A flame sensor is an important safety device used to detect flames within a combustion appliance. These can commonly be found within marine boilers, oil burners, incinerators and other fuel burning devices. The main purpose of a flame sensor is to ensure that combustion is taking place correctly and reduces the risk of unsafe conditions occurring.
Flame detection is an important part of safe operations onboard ships, as fuel oil is used within boilers and other combustion appliances. This can pose a serious risk if not burnt correctly within the combustion chamber. A flame sensor will be used alongside the burner control system to detect the flame.
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A flame sensor detects a flame by sensing the radiation given off. Depending on the sensor type, it will detect either ultraviolet (UV), infrared (IR) or visible light. The sensor will send a signal to the burner management or flame safeguard system, which will then determine whether there is a flame present and if the burner can continue to operate safely. If the flame goes out whilst fuel is being supplied to the burner, the control system triggered by the flame goes out will trigger the correct safety sequence. This will usually involve shutting off the fuel supply.
However, the principle will usually be:
This sensor detects ultraviolet radiation that is being emitted from the flame. These are commonly used in industrial and marine applications where the detector needs to differentiate between the flame and other light sources. Usually, UV detectors will only detect certain wavelengths of radiation from the flame. This depends on the design of the detector, type of fuel that is being burnt and how it has been installed.
This detects infrared radiation from the combustion. Some detectors will analyse the variation in intensity or flicker of the flame to help differentiate it.Â
These can be used within the correct industrial applications. This depends on the detection range needed and burner design.
This detects the visible light being emitted from the flame. Whilst these can be used in some flame detection applications, they are often more prone to interference from external light sources than specialised UV or IR flame detectors. The correct type depends on the type of combustion appliance, conditions and manufacturers requirements.
Marine Boilers: Flame sensors are used to monitor the flame within the burner. If the flame goes out, the burner safety will shut off the fuel supply to prevent accumulation of unburnt fuel.
Sometimes flame sensors can fail to detect a flame or give an unreliable signal. Common issues include:
Always refer to the manufacturers manual and vessel safety procedures when troubleshooting issues. Never bypass a flame sensor to allow a burner to continue.
A regular inspection and maintenance of the flame sensor will ensure reliable detection.
A flame sensor is an important safety device within marine combustion appliances. It detects the radiation from the flame and informs the burner control system. If the flame goes out, the system can shut off the fuel supply and trigger the correct safety action. Regular checks, correct positioning and testing of the sensor will ensure a reliable system and safe combustion onboard.
To detect a flame and send a signal to the burner safety.
The flame safeguard will detect a flame failure and will usually shut off the fuel supply via the safety shutoff valves. The correct alarm/shutdown will be triggered.
Common flame sensors include UV, IR and visible light. This depends on the burner and manufacturers requirements.
Yes, the dirt or soot on the lens of the detector can cause a weaker signal and indicate a flame failure.
No, you should never bypass a flame safeguard as this can cause a serious risk of fire/explosion. The issue should be investigated and rectified using the correct procedures.
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