Siemens Combustion QRA4.U Flame Detector

The Siemens Combustion QRA4.U Flame Detector is a industrial-grade UV flame detection sensor designed for the continuous supervision of gas and oil flames. Specifically engineered for intermittent operation, this detector is a standard for technicians working with high-demand industrial burners and commercial boiler systems. It features a high-sensitivity UV cell capable of detecting radiation in the 190 to 270 nm spectral range, ensuring it remains insensitive to infrared radiation, daylight, or the glow of hot firebrick.

Housed in a rugged aluminum casing with a 3/4"-14NPSM connecting thread, the QRA4.U is built for direct mounting on the burner or boiler front. This Siemens UV detector is fully compatible with a wide range of Siemens flame safe-guard controls, including the LFL, LME, LMV2, LMV3, and LMV5 series. With a 1.8-meter lead length and a 1/2"-14NPSM thread for conduit protection, it provides the flexibility required for complex control cabinet integrations. For precise commissioning, technicians should verify flame signal strength via microammeter, targeting the current levels specified in the respective burner control's data sheet.

Key Benefits for Contractors

• Enhanced Spectral Selectivity: Detects 190–270 nm UV radiation, effectively eliminating false triggers from glowing refractory or ambient light.
• Broad Control Compatibility: Seamlessly integrates with Siemens burner controls such as the LMV series and LFL systems for reliable flame proving.
• Rugged Industrial Design: Features an IP54-rated aluminum housing and a maximum combustion chamber pressure rating of 150 mbar.
• Precision Ignition Proving: Specifically tuned for ignition spark proving and the supervision of both yellow and blue-burning oil flames.
• Simplified Installation: Standard 3/4" NPSM mounting and 1.8m factory-installed wiring reduce field labor and configuration errors.

Common Questions

Is the QRA4.U compatible with continuous operation (24/7) burners?
No, the QRA4.U is designed for intermittent operation, meaning the burner must cycle at least once every 24 hours. For continuous operation systems, a self-checking UV detector (such as the QRA7 series) is typically required.

Can the internal UV cell be replaced if it fails?
The UV cell in the QRA4.U is encapsulated within the housing. When the cell reaches the end of its typical 10,000-hour service life, the entire detector unit must be replaced to ensure system integrity and safety.

How do I prevent false flame signals during the ignition phase?
To prevent interference, ensure the UV flame detector is mounted in a position where it cannot directly "see" the ignition spark, or verify that the burner control is configured to ignore the signal during the specific ignition timing sequence.

Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.