Framed Sectional Drawing

Framed Sectional Drawing, full size, of Bailey's Copper Cap Fusible Plug No.46186

This sectional drawing was made in the Museum, and shows a fusible plug designed for use as a safety device with steam boilers. the plug is fitted between the furnace and water space above it - if the water level falls too low, risking a boiler explosion, the fusible metal in the plug melts and steam is vented into the furnace, alerting the operator to the potential for a boiler explosion. Theplug consists of a socket screwed for fixing to the furnace crown and provided above with a nut. It was patented in 1885 by Sir W. H. Bailey. Fusible metal, in the form of a thick disc, covered above with a thin copper cap, is secured to the socket by the nut as shown in the adjacent drawing. The copper cap is intended to protect the fusible alloy from any chemical action of the water and to insure a sudden and complete release of the plug.