22318.37.01 15.09.05
3
Typical Minimum Beam Spacing
Beam Distance
Beam Spacing
Beam Distance
Beam Spacing
10 0.87m 60 5.25m
20 1.75m 70 6.12m
30 2.62m 80 7.00m
40 3.50m 90 7.87m
50 4.37m 100 8.75m
In all installations the latest national fire standards
must
be consulted. If there is any doubt on the correct
mounting height, positioning may be determined by smoke tests.
3.1. Detector Positioning In Apex Of Sloping Ceiling.
A ceiling is defined as sloping if the distance from the top of the apex to the intersection of the ceiling and
adjacent wall is greater than 0.6 metres. See Fig. 1.
When a Detector is positioned in the apex of a ceiling (See Fig. 2), the lateral beam distance covered (
Υ
) can
be increased in relation to the angle of pitch (
Φ
), up to a maximum of 25%.
For Example:
If the pitch angle is 20 degrees, the lateral coverage can be increased from 7.5 metres either side of the beam
(
Υ
) to:
Υ
= 7.5 + (7.5 x 20/100) metres
Υ
= 9 metres
Therefore, with a roof pitch of 20 degrees the lateral coverage can be increased from 7.5 metres either side of
the beam to 9 metres either side of the beam, but only for the beam positioned in the apex. All other
calculations remain the same.
Limit to when a beam detector must be positioned in
roof apex
0.0
5.0
10.0
15.0
20.0
25.0
30.0
35.0
0
5
10
15
20
25
Width of Room in metres
Angle of
Pitch
in degrees
Roof can be defined as flat
Beam detector must be positioned in apex
Χ
Slope if
Χ
≥
0.6 Metres
Υ
Υ
Υ
(max) = 7.5 + (7.5 x
Φ
/100)
Fig. 1.
Fig. 2.
Φ
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