Monitoring system for mine ventilation fans - has two flow vanes each operating a shutter over photoelectric cell

摘要

A circular vane (1) is pivoted in the fan air flow. It carries a rod (2) on the end of which s a shutter (3) which projects into an optical box (4) containing a lamp and a photoelectric cell. As the vane (1) is deflected by the air flow the shutter obscures the light falling on the cell to a greater or lesser extent. The cell operates an electric relay which illuminates a green lamp for healthy conditions and a red lamp when a dangerous condition is reached. Two such assemblied are mounted behind each other and can be set to react at different points on the fan characteristic. The setting can be varies by adjustment of the optical box (4) on its support (6).