Reaffirmed 2018

NATIONAL FOREWORD

This Indian Standard (Part 7) which is identical with ISO 7240-7 : 2011 ‘Fire detection and alarm systems — Part 7: Point-type smoke detectors using scattered light, transmitted light or ionization’ issued by the International Organization for Standardization (ISO) was adopted by the Bureau of Indian Standards on the recommendation of the Fire Fighting Sectional Committee and approval of the Civil Engineering Division Council.

This standard is published in various parts. Other parts in this series are:

Part 5 Point-type heat detectors

Part 11 Manual call points

Part 15 Point type fire detectors using scattered light, transmitted light or ionization sensors in combination with a heat sensor

A fire detection and alarm system is required to function satisfactorily not only in the event of a fire but also during and after exposure to conditions likely to be met in practice, such as, corrosion, vibration, direct impact, indirect shock and electromagnetic interference. Specific tests are intended to assess the performance of the smoke detectors under such conditions.

This standard is not intended to place any other restrictions on the design and construction of such detectors.

This standard introduces a requirement that smoke detectors that operate on the scattered or transmitted light principle be marked with one of two possible nominal response threshold value bands. This marking provides for a clearer choice of response values so that the risk of unwanted alarms can be decreased in installations where unfavourable environmental conditions are present.

NOTE — For some test fires, smoke detectors that operate on the scattered or transmitted light principle and that have been factory set to the upper response threshold value band can fall outside one of the classification limits given in ISO/TS 7240-9 : 2012.

This standard also introduces additional requirements for smoke detectors with more than one smoke sensor.

The text of ISO Standard has been approved as suitable for publication as an Indian Standard without deviations. Certain conventions are, however, not identical to those used in Indian Standards. Attention is particularly drawn to the following:

a) Wherever the words ‘International Standard’ appear referring to this standard, they should be read as ‘Indian Standard’.

b) Comma (,) has been used as a decimal marker while in Indian Standards, the current practice is to use a point (.) as the decimal marker.