SST F120 - Required Quantity of Flame Detectors; Avoiding Sources of False Alarms

January, 2016 120-17
Model F120 UV/IR Flame Detector
Required Quantity of Flame Detectors
The F120 has a cone of vision of 90° and a coverage area of 70 feet within its center axis.
Your specic application will determine the number of ame detectors required to protect an
area or monitor an area or equipment. The size of the re determines the ame detector’s
sensitivity and detection range.
At a minimum, one ame detector may provide adequate protection to monitor for presence of
re. However, any obstruction, size of the protected area, and size of the equipment should
be taken into consideration.
A ame detector located on the top of the equipment (looking down) may provide adequate
coverage as long as the entire unit is within its eld of view. However, in areas with high
ceilings, placing a ame detector directly on the ceiling may not be ideal. A ame detector
installed monitoring just one side of the equipment may not provide adequate coverage as
the detector’s eld of view may be obstructed by the equipment itself. The detector may not
see a re that starts on the other side of the equipment until it has grown in size. Therefore
a secondary detector must be installed on the exact opposite of the rst detector to provide
adequate coverage.
For applications which requires protecting an enclosed area such as a room, a minimum of
4 ame detectors should be considered located at each corner of the enclosed area with
a maximum of 70 feet (21 m) on each side angled at 45 degrees. This conguration will
provide coverage on all sides from the top of the ceiling, down to the walls, and the oor of the
enclosure. Additional detectors should be utilized if the eld of view of any of the detectors
are obstructed by equipment, windows, post, or wall.
Avoiding Sources of False Alarms
Vibration
Mounting location should be as free from shock and vibration as possible. Due to the high
sensitivity of the ame detector, it must be mounted to a rigid, stable support where no vibration
is present. Just a very slight movement of the ame detector when viewing an object that
is 70 feet (21 m) away can produce a considerable variation in the radiation signature being
received. Outdoors, avoid mounting the ame detector on a light pole whenever possible.
But if this is not possible, be sure that the pole is rigid enough that there will be no vibration
when a vehicle drives by. This is also applicable in areas near train tracks.
When monitoring machinery such as a motor or turbine, mount the ame detector to stable
supports that will not transmit the vibrations generated by the machines.
When mounted on the end of a conduit run, be sure to provide support to the conduit near
the ame detector.
Oceans, Lakes, Rivers, and Water Puddles
A combination of reected sunlight and puddle of water with wind blowing across it creating
ripples in the water surface can produce varying amounts of UV or IR radiation which the ame
detector will interpret as a possible ame. Likewise, natural waves in ocean water or waves
produced by movement of a boat in a lake or river can produce a similar effect if there is a
nearby source of radiation. Reposition or reorient the detector such that any areas where
water can accumulate will not be visible.