초록 ▼

A pressure transmitter has a pressure sensor coupled to an isolator diaphragm by a fill fluid such as oil. According to the invention, means are provided for measuring the position of the isolator diaphragm and comparing the measured position with an expected position to give an indication of fill f

A pressure transmitter has a pressure sensor coupled to an isolator diaphragm by a fill fluid such as oil. According to the invention, means are provided for measuring the position of the isolator diaphragm and comparing the measured position with an expected position to give an indication of fill fluid leakage. Non-contact arrangements such as capacitive and ultrasonic techniques are disclosed for measuring isolator diaphragm position, as well as contacting arrangements such as switches. The fill fluid loss arrangement can be incorporated into a two-wire transmitter, which transmitter can be made to send a warning signal to a control unit when fill fluid loss is detected.

대표청구항 ▼

[ What is claimed is:] [2.] In a transmitter having a pressure sensor coupled to an isolator diaphragm by a fluid, a method of detecting fluid loss comprising:monitoring a position of the isolator diaphragm;measuring a temperature that is representative of the isolator diaphragm temperature;ascertai

[ What is claimed is:] [2.] In a transmitter having a pressure sensor coupled to an isolator diaphragm by a fluid, a method of detecting fluid loss comprising:monitoring a position of the isolator diaphragm;measuring a temperature that is representative of the isolator diaphragm temperature;ascertaining an expected position of the isolator diaphragm due to thermal volumetric change of the fluid as a function of the measured temperature; andcomparing the monitored isolator diaphragm position with the expected position.