REPLACING IONIZATION-BASED FLAME RECTIFICATION WITH INFRARED FLAME SUPERVISION IN GAS-FIRED CONVEYOR OVENS: AN ENGINEERING CASE STUDY

Abstract

Direct Spark Ignition (DSI) systems using flame-rectification (ionization) sensing are widely deployed in commercial gas-fired cooking equipment due to their low cost and mechanical simplicity. However, flame-rectification sensing is intrinsically dependent on the physical position of a sensing electrode within the flame envelope, which makes it vulnerable to nuisance shutdowns when gas supply pressure fluctuates, as is common in commercial natural-gas installations during peak-demand periods. This paper presents an engineering case study of a burner safety-system redesign implemented across a fleet of commercial gas-fired conveyor ovens, in which ionization-based flame rectification was replaced with infrared (IR) optical flame supervision. The redesigned architecture decouples flame confirmation from precise electrode placement, instead requiring only that the flame remain within the field of view of a fixed-position IR sensor. Field deployment across eleven converted units at six customer sites is reported, along with operational data indicating a marked reduction in nuisance lockouts, a reduction in equipment returns, and the elimination of recurring on-site technician dispatches previously required for gas-pressure re-regulation. The case study is intended to document a replicable engineering approach for improving burner safety-system robustness in commercial gas appliances subject to variable supply-pressure conditions.