Liquid level controller
US4923489A · kind A · utility
Inventor
Key dates
| Filing date | Jun 23, 1989 |
| Grant date | May 8, 1990 |
| Priority date | — |
| Expiry date | Jun 23, 2009 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01F23/14
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A liquid level controller for a waterpan-type spray booth. The controller comprises a normally-open first air pressure sensor and switch for detecting a minimum level of negative static pressure through the restricted opening indicative of ventilation fan operation and for closing the first air pressure sensor and switch to thereby permit a voltage output. A normally-closed second air pressure sensor and switch is provided for sensing a predetermined negative static pressure level indicative of a minimum adequate air flow through the restricted opening for opening the second air pressure sensor and switch to interrupt a current flow through the second sensor and switch. The normally-closed second air pressure sensor is normally closed by the voltage output from the normally-open first air pressure sensor and switch. The first and the second air pressure sensor and switch are operatively connected to a water supply valve. A decrease in negative static pressure resulting from a drop in water level in the water pan and a consequent increase in the size of the restricted opening defined by the water level and washing enclosure returns the normally-closed second air pressure sensor and …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.