Fireye 85UVF1A-1QD Flame Detector

Sensing Element: The detector is equipped with a built-in UV photosensitive tube (ultraviolet phototube), which is sensitive to ultraviolet radiation in the wavelength range of 185-260nm (this band is a unique spectral feature during flame combustion, such as natural gas and fuel oil combustion, which will release such ultraviolet rays).

Optical Design: Focuses the flame ultraviolet rays through the front lens or window to avoid interference from ambient light (such as sunlight and incandescent lamps) (the wavelength of non-flame ultraviolet rays is usually not within this range).

Analog Signal Conversion: When the UV photosensitive tube receives ultraviolet light, it generates a weak current signal (proportional to the flame intensity), which is amplified by the internal operational amplifier of the detector and converted into a recognizable voltage signal.

Filtering and Noise Reduction: Non-ultraviolet frequency band interference signals (such as electromagnetic noise and visible light) are eliminated through a band-pass filter to ensure signal purity.

If the signal intensity exceeds the threshold, it is determined as "flame present", and a high-level signal (such as 24V DC) is output;

If the signal is lower than the threshold and lasts for a certain time (such as 0.5-1 second), it is determined as "flameout", triggering an alarm or interlocking protection.

Threshold Comparison: The processor compares the amplified voltage signal with the preset threshold:

Frequency Analysis (Optional Function): Some models analyze the flicker frequency of ultraviolet signals (there is a characteristic flicker frequency during flame combustion, such as natural gas flame about 5-50Hz) to further distinguish between real flames and interference sources (such as electric arc light, which is strong but has no fixed frequency).

When the flame is present, the relay closes, allowing the combustion system to continue running (such as keeping the fuel valve open);

When the flame is extinguished, the relay opens, Cut off the fuel supply in a coordinated manner，and sends an alarm signal to the DCS or PLC.

Relay Output: The detector has built-in relay contacts that switch on/off according to the flame status:

Signal Transmission: Transmits status signals (such as 4-20mA current signals and switch signals) to the control cabinet through cables to achieve remote monitoring.

Performs initialization self-inspection when starting up to confirm normal hardware;

Monitors signal stability in real time during operation. If sensor failure (such as photosensitive tube aging) or circuit abnormality is found, it alarms through indicators (such as LED) or outputs fault signals.

Built-in Self-Diagnosis Function: The detector regularly detects its own circuit, power supply, and sensing elements: