AS 7240.27:2018 pdf download.Fire detection and fire alarm systems Part 27: Point type fire detectors using a smoke sensor in combination with a carbon monoxide sensor and, optionally, one or more heat sensors (ISO 7240-27:2018, MOD).
4 General requirements
4.1 Compliance In order to comply with this document, the detector shall meet the requirements of: Clause 4, 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. 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 5.31.
4.3 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, 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. 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 — 5° from the axis of the detector in any direction; — 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 (e.g. 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 equipment (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.
4.7 On-site adjustment of response behaviour If there is provision for on-site adjustment of the response behaviour of the detector then: a) for all of the settings, at which the manufacturer claims compliance with this document, the detector shall comply with the requirements of this document and access to the adjustment means shall be possible only by the use of a code or special tool or by removing the detector from its base or mounting;b) any setting(s) at which the manufacturer does not claim compliance with this document shall be accessible only 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 this document.
These adjustments may be carried out at the detector or at the control and indicating equipment.
4.8 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 sensing chamber of the detector, where such an ingress could affect its sensitivity. NOTE This requirement is intended to restrict the access of insects into the sensitive parts of the detector. it is known that this requirement is not sufficient to prevent the access of all insects, however it is considered that extreme restrictions on the size of access holes can introduce the danger of clogging by dust, etc. It could therefore be necessary to take other precautions against false alarms due to the entry of small insects.
4.9 Rate-sensitive CO response behaviour The response threshold value of the detector can 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 concentrations and those generated bya fire. If such rate-sensitive behaviour is included, then it shall not lead to a significant reduction in the sensitivity of the detector to fires, nor shall it lead to a significant increase in the probability of unwanted alarms.AS 7240.27 pdf free download.