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5 Application Guidelines
In considering the application of the detector it is important to know of any conditions that may
prevent the detector from responding. The detector provides reliable response to hydrocarbon
flames within its field of view, and insensitivity to common false alarm sources. Solid obstructions or
a direct view of intense light sources may result in a reduction in the coverage and/or a reduction in
the detector sensitivity. Scaffolding or tarpaulins in the detector's field of view may reduce coverage.
Contamination of the detector window may result in a reduction in sensitivity.
The detector has a 90° conical field of view. The location and orientation of the detector in relation
to the protected area determines the actual footprint. Achieving the desired coverage depends on
congestion within the protected space, the location of the detector(s) and the distance of the
detector from the hazard. It may be necessary to install more than one detector within an area to
achieve adequate coverage.
The detector sensitivity, expressed as fire size at a distance, is determined by the radiant heat
output of the fire. This is a function of the fuel source, how it is released and distance from the
detector to the fire.
In common with other forms of flame detection the detector's sensitivity is reduced and potentially
blinded by dense obscurants such as smoke, fog, and other airborne particulates. The detector is
insensitive to arc welding; however, this should not be conducted within 32 ft (10 m) of the detector.
Positioning Requirements
The following guidelines have been based on operational feedback, reflecting commonly
experienced problems which can be traced to a failure to observe the following:
Ensure the mounting position is free from vibration or movement.
•
Prevent accidental knocking or forcing out of alignment.
•
Isolate as far as possible from local electrical interference sources.
•
Ensure sufficient detection to achieve adequate coverage for all likely hazards.
•
Minimize exposure to contamination of the detector face plate.
•
Ensure ease of maintenance access to detector (i.e., direct ladder or scaffold access).
•
•
Do not allow the VSF303 to have direct view of hot surfaces.
•
Ensure that the VSF303 has no direct view or reflected view of a friendly fire.
•
The detector should be aimed downward by at least 10° to 20°.
All these issues are of crucial importance to a successful installation and they should be afforded
great attention during the detailed design, construction, and commissioning phases of the work.
Detection Coverage
Detector locations can be chosen from computer models or from site surveys. The detectors should
be aligned to view the intended hazard considering any obstruction and congestion. Software
analysis of the actual detector coverage may be required to ensure adequate coverage of the
hazards. This analysis can also be used to optimize the number of detectors and the loop
configuration. The cones of vision are detailed in Appendix B.
Exposure to Flare Radiation
Flame detectors are frequently used where hydrocarbon fire hazards are expected; these are quite
often processing plants where a flare stack is in use nearby. The detector shall not have a direct
view of the flare or a reflected view of the flare.
This document is strictly private and confidential, reproduction without Viking Corporation approval is prohibited. © 2021 The Viking Group Inc.
VSF303 Flame Detector
Safety and Technical Manual
Form No. F_020521
Rev: 2
17
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