[en] A test program has been undertaken to identify trendable acoustic parameters and spectra characteristics, obtained during operating flow conditions, which are capable of indicating check valve degradation. Efforts were made to quantify changes in degradation sensitive acoustic parameters and spectral characteristics for various common types of check valves with artificially induced degradations. Acoustic data were acquired during steady-state operating flow with a single accelerometer and a portable, microprocessor-based, vibration data collector. Acoustic parameters and frequency spectra were calculated by the data collector and transferred to a computer database for analysis and trending. This methodology can be implemented in order to augment conventional, commercially available check valve diagnostic systems that can be difficult to apply on a regular basis, and typically require cycling a valve's state in order to analyze degradation