Net Safety Monitoring
MAN-0015 Rev 14 UVIRS-A/AR
7
November 07, 2008
Field of View
(as per FM and NFPA definition)
The area in front of a flame detector, where a standardized flame can be
detected and which is specified by distance and angle off the central axis, is
the Field of View. The referenced flame is moved to 50% of the maximum
on-axis detection distance and then moved off-axis horizontally and
vertically to the limit of detection. These off-axis angle limits specify Field
of View.
Table 2: Field of View Testing
Field of View Testing
Fuel Size
Horizontal
Degrees
Vertical
Degrees
n-Heptane
1' x 1'
120 (+60, -60)
120 (+60, -60)
Methanol
1' x 1'
120 (+60, -60)
105 (+45, -60)
Methane
36" Plume
120 (+60, -60)
95 (+35, -60)
Propane
16" Plume
110 (+55, -55)
95 (+35, -60)
Jet Fuel
1' x 1'
120 (+60, -60)
95 (+35, -60)
Diesel
1' x 1'
120 (+60, -60)
95 (+35, -60)
Lube Oil
1' x 1'
120 (+60, -60)
95 (+35, -60)
Ethanol
1' x 1'
120 (+60, -60)
100 (+40, -60)
Gasoline
1' x 1'
120 (+60, -60)
95 (+35, -60)
NOTE: Data based on Maximum Sensitivity Setting.
Installation Considerations
The following should be considered when mounting flame detectors.
•
Point detector toward where the flame is expected.
•
Ensure an unobstructed view of the area to be monitored.
•
Employ more than one detector to ensure the hazard is fully covered.
•
Mount the detector a few feet (about 1 metre) below the ceiling so it can
respond before being blocked by smoke accumulation at the ceiling.
•
If dense smoke is likely to accumulate prior to flame (as in an electrical
fire), supplement UV/IR detector(s) with other protection such as Net
Safety Monitoring Airborne Particle Monitor.
•
The detector should be accessible for cleaning the window/lens
and
reflector surfaces.
•
Tilt detector downward a minimum of 10 to 20
°
to reduce dirt and dust
accumulation which could obscure the detector’s viewing window.
•
Securely mount detector so as to reduce vibration as much as possible.
•
When located outside, detector sensitivity can be reduced by heavy fog,
rain and/or ice.
•
Consider shortening the time delay settings when smoke is expected to
accumulate before or during a fire (refer to "System Sensitivity").
•
Reduce sensitivity setting if false alarms, related to surrounding activities,
occur (refer to "System Sensitivity" )
•
When installed near or on water (such as an off shore platform), be sure to
take into account the low horizon level when tilting detector downward.
•
UV radiation, other than that produced by an actual fire, is referred to as
"background UV". An example of a high level of background UV could
be a flare stack situated outside of a building. The UV radiation produced
by this flare, in conjunction with a false alarm IR source, may be
