LPS 1279 Issue 1.1 Testing procedures for the LPCB approval and listing of point multisensor fire detectors using optical or ionization smoke sensors and electrochemical cell CO sensors and, optionally, heat sensors

Smoke detectors using ionization or optical sensors, and complying with EN54-7, are well established for the protection of life and property. Even so, they can respond to stimuli other than smoke and in some circumstances can be prone to false alarms. False alarm rates are usually minimised by careful application, giving some limitations in use, and occasionally with a reduction in protection provided.

It is generally accepted that fire detectors using CO sensors alone, while suitable for the detection of smouldering fires involving carbonaceous fuels, can be relatively insensitive to free-burning fires supported by a plentiful supply of oxygen. This limitation can be largely overcome by the inclusion of a heat sensor whose output is combined in some way with that of the CO sensor. Performance requirements for CO fire detectors and for CO/heat multisensor detectors can be found in LPS1265 and LPS1274 respectively.

Although the CO/heat multisensor is capable of responding to free-burning fires, it can still be relatively insensitive to low-temperature fires that produce large amounts of visible smoke but low concentrations of CO and little heat. This limitation prevents the CO/heat multisensor being a true replacement for a smoke detector in life safety applications.

Most false alarm sources that affect smoke detectors do not produce CO. It is possible therefore that by adding a CO sensor to a smoke detector, and combining its output in some way with that of the smoke sensor, the incidence of false alarms can be reduced. This reduction may be achieved while providing the ability to respond to a broader range of fire types than is possible with either a smoke or CO detector alone.

It may be possible to improve the performance even further by adding a heat sensor to assist in the response to clean-burning high energy fires. This improvement is seen as secondary to the overall performance and for this reason the heat sensor is treated as optional for compliance with this standard.

This standard, like existing standards for smoke and CO fire detectors, includes a number of fire tests. However, this standard demands a broader response than current standards in order to demonstrate that the potential benefits of the sensor combination have been achieved. To this end the standard fires TF2, TF3, TF4 and TF5 from EN54- 7 are used, and are supplemented by a deep-seated smouldering fire and a low- temperature liquid fire producing black smoke.

This Standard specifies requirements, test methods and performance criteria for the LPCB approval and listing of point multisensor fire detectors that incorporate at least an optical or ionization smoke sensor and an electrochemical cell for sensing carbon monoxide, and optionally one or more heat sensors, for use in fire detection and fire alarm systems for buildings.

For smoke and CO multisensor fire detectors using different sensor technologies, this standard should only be used for guidance. Smoke and CO multisensor fire detectors with special characteristics and developed for specific risks are not covered by this standard.

CO response threshold value

The CO concentration in the proximity of the specimen at the moment that it generates an alarm signal, or a signal specified by the manufacturer, when tested as described in 5.1.6.

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

Smoke response threshold value

The smoke concentration in the proximity of the specimen at the moment that it generates an alarm signal, or a signal specified by the manufacturer, when tested as described in 5.1.5.

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, which 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.

NOTE: These adjustments may be carried out at the detector or at the control and indicating equipment.

Protection against the ingress of foreign bodies

The detector shall be so designed that a sphere of diameter (1.3 ± 0.05) mm cannot pass into the smoke sensor chamber(s).

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.

The detector shall be deemed to meet the requirements of this clause if this assessment shows that:

1. for any rate of increase in CO concentration less than 1 ppm per minute the detector will signal an alarm condition before the CO concentration reaches 60 ppm, and
2. the detector does not produce an alarm condition when subjected to a step change in CO concentration of 10 ppm, superimposed on a background level between 0 and 5 ppm.

Smoke response to slowly developing fires

The provision of “drift compensation” of the smoke sensor (e.g. to compensate for sensor drift due to the build up of dirt in the detector), shall not lead to a significant reduction in the detector’s sensitivity to smoke from slowly developing fires.

Since it is not practical to make tests with very slow increases in smoke density, an assessment of the detector’s response to slow increases in smoke density shall be made by analysis of the circuit/software, and/or physical tests and simulations.

The detector shall be deemed to meet the requirements of this clause if this assessment shows that:

1. for any rate of increase in smoke density R, which is greater than >4/4 per hour (where A is the detector’s initial uncompensated response threshold value), the time for the detector to give an alarm does not exceed 1.6 x A/R by more than 100 s; and
2. the range of compensation is limited such that, throughout this range, the compensation does not cause the response threshold value of the detector to exceed its initial value by a factor greater than 1.6.

Additional requirements for software controlled detectors

For detectors that rely on software control in order to fulfil the requirements of this standard, the requirements of 4.12.2, 4.12.3 and 4.12.4 shall be met.

• Design overview

The manufacturer shall submit documentation that 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:

1. a functional description of the main program flow (e.g. as a flow diagram or structogram) including:
   1. a brief description of the modules and the functions that they perform;
   2. the way in which the modules interact;
   3. the overall hierarchy of the program;
   4. the way in which the software interacts with the hardware of the detector;
   5. the way in which the modules are called, including any interrupt processing.
2. a description of which areas of memory are used for the various purposes (e.g. the program, site specific data and running data);
3. a designation, by which the software and its version can be uniquely identified.

• Design detail

The manufacturer shall have available detailed design documentation, which only needs to be provided if required by the testing authority. It shall comprise at least the following:

1. an overview of the whole system configuration, including all software and hardware components;
2. a description of each module of the program, containing at least:
   1. the name of the module;
   2. a description of the tasks performed;
   3. a description of the interfaces, including the type of data transfer, the valid data range and the checking for valid data.
3. full source code listings, as hard copy or in machine-readable form (e.g. ASCII- code), including all global and local variables, constants and labels used, and sufficient comment for the program flow to be recognised;
4. details of any software tools used in the design and implementation phase (e.g. CASE-tools, compilers).

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;
3. the software shall be designed to avoid the occurrence of deadlock of the program flow.

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.

Site-specific data shall be held in memory which will retain data for at least two weeks without external power to the detector, unless provision is made for the automatic renewal of such data, following loss of power, within 1 h of power being restored.

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 stabilise 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.

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 smoke response threshold value

The smoke response threshold value of the specimen shall be measured using the method described in section 5.1.5 of EN54-7. The CO level in the smoke tunnel throughout the test shall not exceed 3 ppm.

The aerosol density at the moment that the specimen gives an alarm signal, or a signal specified by the manufacturer, shall be recorded as m (dB m^– ) for detectors using scattered or transmitted light, or as y for detectors using ionization. This shall be taken as the smoke response threshold value.

Measurement of CO response threshold value

The CO response threshold value shall be measured using the method described in section 5.1.5 of LPS1265.

The CO concentration at the moment that the specimen gives an alarm signal, or a signal specified by the manufacturer, shall be recorded as c (ppm). This shall be taken as the CO response threshold value.

Measurement of heat sensor response value

The heat response value of the specimen shall be measured using the method described in section 5.1.5 of EN54-5.

Provision for tests

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

1. a) For detachable detectors: twenty-four detector heads and bases; For non-detachable detectors: twenty-four specimens;
2. the smoke response threshold value of the detector according to 5.1.5;
3. the CO response threshold value of the detector according to 5.1.6;
4. the heat response value of the temperature sensing element(s) of the detector according to 5.1.7.

The specimens submitted shall be representative of the manufacturer’s normal production with regard to their construction and calibration.

The specimens shall be tested according to the following test schedule (see Table 1). After the reproducibility test, the two specimens having the lowest CO sensitivity (i.e. those with the highest CO response threshold values) shall be numbered 21 and 22, and the two specimens having the lowest smoke sensitivity (i.e. those with the highest smoke response threshold values) shall be numbered 23 and 24. The others shall be numbered 1 to 20 arbitrarily:

Repeatability of smoke response

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

The smoke 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 smoke response threshold value shall be designated mmax, for detectors using scattered or transmitted light, or as y_max for detectors using ionization. The minimum smoke response threshold value shall be designated mmin, for detectors using scattered or transmitted light, or as y_mm for detectors using ionization.

The ratio of the smoke response threshold values ymax : ymin or mmax : mmin shall not be greater than 1.6.

The lower response threshold value ymin shall be not less than 0.2, or mmin shall not be less than 0.05 dB m-¹.

Repeatability of CO response

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

The CO response threshold value of the specimen to be tested shall be measured as described in 5.1.6 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 CO response threshold value shall be designated c_max, the minimum value shall be designated c_min.

The ratio of the CO response threshold values c_max : c_min shall be not greater than 1.6. The minimum CO response threshold value c_min shall be not less than 30 ppm

Directional dependence of smoke response 5.4.1 Object

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

The smoke 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 smoke response threshold value shall be designated m_max, or y_max and the minimum smoke response threshold value shall be designated m_min, or y_mm

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

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

The ratio of the smoke response threshold values ymax : ymin or mmax : mmin shall not be greater than 1.6.

The lower response threshold value ymin shall be not less than 0.2, or mmin shall not be less than 0.05 dB m-¹.

Directional dependence of CO response

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

The CO response threshold value of the specimen to be tested shall be measured eight times as described in 5.1.6, 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 c_max , the minimum value shall be designated c_min .

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 value was measured is referred to as the least sensitive orientation, and the orientation for which the minimum value was measured is referred to as the most sensitive orientation.

The ratio of the CO response threshold values c_max : c_min shall not be greater than 1.6. The minimum 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 5.1.7 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 t_max , the minimum value shall be designated t_min .

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 t_max ; t_min shall not be greater than 1.6.

Lower limit of heat sensitivity

To confirm that detectors are not more sensitive to heat alone, without the presence of smoke and/or CO, than is allowed in EN54-5.

The specimen shall be tested, in its most sensitive orientation, using the methods described in 5.3 and 5.4 of EN54-5, but with the test being terminated when an air temperature of 55°C has been reached For the purposes of these tests, the test parameters for Class A1 detectors shall be used.

In the test for static response temperature, the specimen shall not give an alarm signal at a temperature less than 54°C.

The specimen shall not give an alarm signal at any rate of rise of air temperature in a time less than the lower response time limits specified in Table 4 of EN54-5 for a Class A1 detector.

Reproducibility of smoke response

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

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

The mean of these smoke response threshold values shall be calculated and shall be designated y or m .

The maximum smoke response threshold value shall be designated m_max, or y_max and the minimum smoke response threshold value shall be designated m_min, or y_mm

The ratio of the response threshold values y_max : y or m_max : m shall not be greater than 1.33, and the ratio of the response threshold values y : y_min or m : m_min shall not be greater than 1.5.

The lower response threshold value y_min shall not be less than 0.2 or m_min shall not be less than 0.05 dB m^-1.

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 5.1.6.

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

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

The ratio of the CO response threshold values c_max : c shall not be greater than 1.33, and the ratio of the CO response threshold values c : c_min shall not be greater than 1.5. The minimum CO response threshold value cmin shall not be less than 30 ppm.

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 5.1.7 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 t_max and the minimum value shall be designated t_min.

The ratio of the heat response values t_max;t_min shall not be greater than 1.6.

Long term stability of CO response

To confirm that the CO response of the detector is stable over long periods of time.

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 5.1.6, 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 c_max. Designate the lowest of the values measured in this test and that measured for the same detector in the reproducibility test as c_min.

The detector shall emit neither alarm nor fault signals during the test when in air free of CO.

The ratio of the CO response threshold values c_max ; c_min shall not be greater than 1.6. The minimum CO response threshold value c_min shall not be less than 30 ppm.

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 smoke 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 smoke response threshold value shall be designated m_max, or y_max and the minimum smoke response threshold value shall be designated m_min, or y_mm

The CO response threshold value of the specimen shall be measured as described in 5.1.6, 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 c_min .

For detectors incorporating heat sensors, the heat response value shall be measured as described in 5.1.7 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 t_max, and the minimum shall be designated t_min.

The ratio of the smoke response threshold values ymax : ymin or mmax : mmin shall not be greater than 1.6.

The lower response threshold value ymin shall be not less than 0.2, or mmin shall not be less than 0.05 dB

Air movement

To show that the smoke sensitivity and the CO sensitivity of the detector are not unduly affected by the rate of the airflow.

The smoke 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 y(0.2)max and y(0.2)min or m^max and rn^min.

These measurements shall then be repeated but with an air velocity, in the proximity of the detector, of (1 ± 0.2) m s^-1. The response threshold values in these tests shall be designated y(1.0)max and y(1.0)min or m^max and m^min.

Additionally, for detectors using ionization, the specimen to be tested shall be subjected, in its most sensitive orientation, to an aerosol-free air flow at a velocity of (5 ± 0.5) m s^-1 for a period of not less than 5 min and not more that 7 min, and then at least 10 min later, to a gust at a velocity of (10 ± 1) m s^-1 for a period of not less than 2 s and not more than 4 s. The specimen shall be monitored during the exposure to aerosol-free air to detect any alarm or fault signals.

Dry heat (operational)

The specimen to be tested shall be installed in the smoke tunnel described in annex A of EN54-7, 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 smoke tunnel shall then be increased to (55 ± 2) °C, at a rate not exceeding 1 K min^-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 (55 ± 2) °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 y_max or m_max, and the lesser shall be designated ymin or mmin.

The specimen to be tested shall then 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.

Cold (operational) smoke

To demonstrate the ability of the smoke sensor to function correctly at low ambient temperatures appropriate to the anticipated service environment.

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 y_max or m_max, and the lesser shall be designated ymin or mmin.

No alarm or fault signal shall be given during the transition to the conditioning temperature or during the period at the conditioning temperature.

The ratio of the response threshold values ymax : ymin or mmax : mmin shall not be greater than 1.6.

Cold (operational) CO

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 K min^-1, and maintained at this temperature for 2 h.

The CO response threshold value shall then be measured as described in 5.1.6 but with the temperature at (-10 ± 3) °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 c_max , and the lesser shall be designated c_min .

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 c_max ; c_min shall not be greater than 1.6.

Damp heat, cyclic (operational) 5.18.1 Object

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

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 electrochemical cell electrolyte etc.).

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). 5.21

Sulphur dioxide SO2 corrosion (endurance)

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

Shock (operational)

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

Vibration, sinusoidal, (operational)

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

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.