Determination of explosive hazard of gases generated during pyrolysis of motor stator encapsulants

Some motors used in severe shipboard environments (moisture) are protected by encapsulating the stators. When failure occurs, the usual method of removing the windings from the stator is by burning out the insulation in an oven prior to repair and rewinding. This paper deals with the problem of thermal decomposition of encapsulants sufficiently to permit easy removal of the damaged windings without causing run-away fires and explosions during the burn-out operation. This study was made to establish burn-out procedures with more clearly defined safety against fire or explosion. Present Navy instructions require that these ovens operate at a temperature of 350°C and have an exhaust system designed to provide two air changes per minute.