AS 7240.7 pdf download
AS 7240.7 pdf download.Fire detection and alarm systems
1 Scope
This document specifies requirements, test methods and performance criteria for point‑type smoke detectors that operate using scattered light, transmitted light or ionization, for use in fire detection and alarm systems installed in buildings (see ISO 7240‑1). This document also covers point‑type smoke detectors that incorporate more than one smoke sensor operating on these principles. Additional requirements and test methods for such detectors are given in Annex N. For the testing of other types of smoke detectors, or smoke detectors working on different principles, this document is only intended to be used for guidance. This document is not applicable to smoke detectors with special characteristics, developed for specific risks. NOTE Certain types of detectors contain radioactive materials.
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 7240‑1 and the following apply. ISO and IEC maintain terminological databases for use in standardization at the following addresses: — IEC Electropedia: available at http://www.electropedia.org/ — ISO Online browsing platform: available at https://www.iso.org/obp 3.1 aerosol density smoke density amount of particulates per volume as described operationally by one of two parameters: — m (3.3), an absorbance index, used in the testing of smoke detectors using scattered or transmitted light; — y (3.5), a dimensionless variable, used in the testing of smoke detectors using ionization Note 1 to entry: Note that these parameters are not concentrations sensu stricto, but represent values which are proportional to the concentration and have been shown to function in lieu of a true concentration value for the purposes of these tests. 3.2 least sensitive orientation point of rotation, relative to air flow, about the vertical axis where a detector produces the maximum response threshold value 3.3 absorbance index m measured light attenuation characterizing the concentration of particulates in smoke or an aerosol Note 1 to entry: The formula for m is given in Annex C. 3.4 closed detector optical or ionization smoke detector with the sensing volume(s) inside the enclosure Note 1 to entry: Smoke needs to enter the detector’s enclosure to be detected. 3.5 open detector optical smoke detector with the sensing volume(s) outside the enclosure Note 1 to entry: Smoke is detected outside the detector’s enclosure. 3.6 response threshold value A th <smoke detector> aerosol density in the proximity of the specimen at the moment that it generates an alarm signal, when tested as specified in 5.1.5 Note 1 to entry: The response threshold value may depend on signal processing in the detector and in the control and indicating equipment. 3.7 y dimensionless variable, reflecting the change in the current flowing in an ionization chamber as a known function of the concentration of particulates in the smoke or aerosol Note 1 to entry: The formula for y is given in Annex C.
4 General requirements
4.1 Compliance In order to comply with the provisions of this document, the detector shall meet the requirements of: a) Clause 4, which shall be verified by visual inspection or engineering assessment;b) the tests as described in Clause 5; c) Clauses 7 and 8, which shall be verified by visual inspection. 4.2 Response threshold value of detectors using scattered or transmitted light Detectors using scattered or transmitted light shall conform to one of the two response threshold value bands specified in Table 1 and the corresponding end‑of‑test conditions for the test fires specified in 5.19.4.3 Individual alarm indication Each detector shall be provided with an integral red visual indicator by which the individual detector releasing an alarm can be identified, until the alarm condition is reset. Where other conditions of the detector may be visually indicated, these 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. NOTE The alarm condition is reset manually at the control and indicating equipment (see ISO 7240‑2). The visual indicator shall be visible from a distance of 6 m in an ambient light intensity up to 500 lx at an angle of up to: a) 5° from the axis of the detector in any direction, and b) 45° from the axis of the detector in at least one direction. 4.4 Connection of ancillary devices The detector may provide for connections to ancillary devices (remote indicators, control relays, etc.), but open‑ or short‑circuit failures of these connections shall not prevent the correct operation of the detector. 4.5 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. 4.6 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.
