Selecting a Flame Detector
Planning and installing flame detectors requires consideration of the nature of the fire, the protected area, environmental conditions, detector capabilities and limitations and user expectations. For instance, is it more important to select a detector that alarms a few seconds faster or a detector that has superior immunity to false alarms? Is it more important that the detector can detect a wide range of fuels or shall it focus on only one fuel?
Defining the application:
You need to consider the following:
- All fuels that present a fire hazard
- Location of potential fires
- Minimum fire sizes to be detected
- Maximum detection distance required
- Speed of response
- All sources of nuisance radiation
- Environment conditions
Fuel types
You will need to know the following:
- Hydrocarbon or non-organic fuel types (i.e. Methane vs. Hydrogen or Silane)
- Liquid or gases fuel source (flame detectors can detect liquid fires at a greater distance)
- Potential sources of false alarms (welding operations, reflected sunlight, extreme weather, etc depending upon type of flame detector)
Fire Size
- Detector sensitivity and range are related to fire size. Performance is normally specified in relation to a standard 1 square foot gasoline pan fire for liquids, plume flame with 18" height and 8" width for gases, and defined by weight, size and pre-ignition configuration for solids
- Typical detection ranges based upon fire size are as follows:
| Fuel | Fire Size | UV | UV/IR | UV/IR/Vis | IR3 | IR single | Hydrogen |
| Gasoline | 1 sq ft pan fire | 50 ft | 50 ft | 80 ft | 200 ft | 50 ft | - |
| Heptane | 1 sq ft pan fire | 50 ft | 50 ft | 80 ft | 200 ft | 50 ft | - |
| JP5 | 1 sq ft pan fire | 37 ft | 37 ft | 150 ft | 37 ft | - | |
| Kerosene | 1 sq ft pan fire | 37 ft | 37 ft | 75 ft | 150 ft | 37 ft | - |
| Ethanol | 1 sq ft pan fire | 25 ft | 25 ft | 150 ft | 25 ft | 62 ft | |
| IPA | 1 sq ft pan fire | 25 ft | 25 ft | 150 ft | 25 ft | - | |
| Hydrogen | 18" Plume | 50 ft | 16 ft | 15 ft | - | - | 100 ft |
| Silane | 12" Plume | 30 ft | 15 ft | 50 ft | - | - | - |
Location of Flame Detector
- A flame detector is an optical device and thus it needs to have a clear view of the area to properly detect a fire.
- Flame detectors have a 3-D cone of vision ranging from 90 degrees for the 3500 series to 120 degrees for the 3100, 3200 and 3300 Series Flame Detectors
- Sensitivity diminishes at the edges of the cone of vision so their might be some blind spots at the edges. The detector would still respond but the fire would need to be larger, perhaps up to four times that needed at the center of the cone.
- Since both sensitivity and range are related to fire size, if the detector is placed further away from (or closer to) the fire source, the detectable fire size will vary according to the inverse square law. So doubling the detection distance results in only ¼ of the radiant energy reaching the detector, or conversely, for the same response time, the surface area of the fire then needs to be 4 times larger.
Selecting the Flame Detector
| Detector | Applications | Advantages |
| 3100 Series | Hydrocarbon fires, Hydrogen, Silane and other hydrogen based fuel fires Indoors or Outdoors |
Widest cone of vision in the industry Low false alarm rate Unaffected by solar radiation Multiple fuel types FM and CSFM approvals |
| 3200 Series | Semiconductor Wet Bench applications IPA and other semiconductor fuels Indoors |
Enclosure resistant to various semiconductor materials FM and CSFM approved |
| 3300 Series | Hydrocarbon fires, Hydrogen, Silane and other hydrogen based fuel fires Indoors |
Widest cone of vision in the industry Low false alarm rate Unaffected by solar radiation Multiple fuel types FM and CSFM approvals |
| 3300 Series - UV/IR | Hydrocarbon fires, Hydrogen, Silane and other hydrogen based fuel fires Indoors or Outdoors |
Moderate speed Moderate sensitivity Low false alarm rate Unaffected by solar radiation |
| 3500 Series - UV | Hydrocarbon fires, Hydrogen, Silane and other hydrogen based fuel fires Indoors or Outdoors |
High speed Moderate sensitivity Low Cost Unaffected by hot objects or solar radiation |
| 3500 Series - IR3 | Hydrocarbon Fires Indoors or Outdoors |
Moderate speed Highest sensitivity High immunity to false alarms Longer detection range Unaffected by solar radiation |
| 3500 Series - Single IR | Hydrocarbon fires Indoors |
Moderate speed Moderate sensitivity Low Cost |
| 3500 Series - Hydrogen | Hydrogen fires | Detects the Hydrogen invisible flames
Longer detection range High immunity to false alarms |