| 摘要 |
A liquid level gauge (10) of the Blackburn type, for determining the level of water and/or steam in a boiler, utilises multiple optical fibres (44) to intercept light from sources (36) that passes in a relatively straight path through a cross passage (16) in a body (12) of the gauge (10). Due to the difference in the indices of refraction for steam and water, the optical fibres (44) intercept the light when steam is present in the gauge (10), but do not intercept the light when water is present. |
