ISO 7240-27:2018 pdf free
ISO 7240-27:2018 pdf free.Fire detection and alarm systems
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.
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.
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 by a 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.ISO 7240-27 pdf download.
