No. 991 is an electrically heated, 350 °F (~177 °C) bench oven currently used for heating parts, including those with emissions of flammable solvents.

Grieve: No. 991 is an electrically heated, 350 °F (~177 °C) bench oven currently used for heating parts, including those with emissions of flammable solvents. Workspace dimensions are 28” wide x 24” deep x 18” high. It has a powered forced exhauster with powered forced airflow safety switch to shut down heat if there is an exhauster failure, as well as a purge timer to allow the oven to exhaust four volumes of fresh air prior to turning on the heat source.