Indicating arrangement for gas filled switchgear ducting - employing float filled with light gas attached to end of pivoted lever arm

The insulating gas pref. sulphur hexafluoride, is used for filling the switchgear enclosure has a specific gravity greater than that of air. The indicator therefore employs a float (4) filled with air, or similar density medium, attached to the end of a pivoted arm (1, 2). A counterweight (3) adjusts the balance. Normally the float rises to a high position (5). If air leaks into the enclosure the float gradually descends until it is visible through a window ( 8) in the enclosure (7). It thus gives a visual signal warning of gas degradation. The float may be a table-tennis ball.