Differential pressure measuring apparatus

US5111698A · kind A · utility

Assignee

• Endress u Hauser GmbH u Co. · DE

Inventors

• Karlheinz Banholzer · Eschborn, DE
• Peter Gerst · Weil am Rhein, DE
• Peter Jung · Balingen, DE

Key dates

• Filing date: Jul 29, 1991
• Grant date: May 12, 1992
• Expiry date: Jul 29, 2011

Classification

• Technology area (CPC G): Physics
• CPC primary: G01L9/125
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

The differential pressure measuring apparatus comprises a single chamber differential pressure sensor having two resilient sensor diaphragms which enclose a volume filled with a fluid. In the single chamber differential pressure sensor two measuring capacitors are formed whose capacitances vary in opposite senses in response to the sensor differential pressure between the pressures acting on the two sensor diaphragms. The single chamber differential pressure sensor is connected to an adaptor comprising a volume filled with a fluid which is closed on the one hand by one of the two sensor diaphragms and on the other hand by an elastic adaptor diaphragm. An evaluation circuit calculates the sensor differential pressure from the capacitances of the measuring capacitors. The evaluation circuit comprises a first compensation arrangment which compensates the influences of the sensor temperature and of the sensor parameters on the calculated sensor differential pressure, and a second compensation arrangement which compensates the influences of the adaptor temperature and of the adaptor parameters on the sensor differential pressure corrected by the first compensation arrangement.