Electrical considerations
The detector signals an alarm state by switching an alarm latch
on increasing the current drawn from the supply from 550 �A
to a maximum of about 75 mA. This fall in the impedance of the
detector is recognised by the control panel as an alarm signal.
The alarm current also illuminates the detectors integral LEDs. A
remote indicator connected between the L1 In terminal and the -R
terminal will have a voltage equal to the supply voltage less one
volt across it and so will illuminate.
To ensure correct operation of the detector the control panel must
be arranged to supply a maximum of 33 V dc and a minimum of
12 V dc in normal operation.
The supply may fall to 6 V dc in alarm conditions if a supply current
of at least 10 mA is available at this voltage.
To ensure effective illumination of the integral LEDs and any
remote indicator, the supply to the detector should exceed 12 V.
To restore the detector to quiescent condition, ensuring all flames
are extinguished interrupt the supply to the detector for a minimum
of one second.
Note:
When using the detector the following must be avoided; outside
viewing, UV lamps, electrical sparking, welding and sources of
radiation, UV light sources, prolonged ambient temperatures above
60ºC and obstructions to the field of view.
Applications for UV flame detectors
UV flame detectors are designed for use in enclosed spaces and
require a clear line of sight within the area to be protected. They
are unaffected by draughts or convection currents.
They are fast acting and respond to a flame more than 25 m away
(refer to Figure 1).
Installation
If fitting to an XP95 Zone Monitor do not fir more than one device
per zone.
If fitting to a conventional control panel please verify the quantity
per zone with the panel manufacturer.
Marine Series 65 Base Mounted Flame Detectors
–90°
–75°
–60°
–45°
–30°
–15°
0°
15°
30°
45°
60°
75°
90°
0.1m² flame seen
at 25m in straight line
from flame detector
0.4m² flame seen
at 40m in straight line
from flame detector
0.1m² flame not seen
at 25m since it is not
in the field of view of
the flame detector
25m
0
40m
centre line of detector
detection of 0.4m² flame
detection of 0.1m² flame
Figure 1:
Field of view
The field of view of the flame detector is shown in Figure 1. This
also provides information on the size of fire that is detectable at
various distances.
Vertical Plane
Ceiling
5m
10m
15m
20m
Floor
Plan View
10m Dia.
20m Dia.
30m Dia.
40m Dia.
Heigh
t
Figure 2:
Ceiling mounting example
The flame detectors can also be ceiling mounted, positioned above
the anticipated flame source or at the centre of the area to be
protected, perpendicular to the floor below. If the detector cannot
see the whole of the area to be protected, one or more additional
detectors may be required. Refer to the angle of view diagram -
Figure 2 - to establish the detector performance. The area of
detection is dependent on the detectors height above the likely
source of flame. The detector has a 90º conical field of view or 45º
either side of the viewing axis centre line. The maximum ceiling
height is 20 m. If the detector is perpendicular to the floor and at
a height of 10 m then the detector will view a circular floor area
below with a 10 m radius - 20 m diameter circle.
