Density monitoring apparatus

A density monitoring gauge is disclosed which modifies a Bourdon tube manometer by introducing a compensating element between the end of the Bourdon tube and the pointer actuating mechanism. The compensating element is designed to accommodate for changes in circumferential length of the Bourdon tube induced by temperature as well as to compensate for pressure changes in a closed system attributed directly to changes in gas temperature within that closed system. The compensating means may consist of a bimetallic member having an OMEGA configuration. Alternatively, the compensating means may include a pair of synthetic material rods connected by a thermally stable member such that linear thermal expansion of the rods is additively connected between the tube spring and the pointer actuating mechanism. The density measuring device is desirably used in connection with sulfur hexafluoride insulated electrical switching gear. If desired, the density monitor may be arranged with an electrical alarm to indicate the presence of a leak.