A number used to describe the ratio between the pressure recovery after the vena contracta and the pressure drop at the vena contracta. It is a measure of the amount of pressure recovered between the vena contracta and the valve outlet.
Some manufacturers use the term Km to describe the pressure recovery factor. This number will be high (0.9) for a globe style valve with a torturous follow path and lower (0.8 to 0.6) for a rotary style valve with a streamlined flow path.