IR-S Infrared Flame Detector

Control Systems


Due to the diversification of boiler fuels and low NOx (nitrogen oxide) operation in recent years, it has become difficult to monitor burner flames using conventional ultraviolet and infrared detection methods.

To adapt to this changing business environment, Mitsubishi Power has improved upon conventional IR flame detectors and commercialized the IR-S Infrared Flame Detector, a new type of flame detector with excellent detection reliability, maintainability and cost performance.

An IR-S type infrared flame detector uses a light guide (optical fiber) to guide the light from the flame to an infrared sensor (semiconductor device). The "average value" and "variance" of the intensity of the infrared light are detected so that the infrared light intensity from the burner flame and that from the heated furnace wall are differentiated. Consequently, the variance of the flame in the burned zone in the burner is detected.

This results in dramatic improvements to detection sensitivity and dynamic range in low-luminance conditions, and allows the detector to support various fuels including gas, fuel oil and coal.

The IR-S Infrared Flame Detector employs a newly-developed sensor circuit to achieve reliable boiler flame monitoring.


If you replace a conventional flame detector with this new type, the pre-existing equipment can be reused.

Equipment Name Existing Methods of Flame Detection
UV Type IR Type
Sensor Unit Replaced Replaced
Flame Detector Panel Replaced Replaced
Sensor Cable Reused Replaced
Guide Pipe Reused Reused
Cooling-air Piping Reused Reused
Cooling Fan Reused Reused


High Sensitivity Design

The newly designed sensor circuit enables stable detection of the burner flame. The flame is detected through the unlit zone.

Extended Detection Range

The sensor has 100 times the dynamic range of a conventional product and allows stable detection from slow combustion to a high intensity flame. No sensitivity adjustment is required for the sensor at the site.

Maintenance Free

A ball lens is used to eliminate the need to clean the sensor window.

Long-life Sensor

Because a long-life infrared semiconductor sensor element is used, periodic replacement is not necessary.

Decreasing the Number of Panels

The detector unit is compact with a space-saving design which allows one panel to incorporate 40 corners.

Reuse of Existing Boiler Facilities

When you replace a flame detector, work is not necessary for the boiler itself.

Reuse of Cable

Changing the cable between the sensor and the panel is not necessary. (When the existing system uses UV-type detection)

System Configuration

Flame Detector Panel


Flame Detector Panel


Flame Detector Unit

Flame Detector Main Unit


Flame Detector Main Unit


Cross Sectional View of Sensor Head

For Fuel Oil Burner

The following example applies to a fuel oil burner.



Sensor Unit

The specifications of the sensor unit are as follows.

Series Explosion-proof (Exd II BT4), waterproof
Dimensions Entire Length Optional
Guide Pipe 50A (40A)
Detection Wavelength 500 - 1,100nm
Allowable Temperature Detector Head Component Not exceeding 200℃
Cooling Air Temperature Not exceeding 60℃
Air Pressure In-furnace pressure +1.5kPa or greater
Air Flow At least 1.0Nm3/min per sensor
(fan capacity should be designed at 1.5Nm3/min per sensor to account for when withdrawn inspection takes place)

Flame Detector Panel

The specifications of the flame detector panel are as follows.

Series Closed indoor self-standing type, with access hatches on front and back
Dimensions 2,300mm (H) ×810mm (W) ×800mm (D)
  • Flame Detector Unit
  • Redundant Power Supply Units
  • Terminal Unit
Output Signals Flame on 1a
Low luminance level 1a
Power loss 1b
Contact capacity AC/DC 48V, 1.25A
Ambient Temperature 0 to 50℃