The Honeywell Kromschröder PFU series are automatic burner control units that handle the complete sequence of igniting, monitoring, and safeguarding industrial gas burners. In a typical cycle, the PFU checks for flame simulation, performs a pre-purge, initiates ignition, monitors the flame during the safety time, and either releases the burner to continuous operation or locks out with a fault signal — all within a deterministic hardware-sequenced timeline. The units are certified to SIL 3 / PL e per EN 13849, FM Approved, and AGA certified.

Which burner configurations does the PFU series support?

Two architectural variants cover most industrial burner arrangements. The PFU 760 and PFU 778 control directly ignited burners — where the main flame ignites without a separate pilot — for burners of unlimited capacity. The PFU 780 and PFU 798 handle pilot-and-main configurations, where a pilot burner ignites first, is independently monitored, and then lights the main burner. Both burners are supervised separately by a single PFU unit, with independent flame sensors and safety timers for each. All models support intermittent or continuous operation in accordance with EN 746-2.

How does flame detection work across different burner types?

The PFU supports three flame detection methods configured per application. Ionization sensing uses a flame rod inserted in the flame — the flame's conductivity rectifies an AC voltage, producing a DC current signal that the PFU monitors; the switch-off threshold is 1 µA. UV detection uses a UVS 10 or UVD 1 sensor viewing the flame through a quartz window, responding to the 190–270 nm ultraviolet emission. For high-temperature furnaces where the refractory radiates above 750 °C, flame monitoring can be achieved via an external safety temperature monitor with a twin thermocouple — the PFU manages the burner sequencing and safety interlocks while flame detection is handled externally.