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
).
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 Detector must be positioned in roof apex
0
5
10
15
20
25
30
35
0
5
10
15
20
25
Width of Room in metres
Angle of Pitch
in degrees
Limit
Detector must be positioned in apex
Roof can be defined as flat
Χ
Slope if
Χ
≥
0.6 Metres
Υ
Υ
Υ
(max) = 7.5 + (7.5 x
Φ
/100)
Fig. 1.
Fig. 2.
Φ
