Saacke FLS09 UV-5 Flame Sensor 7-7955-10642723 R.2 IP65

Saacke FLS09 UV-5 Flame Sensor 7-7955-10642723 R.2 IP65

The Saacke FLS09 UV-5 Flame Sensor (Part Number: 7-7955-10642723, Revision R.2) is a high-performance optical flame monitoring device engineered specifically for heavy-duty industrial combustion systems and marine auxiliary/main boilers. Utilizing an ultra-violet (UV) phototube sensitive to short-wave radiation (typically 190–270 nm), this sensor provides instantaneous discrimination of hydrocarbon flame fronts against background refractory glow. Designed for continuous-duty operation under harsh marine engine-room environments, the unit features an IP65-rated ruggedized aluminum housing protecting internal optical and solid-state conditioning circuitry from moisture, oil mist, and saline atmospheres. 

Terminal Allocations & Input/Output Ratings

• Terminal 1 (L+ / Supply): +24V DC nominal input power supply from the Saacke burner management / flame amplifier card.
• Terminal 2 (GND / Common): System ground and reference shield terminal.
• Terminal 3 (Signal Out): Pulsed photoelectric output signal conveying flame flicker frequency to the burner control unit.
• Electrical Rating: Low-voltage solid-state output designed for direct interface with Saacke digital burner safety controllers. Maximum ripple voltage tolerance: < 10% of operational DC rail.

Compatible Equipment Models

• Compatible Burner Series: Saacke SKV, SSM, SSB, and DDZG rotary cup and pressure jet marine burners.
• Compatible Control Units: Saacke Burner Management Systems (BMS), Secon-series automation panels, and compatible Siemens/Landis flame amplifiers configured for UV sensor inputs.

Cross-Reference Part Numbers:

• Saacke MPN: 7-7955-10642723 / 7795510642723
• Assembly Revision: R.2 / Rev.2
• Alternative Industry Identifiers: FLS09-UV5, FLS-09 Ex Scanner variants.

Key Features

• High-speed UV spectrum photon detection ensuring burner trip times under < 1 second upon flame loss.
• Rugged IP65 weather-proof housing engineered to resist aggressive marine vibration and thermal shocks.
• Integrated optical lens fouling prevention via standard purge air connection interface.
• Precision-engineered solid-state internal electronics immune to ambient infrared (IR) boiler refractory radiation.
• Plug-and-play mechanical drop-in replacement for legacy FLS09 revisions without requiring wiring harness modifications.

Applications

• Marine auxiliary steam boilers and waste heat recovery units (WHRU).
• Marine propulsion boiler combustion management systems.
• Heavy industrial oil and gas-fired thermal fluid heaters.
• Power plant auxiliary boilers utilizing Saacke multi-fuel burners.
• Petrochemical refinery process flare and burner safety interlock loops.

Marine Engineer Expert’s Guide

• Optical Alignment & Siting: When mounting the FLS09 UV-5, ensure the sight tube is accurately pointed at the primary root zone of the flame (the intersection of fuel injection and air swirl). Misalignment toward hot furnace brickwork can cause false flame-on signals due to infrared reflection bleed-over, though UV filters mitigate this.
• Purge Air Integrity: Always maintain clean, dry instrument air to the sensor’s purge connection. A blocked or low-pressure purge line allows heavy combustion soot and heavy fuel oil (HFO) particulate mist to coat the quartz window within hours, resulting in progressive signal attenuation and nuisance low-signal trips.
• Wiring Best Practices: Route the sensor cable separately from high-voltage ignition transformer cables (at least 300 mm clearance) to prevent electromagnetic induction noise spikes from corrupting the high-frequency pulsed signal output. Use shielded twisted-pair cabling with the shield grounded strictly at the control panel end only.

Frequently Asked Questions

What is the primary difference between UV-5 and IR flame sensors in Saacke burner setups?

The UV-5 sensor detects short-wave ultraviolet radiation emitted directly by the chemical reaction of active combustion, making it exceptionally fast at detecting actual flame presence. IR sensors detect infrared flicker, which can sometimes be tricked by glowing refractory bricks. The UV-5 is preferred for clean, dynamic response on oil and gas flames.

Can this FLS09 R.2 unit replace older revisions of the FLS series?

Yes, the R.2 iteration is backward compatible with earlier FLS09 footprints and terminal configurations, provided the associated burner management flame amplifier card supports UV-5 operating parameters.

How do I clean the optical lens if soot accumulation occurs during heavy HFO operation?

Isolate the burner power supply, remove the sensor from the sight tube housing, and gently wipe the quartz glass window using lens cleaning tissue soaked in pure isopropyl alcohol. Never use abrasive cloths or harsh chemical solvents that could scratch or degrade the optical coating.

What causes a “Flame Fault” trip even when the burner is firing normally?

Common root causes include optical lens contamination (soot/oil film), misalignment of the sight tube, degradation of the internal UV phototube due to operational aging, or excessive ambient temperatures exceeding 70°C at the sensor housing body. Verify purge air pressure and check signal voltage using an oscilloscope or multimeter diagnostic menu.