Optimize Performance New Flame Scanner FIREYE 45UV5-1101 for Industrial Machinery .

The FIREYE 45UV5-1101 is a self-checking ultraviolet (UV) flame scanner designed for industrial burners where safety, reliability, and hazardous-area compliance are critical. It detects UV radiation from gas and light oil flames and provides a fast, reliable flame signal to compatible FIREYE burner management systems. With a 1-inch BSP mounting thread, 50 Hz operation, and explosion-proof housing options, the 45UV5-1101 is widely used on process heaters, industrial boilers, and multi-burner installations that must run continuously with minimal downtime. 

Main Technical Data for FIREYE 45UV5-1101

How the FIREYE 45UV5-1101 Detects Flame

Inside the 45UV5-1101 is a UV Geiger-Muller lamp, a gas-filled detector that responds only to short-wave ultraviolet radiation emitted by combustion flames. When UV photons in the 190–270 nm band strike the detector, the gas ionizes and produces short, high-amplitude current pulses. The rate of these pulses is proportional to flame intensity: a strong, stable flame generates a high pulse frequency, while a weak or unstable flame generates fewer pulses. When the flame disappears, the pulses stop almost immediately. 

Unlike visible-light or infrared sensors, this UV tube is “solar-blind”; it is essentially insensitive to visible light and most background IR radiation. This allows the 45UV5-1101 to ignore hot refractory, glowing metal, and ambient lighting, focusing only on the UV signature of the flame. The result is highly selective flame detection that reduces nuisance trips and false “flame on” indications in complex furnaces.

The scanner’s pulse output is routed to a FIREYE amplifier such as the 25SU3 or 25SU5. The amplifier counts the pulses, interprets them as a flame signal, and drives its flame relay accordingly. If the pulse rate drops below a defined level, the amplifier recognizes loss of flame and initiates a safe shutdown sequence. 

Self-Checking Operation for Continuous Firing

One of the defining characteristics of the 45UV5-1101 is its self-checking capability. In many process plants, burners operate for weeks or months without planned shutdowns. A conventional, non-self-checking scanner could fail “blind” during this time, leaving the control system unable to recognise that the detector is no longer functioning. To avoid that risk, the 45UV5-1101 incorporates an electromagnetic shutter inside the scanner housing. 

At regular intervals, the shutter closes briefly, blocking the UV light path to the detector. During this closed interval, the amplifier expects the flame signal to fall to zero. When the shutter reopens, the flame signal must reappear. The amplifier monitors this pattern continuously:

• If the flame signal persists when the shutter is closed, the system suspects a scanner fault or wiring short.

• If the signal does not return when the shutter opens, a detector or circuit failure is indicated.

• Any abnormal behavior during the self-check cycle can drive the system to lockout, preventing continued operation on a false flame indication.

This built-in self-test makes the 45UV5-1101 especially suitable for continuous-duty burners, large process heaters, and multi-burner installations where regular manual scanner testing would be impractical.

Explosion-Proof and Industrial-Grade Mechanics

The 45UV5-1101 is available in explosion-proof, hazardous-area housings such as the 45UV5-1101EX and 45UV5-1101CEX assemblies. These versions integrate the scanner into certified enclosures rated Exd II C T6 with IP66 protection, providing both gas-group coverage and dust-tight performance. This allows the scanner to be installed in classified zones where flammable gases, vapors, or dusts may be present. 

Key mechanical design features include:

• Rugged cast housing – Designed to withstand vibration, temperature variations, and rough industrial handling.

• Sealed cable entries – Threaded openings for compression-style glands maintain the explosion-proof integrity while providing a secure cable termination. 

• Dedicated purge connection – A 3/8" NPT tapping allows purge air to be introduced across the lens, helping to keep the optical surface clear of soot, ash, and oil mists. 

• 1" BSP sight connection – The front of the scanner mounts directly to a 1" BSP sight pipe, giving a stable, repeatable flame view and simplifying burner-front design. 

These mechanical characteristics mean the 45UV5-1101 can be installed close to the burner in tough environments—typical for refineries, petrochemical plants, and heavy industry—while still maintaining long service life.

Suitable Fuels and Applications

The spectral response of the 45UV5-1101 is optimized for clean gaseous and light oil flames. Typical fuels include natural gas, methane-rich process gases, coke-oven gas, propane, butane, and light petroleum distillates such as kerosene and light fuel oil. For these fuels, the UV output is strong, and the scanner can easily distinguish flame from background conditions. 

Common application areas:

• Package boilers and field-erected industrial boilers

• Process heaters and direct-fired furnaces in refining and petrochemicals

• Thermal fluid heaters and air heaters

• Multi-burner systems where each burner requires its own dedicated, supervised flame scanner

For heavy oils, pulverized coal, or fuels with high levels of soot and ash, infrared (IR) scanners are often preferred. However, the 45UV5-1101’s sensitivity to UV-absorbing substances such as ash, unburned oil droplets, water, and steam also makes it a useful diagnostic tool: loss of UV intensity can indicate deteriorating combustion quality or excessive contamination in the flame path. 

Integration with FIREYE Flame Safeguard Systems

The 45UV5-1101 is specifically intended for use with FIREYE self-checking amplifiers such as the 25SU3 and 25SU5, forming a complete flame safeguard channel:

• The scanner provides a pulsed UV signal plus shutter modulation.

• The amplifier interprets flame strength, validates the self-check pattern, and drives the flame relay.

• The burner management system uses the relay output to permit or block fuel flow, initiate ignition, and shut down on unsafe conditions. 

Because both scanner and amplifier come from the same platform, the electrical characteristics, self-check timing, and fault responses are tightly coordinated. This simplifies commissioning and ensures that the overall system behavior meets modern burner safety codes.

Installation and Engineering Considerations

To get a strong, stable signal from the FIREYE 45UV5-1101, engineering and installation should follow a few best practices:

1. Sight line
   Aim the scanner so that it views the main combustion zone of the burner, not the igniter or refractory wall. A slight angle across the flame often gives better discrimination than looking straight down the burner throat.

2. Sight pipe design
   Use a rigid, properly supported sight pipe with internal diameter and length recommended in the FIREYE documentation. The pipe should be insulated or cooled as necessary to keep the scanner within its allowable ambient temperature range.

3. Purge air
   Provide a clean, dry purge air supply where contamination is likely. Stable, low-pressure purge flow across the lens helps maintain a clear optical path and extends maintenance intervals.

4. Cable routing
   Use suitable flame-rated or armoured cables and appropriate glands for the hazardous-area rating. Keep scanner signal cables away from heavy power conductors to minimise electrical noise.

Why Choose the FIREYE 45UV5-1101

For plants that run continuously and operate in hazardous areas, the FIREYE 45UV5-1101 brings together several crucial advantages:

• Self-checking UV technology designed for long firing cycles

• Strong discrimination between genuine flame UV and background light

• Certified explosion-proof housings for classified zones

• Compatibility with proven FIREYE burner management platforms

• Rugged mechanical construction, suitable for real-world burner fronts

In short, the FIREYE 45UV5-1101 is not just a UV detector; it is a fully supervised, hazardous-area-ready flame scanner intended to keep industrial combustion systems safe, reliable, and efficient throughout their operating life.