Summary
BS 5839-5:1988, a part of the BS 5839 series, specifies requirements, test methods and performance criteria for fire detectors utilizing attenuation of an optical beam for the detection of smoke aerosols.
An optical beam detector may or may not include an external reflector but is distinct from a point detector in that there is no integral mechanical connection to define or adjust the optical path length. This specification covers beam detectors with separations between the opposed components of 1 m to 100 m and minimum separations not exceeding 10 m.
Beam detectors with a minimum separation between the components defining the optical path in excess of 10 m are not covered by this standard because the dimensions of the fire test room described in BS 5445-9 preclude subjecting such detectors to the fire sensitivity test.
Detectors that detect thermal turbulence within the optical beam as an adjunct to the detection of attenuation of an optical beam are covered although the thermal turbulence detection is not tested beyond ensuring that performance as an optical beam detector is not impaired.
Contents
Foreword
Section 1 - Scope, Definitions
Section 2 - Requirements
Section 3 - Tests
Appendix A - Determination of the response threshold value