Patent ID: 6978779

Claim:
A method for use with a discharging means discharging a fluid substance into a receiving gas, said method determining the pressure of the receiving gas, said method comprising the steps of: (a) placing the discharging means in fluid communication with the receiving gas so that a bidirectional mechanical-electrical conversion element is subjected to mechanical loading responsive to the gas pressure of the receiving gas, the element mechanically vibrating responsive to the application of alternating electrical energization to the element, the element having an admittance, the admittance of the element at a given frequency of alternating electrical energization being alterable by a mechanical loading of the element; (b) applying alternating electrical energization to the element at a selected frequency; (c) subjecting the element to mechanical loading responsive to the pressure of the receiving gas; (d) measuring the admittance exhibited by the element in the loaded condition when energized by the electrical energization of the selected frequency; and (e) determining the difference between the admittance measured in step (d) and another value as an indication of the pressure of the receiving gas.