Quantitative determination of air present in refrigerant sample by measurement of pressure coefficient of resonance frequency
US5524477A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 2, 1994 |
| Grant date | Jun 11, 1996 |
| Priority date | — |
| Expiry date | Feb 2, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2291/102
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An acoustic technique is employed to identify the species of a refrigerant gas and whether it contains significant contaminants. Air in the refrigerant can be tolerated, but must be accounted for in determining the acoustic properties of the sample. The refrigerant is admitted into a Helmholtz resonator under a controlled pressure, and a drive frequency is applied to a transducer. Another transducer picks up the vibrations in the resonator and an output signal is compared to the drive signal to find resonant peaks and sharpness factors. The change in resonant frequency with pressure is measured, and is employed to quantify the presence of air in the sample. The amount of air present determines a frequency correction, which permits unambiguous identification of the species of refrigerant and of its purity.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.