The Gill Sensors & Controls AF120 is a closed-loop air/fuel ratio controller designed for stationary gas-fueled engines used in combined heat and power (CHP), power generation, gas compression, and pumping installations. It uses a wideband UEGO (Universal Exhaust Gas Oxygen) sensor to continuously measure exhaust oxygen content and adjusts the fuel delivery valve via a PI (Proportional + Integral) control algorithm to maintain the target Lambda setpoint — minimizing emissions while maximizing combustion efficiency.

How does the AF120 control air/fuel ratio across different engine types?

The AF120 supports three control configurations from a single module: carburettor bypass using the Gill AF120 stepper-motor fuel valve, fuel pressure regulator manipulation, and turbo wastegate control via the 4–20 mA output. It operates with both stoichiometric (rich-burn) engines equipped with three-way catalytic converters and lean-burn engines with or without aftertreatment. A programmable load map driven by throttle position or MAP sensor input adjusts the Lambda target dynamically as engine load changes, while the stepper motor drive with over 200 steps provides fine-grained valve positioning near the set point for stable combustion under transient conditions.

What makes it suitable for harsh industrial engine environments?

The controller is sealed to IP67 for direct engine-mount installation and operates across a -40 to +90 °C ambient temperature range. It is CSA certified for Class 1 Division 2 Groups C and D hazardous locations when housed in the EH12 shielded enclosure. RS232 connectivity allows parameter configuration — including valve start position, warm-up time, and load map breakpoints — via the Windows-based GUI without opening the sealed housing. Three front-panel LEDs provide at-a-glance power, standby, and operating status indication.