LPS 1274 Issue 1.1 Testing procedures for the LPCB approval and listing of carbon monoxide / heat multisensor fire detectors using electrochemical cells

Carbon monoxide (CO) is a known product of the combustion of carbon-based materials. It is an invisible and odourless gas which, unlike smoke, cannot be detected by humans. When present in the atmosphere in sufficient quantity, CO can seriously impair the ability of people to react in a fire situation and can eventually lead to their death. In certain conditions, in which the fire is starved of oxygen and develops slowly, a dangerous concentration of CO may be present in the atmosphere before other fire detectors are able to operate. This can make CO fire detectors suitable for certain applications in the protection of life.

Although there are many techniques for sensing and detecting the presence of CO, not all of the available sensor types are suitable for use in fire detectors. One sensor, the electrochemical cell, has proven suitable for fire detection applications, and is being used in commercially available products. The electrochemical cell does however have known weaknesses. These include sensitivity to substances other than CO, that may be present in the atmosphere. In addition, cell performance may be degraded by long-term exposure to very low or very high humidity.

This standard has been drafted to allow the evaluation of detectors using electrochemical cells and includes tests specifically intended to demonstrate that the electrochemical cell used has adequate performance for fire detection applications. Other types of CO sensor may be suitable for use in fire detectors. However, the tests in this standard may not be sufficient to demonstrate the robustness of any other type of sensor.

A particular strength of electrochemical cells is that they do not produce a response when subjected to short-term exposure to steam or condensation, and can therefore be used in some applications in which smoke detectors would be unsuitable. To verify this strength, a cyclic damp heat operational test is included in the standard.

3.1 CO Response threshold value

The CO concentration in the proximity of the specimen at the moment that it generates an alarm signal, when tested as described in 5.1.5.

NOTE: The response threshold value may depend on signal processing in the detector and in the control and indicating equipment.

In order to comply with this standard, the detector shall meet the requirements of this clause, which shall be verified by visual inspection or engineering assessment, shall be tested as described in Clause 5 and shall meet the requirements of the tests.

Individual alarm indication

Each detector shall be provided with an integral red visual indicator, by which the individual detector that released an alarm, can be identified, until the alarm condition is reset. Where other conditions of the detector can be visually indicated, they shall be clearly distinguishable from the alarm indication, except when the detector is switched into a service mode. For detachable detectors, the indicator may be integral with the

base or the detector head. The visual indicator shall be visible from a distance of 6 m directly below the detector, in an ambient light intensity up to 500 lux.

Connection of ancillary devices

Where the detector provides for connections to ancillary devices (e.g. remote indicators, control relays), open- or short-circuit failures of these connections shall not prevent the correct operation of the detector.

Monitoring of detachable detectors

For detachable detectors, a means shall be provided for a remote monitoring system (e.g. the control and indicating equipment) to detect the removal of the head from the base, in order to give a fault signal.

Manufacturer’s adjustments

It shall not be possible to change the manufacturer’s settings except by special means (e.g. the use of a special code or tool) or by breaking or removing a seal.

On-site adjustment of response behaviour

If there is provision for on-site adjustment of the response behaviour of the detector then:

  1. for each setting at which the manufacturer claims compliance with this standard, the detector shall comply with the requirements of this standard, and access to the adjustment means shall only be possible by the use of a code or special tool or by removing the detector from its base or mounting;
  2. any setting(s) at which the manufacturer does not claim compliance with this standard, shall only be accessible by the use of a code or special tool, and it shall be clearly marked on the detector or in the associated data, that if these setting(s) are used, the detector does not comply with the standard.

Rate-sensitive CO response behaviour

The CO response threshold value of the detector may depend on the rate of change of CO concentration in the vicinity of the detector. Such behaviour may be incorporated in the detector design to improve the discrimination between ambient CO levels and those generated by a fire. If such rate sensitive behaviour is included then it shall not lead to a significant reduction in the detector’s sensitivity to fires, nor to a significant increase in the probability of false alarm.

Since it is not practical to make tests with all possible rates of increase in CO concentration, an assessment of the detector’s rate sensitivity shall be made by analysis of the circuit/software, and/or physical tests and simulations.

Additional requirements for software controlled detectors

For detectors which rely on software control in order to fulfil the requirements of this standard, the requirements of 4.10.2, 4.10.3 and 4.10.4 shall be met.

  • Software documentation
  • Design overview

The manufacturer shall submit documentation which gives an overview of the software design. This documentation shall be in sufficient detail for the design to be inspected for compliance with this standard and shall include at least the following:

  • Software design

In order to ensure the reliability of the detector, the following requirements for software design shall apply:

  1. the software shall have a modular structure;
  2. the design of the interfaces for manually and automatically generated data shall not permit invalid data to cause error in the program operation; c) the software shall be designed to avoid the occurrence of deadlock of the program flow.

The storage of programs and data

The program necessary to comply with this standard and any pre-set data, such as manufacturer’s settings, shall be held in non-volatile memory. Writing to areas of memory containing this program and data shall only be possible by the use of some special tool or code and shall not be possible during normal operation of the detector.

Atmospheric conditions for tests

Unless otherwise stated in a test procedure, the testing shall be carried out after the test specimen has been allowed to stabilize in the standard atmospheric conditions for testing as described in IEC 60068-1:1988+A1:1992 as follows:

  1. temperature: (15 to 35) °C;
  2. relative humidity: (25 to 75) %;
  3. air pressure: (86 to 106) kPa.

NOTE: If variations in these parameters have a significant effect on a measurement, then such variations should be kept to a minimum during a series of measurements carried out as part of one test on one specimen.

Operating conditions for tests

If a test method requires a specimen to be operational, then the specimen shall be connected to suitable supply and monitoring equipment with characteristics as required by the manufacturer’s data. Unless otherwise specified in the test method, the supply parameters applied to the specimen shall be set within the manufacturer’s specified range(s) and shall remain substantially constant throughout the tests. The value chosen

for each parameter shall normally be the nominal value, or the mean of the specified range. If a test procedure requires a specimen to be monitored to detect any alarm or fault signals, then connections shall be made to any necessary ancillary devices (e.g. through wiring to an end-of-line device for conventional detectors) to allow a fault signal to be recognised.

NOTE: The details of the supply and monitoring equipment and the alarm criteria used should be given in the test report.

Mounting arrangements

The specimen shall be mounted by its normal means of attachment and in its normal orientation in accordance with the manufacturer’s instructions. If these instructions describe more than one method of mounting, or more than one acceptable orientation, then the method considered to be most unfavourable shall be chosen for each test.

  • Tolerances

Unless otherwise stated, the tolerances for the environmental test parameters shall be as given in the basic reference standards for the test (e.g. the relevant part of IEC 60068).

If a requirement or test procedure does not specify a tolerance or deviation limits, then deviation limits of ± 5 % shall be applied.

Measurement of CO response threshold value

The specimen, for which the CO response threshold value is to be measured, shall be installed in the CO tunnel, described in Annex A, in its normal operating position, by its normal means of attachment. The orientation of the specimen, relative to the direction of airflow, shall be the least sensitive orientation, as determined in the directional dependence test, unless otherwise specified in the test procedure.

Before commencing each measurement, the CO tunnel shall be purged to ensure that the tunnel and the specimen are free from CO.

The air velocity in the proximity of the specimen shall be (0.35 ± 0.15) m s-1 during the measurement, unless otherwise specified in the test procedure.

Unless otherwise specified in the test procedure, the air temperature in the tunnel shall be (23 ± 5) °C and shall not vary by more than 5 K for all the measurements on a particular detector type.

The specimen shall be connected to its supply and monitoring equipment as described in 5.1.2, and shall be allowed to stabilise for a period of at least 15 min, unless otherwise specified by the manufacturer.

CO shall be introduced into the tunnel such that the rate of increase of CO concentration is between 1 ppm min-1 and 6 ppm min-1. For detectors whose response is rate sensitive, the manufacturer may specify a rate of increase within this range to ensure that the measured CO response threshold value is representative of the static CO response threshold value of the detector.

The rate of increase in CO concentration shall be similar for all measurements on a particular detector type.

The CO concentration at the moment that the specimen gives an alarm shall be recorded as c (ppm). This shall be taken as the CO response threshold value.

Measurement of heat sensor response

The heat response value of the specimen shall be measured using the method described in section 5.1.5 of EN 54-5: 2000.

NOTE 1 Detectors for which the manufacturer claims compliance with EN 54-5: 2000 should be subjected to the tests required in EN 54-5: 2000. In such cases, the response times measured in those tests may be used as the heat response values for the purposes of this standard.

The heat response value may be assessed as

  1. the time taken from the start of the temperature increase to the point at which the heat signal reaches a level specified by the manufacturer, or the detector gives an alarm signal

or

  1. the change in signal level produced in a certain time.

NOTE 2: In the case of a), a shorter time will represent a higher sensitivity. In the case of b) a larger change will represent a higher sensitivity.

The measured heat response value shall be recorded as t.

Provision for tests

The following shall be provided for testing compliance with this standard:

  1. For detachable detectors: twenty-four detector heads and bases; for non-detachable detectors: twenty-four specimens;
  2. The data required in 4.9.

NOTE 1: Detachable detectors comprise at least two parts; a base (socket) and a head (body). If the specimens are detachable detectors, then the two, or more, parts together are regarded as a complete detector.

  1. c) Means to enable a quantitative measurement of the heat response value of the temperature sensing element(s) of the detector according to 5.1.6.

Repeatability of CO response

  • Object

To show that the detector has stable behaviour with respect to its CO sensitivity even after a number of alarm conditions.

  • Test procedure

The CO response threshold value of the specimen to be tested shall be measured as described in 5.1.5 six times.

The specimen’s orientation relative to the direction of airflow is arbitrary, but it shall be the same for all six measurements.

The maximum response threshold value shall be designated cmax, the minimum value shall be designated cmin.

  • Requirements

The ratio of the CO response threshold values cmax : cmin shall be not greater than 1.6. The lower CO response threshold value cmin shall be not less than 30 ppm

Directional dependence of CO response

  • Object

To confirm that the CO sensitivity of the detector is not unduly dependent on the direction of airflow around the detector.

  • Test procedure

The CO response threshold value of the specimen to be tested shall be measured eight times as described in 5.1.5, the specimen being rotated 45° about its vertical axis between each measurement, so that the measurements are taken for eight different orientations relative to the direction of air flow.

The maximum CO response threshold value shall be designated cmax , the minimum value shall be designated cmin .

The orientations, for which the maximum and minimum CO response threshold values were measured, shall be noted.

In the following tests the orientation for which the maximum CO response threshold was measured is referred to as the least sensitive orientation, and the orientation for which the minimum CO response threshold was measured is referred to as the most sensitive orientation.

5.3.3 Requirements

The ratio of the CO response threshold values cmax : cmin shall not be greater than 1.6. The lower CO response threshold value cmin shall not be less than 30 ppm.

Directional Dependence of Heat Response

To confirm that the heat sensitivity of the detector is not unduly dependent on the direction of airflow around the detector.

The specimen shall be tested as described in 5.1.6 at a rate of rise of air temperature of 10 K min-1. Eight such tests shall be made, the specimen being rotated about a vertical axis by 45° between successive tests so that tests are made with eight different orientations. Before each test the specimen shall be stabilised to 25°C. The heat response value at each of the eight orientations shall be recorded. The orientations at which the maximum and minimum heat response values were measured shall be noted.

The maximum heat response value shall be designated tmax , the minimum value shall be designated tmin .

In the following tests the orientation for which the maximum response time, or the minimum change in signal level was measured is referred to as the least sensitive heat orientation. The orientation for which the minimum response time, or the maximum change in signal level was measured is referred to as the most sensitive heat orientation.

The ratio of the heat response values tmax : tmin shall not be greater than 1.3, or shall not be greater than the value for which the manufacturer can demonstrate that the resulting change in the CO response threshold value is not more than a factor of 1.6.

Lower Limit of Heat response temperature/times

To confirm that detectors are not more sensitive to heat alone, without the presence of CO, than is allowed in EN 54-5: 2000

Reproducibility of CO response

  • To show that the CO sensitivity of the detector does not vary unduly from specimen to specimen and to establish CO response threshold value data for comparison with the CO response threshold values measured after the environmental tests.

The CO response threshold value of each of the test specimens shall be measured as described in 5.1.5.

The mean of these response threshold values shall be calculated and shall be designated c

The maximum response threshold value shall be designated cmax the minimum value shall be designated cmin .

Reproducibility of heat response

To show that the heat sensitivity of the detector does not vary unduly from specimen to specimen and to establish heat response value data for comparison with the heat response values measured after the environmental tests

Each specimen shall be tested as described in 5.1.6 at a rate of rise of air temperature of 20 K min-1 and the heat response value recorded.

The maximum heat response value shall be designated tmax and the minimum value shall be designated tmin.

Long term stability of CO response

Connect the detector to suitable supply and monitoring equipment and place it in an environment free of CO and atmospheric contaminants. Measure the CO response threshold value, as described in 5.1.5, at 28 days, 56 days and 84 days from the start of the test. Designate the highest of the values measured in this test and that measured for the same detector in the reproducibility test as cmax. Designate the lowest of the values measured in this test and that measured for the same detector in the reproducibility test

Variation in supply parameters

To show that, within the specified range(s) of the supply parameters (e.g. voltage), the sensitivity of the detector is not unduly dependent on these parameters.

The CO response threshold value of the specimen shall be measured as described in 5.1.5, at the upper and lower limits of the supply parameter (e.g. voltage) range(s) specified by the manufacturer.

The maximum CO response threshold value shall be designated cmax and the minimum value shall be designated cmin .

The heat response value shall be measured as described in 5.1.6 at a rate of rise of air temperature of 20 K min-1 at the upper and lower limits of the supply parameter (e.g. voltage) range(s) specified by the manufacturer.

The maximum heat response value shall be designated tmax, and the minimum shall be designated tmin.

The lower CO response threshold value cmin shall not be less than 30 ppm.

The ratio of the heat response values tmax : tmin shall not be greater than 1.3, or shall not be greater than the value for which the manufacturer can demonstrate that the resulting change in the CO response threshold value is not more than a factor of 1.6.

Air movement

To show that the CO sensitivity of the detector is not unduly affected by the rate of the airflow.

The CO response threshold value of the specimen to be tested shall be measured as described in 5.1.5 in the most and least sensitive orientations, and shall be appropriately designated c(0.35)max and c(0.35)min

5.11 Dry heat (operational)

To demonstrate the ability of the detector to function correctly at high ambient temperatures appropriate to the anticipated service environment.

The specimen to be tested shall be installed in the CO tunnel described in Annex A, in its least sensitive orientation, with an initial air temperature of (23 ± 5) °C, and shall be connected to its supply and monitoring equipment.

The air temperature in the tunnel shall then be increased to (55 ± 2) °C, at a rate not exceeding 1 Kmin-1, and maintained at this temperature for 2 h.

The CO response threshold value shall then be measured as described in 5.1.5 but with the temperature at (55 ± 2) °C.

The greater of the CO response threshold value measured in this test and that measured for the same specimen in the reproducibility test, shall be designated cmax , and the lesser shall be designated cmin .

No alarm or fault signal shall be given during the period that the temperature is increasing to the conditioning temperature or during the conditioning period until the CO response threshold value is measured.

The ratio of the CO response threshold values cmax : cmin shall not be greater than 1.6.

Cold (operational)

To demonstrate the ability of the detector to function correctly at low ambient temperatures appropriate to the anticipated service environment.The specimen to be tested shall be installed in the CO tunnel described in Annex A, in its least sensitive orientation, with an initial air temperature of (23 ± 5) °C, and shall be connected to its supply and monitoring equipment.

The air temperature in the tunnel shall then be decreased to (-10 ± 3) °C, at a rate not exceeding 1 Kmin-1, and maintained at this temperature for 2 h.

The response threshold value shall then be measured as described in 5.1.5 but with the temperature at (-10 ± 3) °C.

The greater of the response threshold value measured in this test and that measured for the same specimen in the reproducibility test, shall be designated cmax , and the lesser shall be designated cmin .

No alarm or fault signal shall be given during the transition to the conditioning temperature or during the period at the conditioning temperature until the CO response threshold value is measured.

The ratio of the CO response threshold values cmax : cmin shall not be greater than 1.6.

Damp heat, cyclic (operational)

To demonstrate the ability of the detector to function correctly at high relative humidities (with condensation), which can occur for short periods in the anticipated service environment.

The test apparatus and procedure shall be as described in IEC 60068-2-30:1980 +A1:1985, using the Variant 1 test cycle and controlled recovery conditions, and as described below.

State of the specimen during conditioning

The specimen shall be mounted as described in 5.1.3 and shall be connected to supply and monitoring equipment as described in 5.1.2.

After the recovery period the following measurements shall be made.

The CO response threshold value of the specimen shall be measured as described in 5.1.5

Damp heat, steady state (endurance)

To demonstrate the ability of the detector to withstand the long term effects of humidity in the service environment. (e.g. changes in electrical properties of materials, chemical reactions involving moisture, galvanic corrosion, dilution and expansion of cell electrolyte etc.)

The test apparatus and procedure shall be as described in IEC 60068-2-56:1988 Test Cb or IEC 60068-2-3:1969+A1: 1984 Test Ca, and as described below.

After a recovery period, of between 1 h and 2 h in standard laboratory conditions, the following measurements shall be made.

The CO response threshold value shall be measured as described in 5.1.5.

The greater of the CO response threshold value measured in this test and that measured for the same specimen in the reproducibility test, shall be designated cmax , and the lesser shall be designated cmin .

The heat response value shall be measured as described in 5.1.6 at a rate of rise of air temperature of 20 K min-1.

Low humidity, steady state (endurance)

To demonstrate the ability of the detector to withstand long periods of low humidity in the service environment. (i.e. to evaluate its resistance to the drying out of electrolyte in the electrochemical cell.)

The specimen shall be mounted as described in 5.1.3 but shall not be supplied with power during the conditioning.

The following conditioning shall be applied:

Temperature:                                         (25 ± 3) °C

Relative Humidity: (11 ± 1) % Duration:   21 days

NOTE: The relative humidity specified for this test can be maintained using a saturated solution of lithium chloride inside a sealed enclosure.

After a recovery period of between 1 h and 2 h in standard laboratory conditions, the CO response threshold value shall be measured as described in 5.1.5.

The greater of the CO response threshold value measured in this test and that measured for the same specimen in the reproducibility test, shall be designated cmax , and the lesser shall be designated cmin .

No fault signal, attributable to the endurance conditioning, shall be given on reconnection of the specimen.

The ratio of the CO response threshold values cmax : cmin shall not be greater than 1.6.

Sulphur dioxide SO2 corrosion (endurance)

To demonstrate the ability of the detector to withstand the corrosive effects of sulphur dioxide as an atmospheric pollutant.

The test apparatus and procedure shall be as described in IEC 60068-2-42:1982 Test Kc, except that the conditioning shall be as described below.

Temperature: Relative humidity: SO2 concentration: Duration:

The specimen shall be mounted as described in 5.1.3. It shall not be supplied with power during the conditioning, but it shall have untinned copper wires, of the appropriate diameter, connected to sufficient terminals, to allow the final measurement to be made, without making further connections to the specimen.

The ratio of the heat response values tmax : tmin shall not be greater than 1.3, or shall not be greater than the value for which the manufacturer can demonstrate that the resulting change in the CO response threshold value is not more than a factor of 1.6

Shock (operational)

To demonstrate the immunity of the detector to mechanical shocks, which are likely to occur, albeit infrequently, in the anticipated service environment.

Impact (operational)

To demonstrate the immunity of the detector to mechanical impacts upon its surface, which it may sustain in the normal service environment, and which it can reasonably be expected to withstand.

The test apparatus shall consist of a swinging hammer incorporating a rectangular-section aluminium alloy head (Aluminium alloy Al Cu4 Si Mg complying with ISO 209-1:1989, solution treated and precipitation treated condition) with the plane

impact face chamfered to an angle of 60° to the horizontal, when in the striking position (i.e. when the hammer shaft is vertical). The hammer head shall be (50 ± 2.5) mm high, (76 ± 3.8) mm wide and (80 ± 4) mm long at mid height as shown in Figure E.1. A suitable apparatus is described in Annex C.

The specimen shall be rigidly mounted to the apparatus by its normal mounting means and shall be positioned so that it is struck by the upper half of the impact face when the hammer is in the vertical position (i.e. when the hammerhead is moving horizontally). The azimuthal direction and position of impact, relative to the specimen shall be chosen as that most likely to impair the normal functioning of the specimen. The specimen shall be connected to its supply and monitoring equipment as described in 5.1.2.

vibration, sinusoidal, (operational)

To demonstrate the immunity of the detector to vibration at levels considered appropriate to the normal service environment.

The test apparatus and procedure shall be as described in IEC 60068-2-6:1995+Corr.: 1995 Test Fc, and as described below.

(10 to 150) Hz 5 m s-2 (» 0.5 gn) 3

1 octave min-1 1 per axis

The specimen shall be mounted on a rigid fixture as described in 5.1.3 and shall be connected to its supply and monitoring equipment as described in 5.1.2. The vibration shall be applied in each of three mutually perpendicular axes, in turn. The specimen shall be mounted so that one of the three axes is perpendicular to its normal mounting plane.

Vibration, sinusoidal (endurance)

To demonstrate the ability of the detector to withstand the long term effects of vibration at levels appropriate to the service environment.

The specimen shall be mounted on a rigid fixture as described in 5.1.3, but shall not be supplied with power during conditioning. The vibration shall be applied in each of three mutually perpendicular axes, in turn. The specimen shall be mounted so that one of the three axes is perpendicular to its normal mounting axis.

The following conditioning shall be applied:

Frequency range: Acceleration amplitude: Number of axes: Sweep rate:

Number of sweep cycles:

The CO response threshold value shall be measured as described in 5.1.5.

The greater of the response threshold value measured in this test and that measured for the same specimen in the reproducibility test, shall be designated cmax , and the lesser shall be designated cmin .

The heat response value shall be measured as described in 5.1.6 at a rate of rise of air temperature of 20 .

Electromagnetic Compatibility (EMC), Immunity tests (operational)

The following EMC immunity tests shall be carried out, as described in EN 50130-4:1995+A 1: 1998:

For these tests the criteria for compliance specified in EN 50130-4:1995+A1:1998 and the following shall apply:

1) The functional test, called for in the initial and final measurements, shall be as follows:

The CO response threshold value shall be measured as described in 5.1.5.

The greater of the response threshold value measured in this test and that measured for the same specimen in the reproducibility test, shall be designated cmax , and the lesser shall be designated cmin .;

The heat response value shall be measured as described in 5.1.6 at a rate of rise of air temperature of 20 K min-1.

The greater of the heat response values measured in this test and that measured for the same specimen in the reproducibility test, shall be designated tmax, and the lesser shall be designated tmin.

  • The required operating condition shall be as described in 5.1.2;
  • The acceptance criteria for the functional test after the conditioning shall be as follows

The ratio of the CO response threshold values cmax : cmin shall not be greater than 1.6.

The ratio of the heat response values tmax : tmin shall not be greater than 1.3, or shall not be greater than the value for which the manufacturer can demonstrate that the resulting change in the CO response threshold value is not more than a factor of 1.6.

Fire sensitivity

To show that the detector has adequate sensitivity to a broad spectrum of fire types as required for general application in fire detection systems for buildings.

The specimens are mounted in a standard fire test room and are exposed to a series of test fires designed to produce smoke, heat and CO.

Fire test room

The fire sensitivity tests shall be conducted in a rectangular room with a flat horizontal ceiling, and the following dimensions:

  • Length: 9 m to 11 m;
  • Width: 6 m to 8 m;
  • Height: 3.8 m to 4.2 m.
  • Test fires

The specimens shall be subjected to the five test fires as described in Annexes E to I. The first four fires are TF2, TF3, TF4 and TF5 from EN 54-7:2000 while the fifth is specific to CO fire detectors. (See Annexes E to I). The type, quantity and arrangement of the fuel and the method of ignition are described in Annexes E to I, for each test fire, along with the end of test condition and the required profile curve limits.

In order to be a valid test fire, the development of the fire shall be such that the profile curves of m against y, m against time, and c against time fall within the specified limits, up to the time when all of the specimens have generated an alarm signal or the end of test condition is reached, which ever is the earlier. If these conditions are not met then the test is invalid and shall be repeated. It is permissible, and may be necessary, to adjust the quantity, condition (e.g. moisture content) and arrangement of the fuel to obtain valid test fires.

Mounting of the specimens

The four specimens (Nos. 21, 22, 23, 24) shall be mounted on the fire test room ceiling in the designated area (see Annex D). The specimens shall be mounted in accordance with the manufacturer’s instructions, such that specimens 21 and 22 are in the least sensitive orientation for heat, and specimens 23 and 24 are in the least sensitive orientation for CO, relative to an assumed airflow from the centre of the room to the specimen.

Each specimen shall be connected to its supply and monitoring equipment, as described in 5.1.2, and shall be allowed to stabilise in its quiescent condition before the start of each test fire.

Before each test fire the room shall be ventilated with clean air until it is free from smoke and CO, and so that the conditions listed below can be obtained.

The ventilation system shall then be switched off and all doors, windows and other openings shall be closed. The air in the room shall then be allowed to stabilize, and the following conditions shall be obtained before the test is started:

Recording of the fire parameters and response values

During each test fire the following fire parameters shall be recorded continuously or at least once per second.

The alarm signal given by the supply and monitoring equipment shall be taken as the indication that a specimen has responded to the test fire.

The time of response of each specimen shall be recorded along with the fire parameters ya, ma, ca and ATa, at the moment of response.

All four specimens shall generate an alarm signal, in each test fire, before the specified end of test condition is reached.

Assessment of exposure to chemical agents at environmental concentrations

To demonstrate the ability of the detector to withstand the effects of exposure to atmospheric pollutants or chemicals which may be encountered in the service environment.

The specimen shall be mounted as described in 5.1.3 and shall be connected to supply and monitoring equipment as described in 5.1.2.

The specimen shall be subjected to each of the chemical exposures specified in Table 2 Table 2

The specimen shall be monitored during each of the conditioning periods to detect any alarm or fault signals.

Assessment of exposure to chemical agents which may be present during a fire

To demonstrate that chemical agents that may be present during a fire do not unduly affect the ability of the detector to detect the CO produced by the fire, nor cause permanent changes in sensitivity.

The specimen shall be mounted as described in 5.1.3 and shall be connected to supply and monitoring equipment as described in 5.1.2.

Measurements of the detector’s response threshold shall be taken during and after exposure to the chemical agents in Table 3 in order to determine if there is a detrimental effect on the detector’s sensitivity.

Assessment of exposure to high concentrations of carbon monoxide

To demonstrate the ability of the detector to withstand exposure to high levels of carbon monoxide which may be encountered during a fire condition.

The specimen shall be mounted as described in 5.1.3 and shall be connected to supply and monitoring

LPS 1274 Issue 1.1 Testing procedures for the LPCB approval and listing of carbon monoxide / heat multisensor fire detectors using electrochemical cells

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