the same two orientations at an air velocity of (1.0 +/- 0.2) m/s; the ratio of the larger mean to the smaller mean shall be not greater than 1.6.

5.16.1 With the alarm in its most unfavourable orientation and in the orientation rotated 90° about its vertical axis, it shall emit neither a fire alarm signal nor a fault warning signal under the following ambient light interference produced by the flashing light apparatus of Annex D: each lamp in turn switched on for 10 s and off for 10 s, ten times over; each opposed pair of lamps in turn switched on for 10 s and off for 10 s, ten times over; and all four lamps switched on together for 1 min.

5.16.2 In the same two orientations, the response threshold measured with the four lamps switched on together is compared with the response threshold of the same unit in the consistency test; the ratio of the larger to the smaller value shall be not greater than 1.6.

5.17 Climatic environment endurance

The alarm shall withstand the climatic environment tests set out in Table 1. During the tests the alarm shall emit neither a fire alarm signal nor a fault warning signal. After the tests the alarm shall show no destruction of the coating and no corrosion, shall be able to stay in the normal monitoring status, and its response threshold compared with the response threshold of the same unit in the consistency test shall give a ratio of the larger to the smaller value not greater than 1.6.

Table 1 sets four tests, each with its test parameters, test conditions and working state. The dry heat (operational) test is at (55 +/- 2) °C for 2 h. The cold (operational) test is at (-10 +/- 2) °C for 2 h. The cyclic damp heat (operational) test is at an upper temperature of (40 +/- 2) °C for 2 cycles. The sulfur dioxide (SO2) corrosion (endurance) test is at a sulfur dioxide concentration by volume of (25 +/- 5) parts per million, (25 +/- 2) °C and (75 +/- 5) % relative humidity for 21 d. All four tests are performed with the alarm in the normal monitoring status.

5.18 Mechanical environment endurance

The alarm shall withstand the mechanical environment tests set out in Table 2. During the tests the alarm shall emit neither a fire alarm signal nor a fault warning signal. After the tests the alarm shall show no mechanical damage and no loosening of fastened parts, shall be able to stay in the normal monitoring status, and its response threshold compared with the response threshold of the same unit in the consistency test shall give a ratio of the larger to the smaller value not greater than 1.6.

Table 2 sets three tests. The shock (operational) test uses a half-sine pulse of 6 ms duration with a peak acceleration obtained from the mass M of the test sample in kilograms, in one direction, with 3 shock pulses in that direction. The impact test uses an impact energy of (1.9 +/- 0.1) J and a hammer head speed of (1.5 +/- 0.125) m/s, with one impact in each direction. The vibration, sinusoidal (operational) test uses a frequency cycling range of 10 Hz to 150 Hz, an acceleration amplitude of 10 metres per second squared, a sweep rate of 1 octave per minute, one sweep cycle per axis and one axis. All three tests are performed with the alarm in the normal monitoring status.

5.19 Electromagnetic compatibility performance

The alarm shall withstand the electromagnetic interference tests set out in Table 3. During the tests the alarm shall emit neither a fire alarm signal nor a fault warning signal. After the tests the alarm shall be able to stay in the normal monitoring status, and its response threshold compared with the response threshold of the same unit in the consistency test shall give a ratio of the larger to the smaller value not greater than 1.6.

Table 3 sets three tests. The radiated radio-frequency electromagnetic field immunity test uses a field strength of 10 V/m over the frequency range 80 MHz to 1000 MHz, a frequency step not exceeding 1 % of the preceding frequency, and 80 % amplitude modulation with a 1 kHz sine wave. The test of immunity to conducted disturbances induced by radio-frequency fields uses the frequency range 0.15 MHz to 80 MHz, a level of 140 dB relative to one microvolt, and the same 80 % modulation with a 1 kHz sine wave; a footnote states that this test applies to interconnected alarms and to alarms having external connecting lines. The electrostatic discharge immunity test uses 8 kV air discharge for insulating enclosures and 6 kV contact discharge for conductive enclosures and coupling planes, both discharge polarities, a discharge interval not less than 1 s and 10 discharges per point. All three tests are performed with the alarm in the normal monitoring status.

5.20 Fire sensitivity and contamination of the sensing element

5.20 Fire sensitivity performance. The alarm is installed in the environment specified in Annex E and shall emit a fire alarm signal before the end of each of the test fires specified in Annex F to Annex I.

5.21 Contamination resistance of the sensing element. The alarm shall have a sensing-element contamination warning function; when the sensing element is contaminated and the contamination meets the contamination warning condition, the alarm shall emit a contamination fault signal.

6.1 General requirements for the tests

6.1.1 Test atmospheric conditions. Unless a relevant clause states otherwise, the tests are carried out at a temperature of 15 °C to 35 °C, a relative humidity of 25 % to 75 % and an atmospheric pressure of 86 kPa to 106 kPa.

6.1.2 Mounting. The alarm is mounted in the normal way specified by the manufacturer. Where the instruction manual gives several mounting arrangements, the one least favourable to the operation of the alarm is used in the tests.

6.1.3 Tolerances. Unless a relevant clause states otherwise, the tolerance on the test data is +/-5 %; the environmental condition parameters follow GB/T 16838.

6.1.4 Test samples. Before the tests the manufacturer supplies 20 samples of a single-point alarm, or, for an interconnected alarm, a number of samples equal to 19 plus the maximum connectable quantity declared by the manufacturer.

6.1.5 Test condition. Unless a relevant clause states otherwise, the sample is connected to the battery specified by the manufacturer, and the battery is fully charged.

6.1.6 Inspection of appearance and main parts. Before the other tests the samples are inspected against 5.2 and 5.3, and only samples meeting those requirements go on to the other tests.

6.1.7 Test programme. Type A samples follow the programme of Table 4; the consistency test is run separately at each response threshold level and the samples are numbered by their response threshold at the highest threshold level, the four samples with the largest response threshold being numbered 17 to 20 in order and the remaining samples numbered 1 to 16 at random. The fire sensitivity test is run at the highest response threshold level of the sample and the other tests at the lowest response threshold level. Type B samples also follow the programme of Table 4; after the consistency test the four samples with the largest response threshold are numbered 17 to 20 in order and the remaining samples numbered 1 to 16 at random. For interconnected alarms, 20 samples are picked at random and numbered as above and the remaining samples are numbered consecutively from 21.

6.25 Sensing element contamination alarm function test

6.25.1.1 The sample is mounted in the dust environment simulation test apparatus in accordance with Annex K and 6.1.2 and put into the normal monitoring status.

6.25.1.2 Before the test, the apparatus is adjusted so that the air velocity around the sample inside it is (0.4 +/- 0.1) m/s.

6.25.1.3 The dust specified in Annex K is fed into the apparatus so that the dust concentration inside it is (100 +/- 30) mg per cubic metre, or the concentration declared by the manufacturer but not more than (200 +/- 30) mg per cubic metre, and the simulated dust contamination environment is held for 1 h. The air flow and the dust feed are then stopped and the condition held for a further 1 h. The state of the sample is observed and recorded throughout.

6.25.1.4 If the sample emits a contamination fault signal during the test, the requirement is met and the test ends; the sample is allowed to emit a fire alarm signal during that time.

6.25.1.5 If the sample emits no contamination fault signal during the test, it is taken out afterwards. If it emits a contamination fault signal within 100 s, the requirement is met. If it still emits a fire alarm signal after 100 s, the requirement is not met. If after 100 s it emits neither a fire alarm signal nor a contamination fault signal, it is mounted in the smoke chamber in its most unfavourable orientation, put into the normal monitoring status and its response threshold measured in accordance with 5.7; compared with the response threshold of the same sample in the consistency test, the ratio of the larger to the smaller value shall be not greater than 1.6.

6.25.1.6 For a sample whose ratio in 6.25.1.5 is not greater than 1.6, the sensing element is contaminated by the simulated test means specified by the manufacturer until the contamination meets the contamination warning condition, and the sample shall then emit a contamination fault signal.

7 Inspection rules

7.1.1 Before the product leaves the factory the alarm is inspected for appearance and main parts and components, by the consistency test and by the cyclic damp heat (operational) test.

7.1.2 The manufacturer lays down the sampling method and the inspection and judgement rules for the factory inspection.

7.2.1 Type inspection covers all the applicable test items specified in the document, and the inspection samples are drawn from products that have passed the factory inspection.

7.2.2 Type inspection is carried out on trial production of a new product or on transfer of an existing product to another factory; after regular production has started, when the structure, the main parts or components or the production process have changed appreciably in a way that may affect product performance; when the technical requirements of the product standard change; when production has stopped for more than one year and is resumed; after rectification following a major quality accident; when the quality supervision authority requires it by law; when the compulsory market access system requires it; and in other situations where only type inspection can demonstrate the quality of the product.

7.2.3 The inspection results are judged by the type inspection judgement method of GB 12978.

8 Marking

8.1.1 The product marking shall be clearly visible while the alarm is being installed and maintained.

8.1.2 The product marking shall not be applied to screws or to other parts that are easily removed.

8.2.1 Every alarm shall carry, clearly marked, the product name and model; the number of the standard the product is made to; the name of the manufacturer and the name and address of the producing plant; the date of manufacture and the product serial number; and the main technical parameters of the product, namely the rated working voltage, the type, voltage and number of the batteries used, and the average working current.

8.2.2 Where the product marking uses uncommon symbols or abbreviations, they shall be explained in the instruction manual of the alarm.

8.3 Every alarm shall carry a quality inspection conformity marking.

A Annex A (normative) Threshold test smoke chamber

A.1 Test equipment. The arrangement of the measuring zone, the test instruments and the alarm is shown in Figure A.1 and Figure A.2. The measuring working zone shall be able to accommodate the dedicated flashing light apparatus used in the ambient light interference test and complying with Annex D. The distance from the edge of the alarm to the edge of the measuring platform shall be not less than 20 mm. The smoke chamber shall be able to keep the air velocity in the measuring working zone within the values the tests require, and shall be able to raise the temperature of the measuring working zone to (55 +/- 2) °C at a rate of rise not exceeding 1 °C/min.

A.2 Optical measurement of the response threshold. The response threshold of the alarm, that is the smoke concentration at the moment of alarm expressed as the light obscuration coefficient m in decibels per metre, is measured with an optical smoke density meter, which uses the exponential attenuation of the radiant power of a light beam acted on by smoke particles. In the formula for the light obscuration coefficient, m is the light obscuration coefficient in decibels per metre, d is the optical measuring path length of the test smoke in metres, and the two radiant powers are the power received without smoke and the power received with smoke, both in watts. The optical measuring path length shall be not greater than 1.1 m, the beam shall be mainly infrared light, and the reading of the measuring instrument shall be zeroed before each measurement.

A.3.1 Ionization measurement of the smoke concentration. The smoke concentration measured by the ionization method is expressed as the dimensionless y value and is measured with an ionization smoke concentration meter, which samples and measures continuously by drawing air through it. The meter consists of an ionization chamber, a current amplifier and a suction pump. Air containing smoke particles is drawn by the pump so that it diffuses into the measuring space of the ionization chamber, where it is ionized by alpha radiation; when a voltage is applied between the two electrodes an ionization current flows, and that current changes under the action of the smoke particles, the relative change in the ionization current serving as the measure of the smoke concentration. In the two relationships given for the y value, the two currents are the ionization current with clean air and the ionization current with smoke particles, both in picoamperes, d is the mean particle diameter of the smoke particles in metres, z is the number concentration of smoke particles per cubic metre, and the ionization chamber constant is expressed per square metre.

A.3.2 Structure. The mechanical structure of the ionization chamber is shown in Figure A.4 and the names, characteristics, materials and quantities of its parts are listed in Table A.1; the main dimensions are given with tolerances and the dimensions given without tolerances are recommended values.

A.3.3 Technical requirements. The radioactive source shall use the nuclide americium-241, with an activity of 120 kBq within +/-20 %, equal to 3.5 microcuries; the cut face of the source shall be tightly enclosed by the source holder and the surface of the source shall be protected by a noble metal layer; the source disc diameter is 27 mm. The working circuit of the ionization smoke concentration meter is shown in Figure A.5. The input resistance of the current amplifier shall meet the working requirement. The air flow rate of the suction pump is 30 L/min within +/-10 %.

B Annex B (normative) Performance requirements for the transceiver unit

B.1.1.1 The transceiver unit shall be able to receive the fire alarm signal of every alarm in the system, emit an audible and visible fire alarm signal within 10 s, indicate the location of the alarm and hold that indication until the transceiver unit is manually reset. The audible alarm signal shall be capable of being silenced manually and shall be capable of being started again when a further fire alarm signal comes in.

B.1.1.2 The transceiver unit shall be able to receive the battery fault warning signal of every alarm in the system and emit within 100 s an audible and visible fault signal clearly distinguishable from the audible and visible fire alarm signal, showing the location of the fault. The audible fault signal shall be capable of being silenced manually and of being started again when a further fault signal comes in; the visible fault signal shall be held until the fault is cleared or the unit is manually reset.

B.1.1.3 The transceiver unit shall have an independent automatic control output. It shall be possible to enter the starting logic by hand or by writing a program, and on receiving a fire alarm signal that satisfies the specified logic the transceiver unit shall operate the automatic control output within 3 s.

B.1.1.4 The transceiver unit shall have an independent manual control output and shall operate that output within 3 s of the manual control key being operated.

B.1.1.5 The transceiver unit shall meet the other requirements laid down by the manufacturer.

B.1.2 to B.1.4 Environmental and electromagnetic endurance. The transceiver unit shall withstand the climatic environment tests of 5.9 of GB 4717-2024, the mechanical environment tests of 5.10 of GB 4717-2024 and the electromagnetic compatibility tests of 5.8 of GB 4717-2024. During each of those tests the transceiver unit shall emit neither a fire alarm signal nor a battery fault warning signal and neither the automatic control output nor the manual control output shall operate; after the tests the unit shall be able to stay in the normal monitoring status and its functions shall still meet B.1.1, and after the climatic tests it shall also show no destruction of the coating and no corrosion, and after the mechanical tests no mechanical damage and no loosening of fastened parts.

B.1.5 to B.1.7 Electrical requirements. The insulation resistance of the transceiver unit shall meet 5.5 of GB 4717-2024, its electric strength shall meet 5.7 of GB 4717-2024, with the functions still meeting B.1.1 after the test, and its leakage current shall meet 5.6 of GB 4717-2024.

B.2.1 Function test. The transceiver unit is made up into a system with two alarms and energized into the normal monitoring status. One alarm is made to emit a fire alarm signal and the interval to the fire alarm signal of the transceiver unit is measured, the audible and visible indication being observed and recorded. The audible fire alarm signal is silenced by hand and the second alarm made to emit a fire alarm signal, so as to check the silencing function and the restart of the audible fire alarm signal. The automatic control output on fire alarm is checked and recorded, the unit is reset by hand and the indication observed and recorded. The same sequence is then run for the battery fault warning signal, and finally the manual control key is operated and the operation and operating time of the manual control output are checked and recorded.

C Annex C (normative) Test smoke, and Annex D flashing light apparatus

C.1 The particle size of the smoke particles in the test smoke shall lie between 0.5 µm and 1.0 µm, and the test smoke chosen shall be used throughout all the test items.

C.2 The test smoke shall be reproducible and stable as regards particle size distribution, particle size, particle structure and optical properties.

C.3 The stability of the test smoke is assured by monitoring the stability of the ratio of the m value to the y value.

Annex D. The test apparatus is a dedicated flashing light apparatus in the form of a regular hexahedron, shown in Figure D.1. The inner faces of the four closed sides are lined with polished aluminium foil. Four annular light-emitting diode lamps are fixed one to the inner face of each of those four sides, each lamp having a power of 20 W to 25 W, a colour temperature of 2700 K to 8000 K and a diameter of about 200 mm to 380 mm. The mounting position of the lamps shall not affect the measurement of the response threshold. The alarm is fitted at the centre of the top face of the hexahedron so that light can fall on it from above, from below and from both sides. The electrical wiring of the lamps shall not interfere with the alarm.

E Annex E (normative) Fire test room

E.1 The fire test room measures 9 m to 11 m long, 6 m to 8 m wide and 3.8 m to 4.2 m high. The ceiling is a horizontal plane made of heat-resistant, heat-insulating material. The room shall have ventilation equipment and shall meet the ambient conditions the fire tests require. Before the test fire is lit there shall be no air movement in the room.

E.2 Test arrangement. The fire source is placed at the centre of the floor, and the alarms and the measuring instruments are mounted on an arc of 3 m radius and 60° included angle centred on the centre of the ceiling, as shown in Figure E.1.

E.3 Measuring instruments. The optical smoke density meter shall comply with Annex A, the ionization smoke concentration meter shall comply with Annex A, and a temperature sensor is used.

F Annex F (normative) Test fire SH1 — smouldering pyrolysis wood fire

F.1 Fuel: ten beech wood sticks of 75 mm by 25 mm by 20 mm with a moisture content of about 5 %.

F.2 Arrangement: as shown in Figure F.1, the sticks are laid radially on a hot plate of 220 mm diameter with a rated heating power of 3 kW, the 20 mm side in contact with the plate surface. The plate surface has eight concentric grooves 5 mm wide and 2 mm deep, spaced 3 mm apart, the outermost groove being 4 mm from the edge of the plate. At the start of the test the plate is energized, and its temperature shall rise from room temperature to 600 °C within 11 min and stay steady there. The plate temperature is measured by a temperature sensor attached in good thermal contact to the fifth groove counting from the edge of the plate; the wood sticks shall not cover the temperature sensor.

F.3 End of test: the m value reaches 2 dB/m, or all the alarms have emitted a fire alarm signal.

F.4 Fire parameters: the relation between the m value and the y value and the relation between the m value and the test time shall lie within the shaded areas of Figure F.2 a) and Figure F.2 b), and no flame shall appear before the end of the test.

G Annex G (normative) Test fire SH2 — smouldering cotton rope fire

G.1 Fuel: clean, dry cotton rope.

G.2 Arrangement: 90 lengths of rope, each 80 cm long and weighing 3 g, are fixed to a metal ring of 10 cm diameter, which is then hung from a support 1 m above a non-combustible plane, as shown in Figure G.1.

G.3 Ignition: the ropes are lit at their lower ends and the flames extinguished immediately so that they go on smouldering. The test starts only when all the ropes have been lit.

G.4 End of test: the m value reaches 2 dB/m, or all the alarms have emitted a fire alarm signal.

G.5 Fire parameters: the relation between the m value and the y value and the relation between the m value and the test time shall lie within the shaded areas of Figure G.2 a) and Figure G.2 b).

H Annex H (normative) Test fire SH3 — polyurethane plastic fire

H.1 Fuel: flexible polyurethane foam plastic without flame retardant, of a mass density of about 20 kg per cubic metre.

H.2 Arrangement: three pads of 50 cm by 50 cm by 2 cm are stacked one on another. The number of pads may be varied to obtain a more effective test flame. The base plate is aluminium foil with its edges turned up.

H.3 Ignition fuel: a small quantity of clean combustible material is used as an accelerant, for example 5 ml of methylated spirit.

H.4 Ignition point: the lowest pad.

H.5 End of test: the y value reaches 6, or all the alarms have emitted a fire alarm signal.

H.6 Fire parameters: the relation between the m value and the y value and the relation between the m value and the test time shall lie within the shaded areas of Figure H.1 a) and Figure H.1 b).

I Annex I (normative) Test fire SH4 — n-heptane fire

I.1 Fuel: n-heptane of purity not less than 99 % with 3 % by volume of toluene of purity not less than 99 %; the volume fraction may be varied to obtain a more effective test flame.

I.2 Arrangement: the fuel is placed in a vessel made of 2 mm steel plate with a base area of about 1100 square centimetres, that is 33 cm by 33 cm, and a height of 5 cm.

I.3 Mass: the total mass of the mixed fuel is 650 g.

I.4 Method of ignition: flame or electric spark.

I.5 End of test: the y value reaches 6, or all the alarms have emitted a fire alarm signal.

I.6 Fire parameters: the relation between the m value and the y value and the relation between the m value and the test time shall lie within the shaded areas of Figure I.1 a) and Figure I.1 b); and if at the end of the test the y value has reached 6 but an alarm has not yet given an alarm signal, the only criterion for judging the test fire valid is that the m value is less than or equal to 1.1 dB/m.

J Annex J (normative) Impact test apparatus

J.1 The main body of the test apparatus, shown in Figure J.1, is a pendulum mechanism. The hammer head is made of hard aluminium alloy AlCu4SiMg, solution treated and aged, and is a hexahedron with one bevelled impact face. The swing arm of the hammer head is fixed to a steel hub carried on ball bearings, the bearings being fitted on a fixed steel shaft in a hard steel frame; the frame shall be built so that the pendulum can swing freely when no alarm is fitted.

J.2 The hammer head measures 94 mm long, 76 mm wide and 50 mm high. The angle between the bevelled face of the head and its longitudinal axis is (60 +/- 1)°. The outside diameter of the swing arm is (25 +/- 0.1) mm and its wall thickness (1.6 +/- 0.1) mm.

J.3 The radial distance from the longitudinal axis of the hammer head to the axis of rotation is 305 mm, and the axis of the swing arm shall be perpendicular to the axis of rotation. A steel hub of 102 mm outside diameter and 200 mm length is fitted concentrically on a steel shaft of 25 mm diameter, the accuracy of the shaft diameter depending on the dimensional tolerance of the bearings used. Two steel counterweight arms of 20 mm outside diameter and 185 mm length, projecting 150 mm, are fitted to the hub on the side opposite the swing arm, and an adjustable counterweight is fitted on them so that the hammer head can be balanced against the arms. An aluminium alloy pulley 12 mm thick and 150 mm in diameter is fitted to one end of the hub, and a cable is wound on the pulley with one end fixed to the pulley and a working weight attached to the other.

J.4 The horizontal mounting plate that carries the alarm is supported by the steel frame and can be adjusted up and down so that the centre of the impact face of the hammer head strikes the alarm horizontally, as shown in Figure J.1. In use, the alarm and the mounting plate are first set as shown in Figure J.1, the plate is then clamped to the frame, the working weight is taken off and the pendulum mechanism balanced by adjusting the counterweight. After balancing, the swing arm is drawn to the horizontal position and the working weight attached; when the mechanism is released the working weight turns the hammer head through three half-turns of a right angle each, that is 3 pi over 2 radians, onto the alarm. The mass of the working weight is given by a formula in which the mass is in kilograms and the effective radius of the pulley is in metres. When that radius is 0.075 m the mass of the working weight is about 0.55 kg and the mass of the hammer head about 0.79 kg.

K Annex K (normative) Dust environment simulation test apparatus

K.1 The test dust is Arizona test dust, fine grade, meeting GB/T 28957.1-2023.

K.2 The dust environment simulation test apparatus and the test arrangement are shown in Figure K.1 and Figure K.2. The apparatus comprises the measuring zone, an optional optical smoke density meter, a dust concentration meter, the air flow, a dust generator, an air compressor, a trace dust make-up, a circulating pump, a heater, an oscillator, an electric valve, a dust discharge port and a control cabinet.

K.3 The apparatus shall be able to keep the temperature, humidity and air velocity in the measuring working zone within the values the tests require.

K.4 Trace dust make-up through the dust generator keeps the dust concentration in the apparatus within the values the tests require.