SYSTEM FOR MEASURING PRESSURE AND TEMPERATURE
|Owner||TECHNI AS (Norway)|
AbstractThe present invention relates to system for measuring pressure and temperature based on change in the characteristic properties of a medium for ultrasound under the effect of pressure and temperature. The invention is based on two waveguides where geometry is adapted to the medium's characteristic properties for ultrasound such that only planar pressure waves are generated in the waveguides. The first of the waveguides is arranged for measuring temperature due to thermal expansion of the medium, where the medium is pressure-compensated by means of an internal compensator to prevent thermal pressure accumulation, and where measuring temperature is based on the medium's specific known characteristic data for ultrasound under the effect of temperature under constant pressure. The second waveguide is arranged for measuring pressure, based on waveguide and the medium's known characteristic properties for thermal expansion and pressure, and where the thermal effect is corrected analytically based on measurement of temperature in the first channel. The physical principle of the invention is based on the properties of a medium (oil) where the stability for high temperature and pressure is crucial for long-term properties. Long-term properties of ultrasound sensors are not physically linked to the medium's properties, such that change in characteristic properties of ultrasound sensors does not impair the accuracy of the medium unless the function of the ultrasound sensors ceases. The physical principle of the invention allows an arrangement where ultrasound sensors can be separated from measuring channels by a pressure barrier, such that the integrity of the pressure barrier is not broken.
IPC Classes ?
- G01N 29/024 - Analysing fluids by measuring propagation velocity or propagation time of acoustic waves
- G01N 29/036 - Analysing fluids by measuring frequency or resonance of acoustic waves
- G01N 29/32 - Arrangements for suppressing undesired influences, e.g. temperature or pressure variations
- G01K 11/22 - Measuring temperature based on physical or chemical changes not covered by group , , , or using measurement of acoustic effects