The High Pressure Constant Volume Regulator limits airflow to a set maximum volume (CFM). Its effective pressure range is between 0.6 and 2.4 InWC. The CVR “wing” starts to fly and therefore comes online a little earlier. It provides a little bit of resolution at the high end of the spectrum.
High Pressure CVRs are available in 3″, 4″, 5″, 6″, 8″ and 10″ sizes with airflow ranges between 15 and 720 CFM.