| 摘要 |
An improved flood level sensor has an upstanding, vented tube extending above and outside a receptacle while maintaining fluid communication with an enclosed rim of the receptacle. A partial vacuum is communicated to an orifice which is located within the tube at a height related to a limit on the level of fluid in the receptacle. The level of fluid in the tube depends upon the fluid pressure in the enclosed rim and therefore upon the fluid level in the receptacle. When the fluid level in the receptacle is below flood level, the orifice is able to relieve any partial vacuum communicated to it. However, when the level of fluid in the receptacle rises to the flood level, the fluid level in the tube rises to partially seal the orifice and prevent relief of the partial vacuum which then actuates a valve lockout device. |
