The Model FM is an optical sensor-based device designed to prevent smoke from developing. It senses emissions’ contents, and when signals indicate oxygen is becoming relatively scarce, a control scheme adds oxygen to the flame before the signal reaches a setpoint at which soot would form.

WILLIAMSON CORP.’s new Model FM flare monitor for smokeless flares is designed to prevent smoke before it is produced, rather than reacting to smoke, as most comparable sensors do. The developer said it is the only optical product of its type that is unaffected by the introduction of steam.

The Model FM flare monitor senses the conditions precursory to soot formation, not soot particulates. It monitors the ratio of carbon to oxygen within the flame, and its continuous output signal is proportional to that ratio and, therefore, proportional to the tendency of the flame to smoke. When the signal indicates that oxygen is becoming relatively scarce, a successful control scheme adds oxygen to the flame before the signal reaches the critical setpoint at which soot would form.

Thanks to its narrow-band infrared filters, the Model FM’s output is reliable even through dirty optics, fog, rain, and snow, within limits. Typically, the output signal goes to a proportional-integral-derivative (PID) control system that activates a control valve to modulate the amount of added air or steam as needed, ensuring that there is always ample oxygen for the combustion to be complete, all without the need for operator intervention. For operations that use steam, another benefit of such precision is that no steam is wasted.

The Model FM comes standard with through-the-lens sighting and an adjustable swivel bracket that facilitates installation and alignment. The sensor’s dual-wavelength technology ensures a large target area, further facilitating alignment. The unit, available with a standard (NEMA4/IP65) or rugged (NEMA7/ATEX/IECEx IIB+H2) housing, can be mounted at ground level, typically within approximately 1,500 feet (457 meters) from the base of the stack. The strength of the measured signal decreases with the square of the distance. Optical resolution is D/17 (60 feet at 1,000 feet).

The Model FM flare monitor is a complement to Williamson’s Model PM pilot monitor, which is used to confirm the presence of a stack’s pilot flame.

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