The kinetic term in a kinetic air valve simply refers to the valve's ability to vent air under kinetic flow conditions i.e. during filling of the pipeline or during dynamic flow conditions. Since many air release valves have a tendency to close during pipeline filling due to a buildup of air pressure while venting, a "kinetic" valve has sufficient weight and mass in it's valve chamber to stay open during these conditions allowing full venting of air during pipeline filling, a very critical period. A kinetic valve will also usually operate as a vacuum relief, should that be necessary. The other type of valve is an air release, which is only designed to vent air under pressure, after the pipeline is filled and in service. A double purpose valve simply has te ability to do both jobs: vent air while filling of pipeline, and vent air accumulated during normal operation and under pressure, epbpe.
for a very detailed engineering explanation. Many valves are labelled "kinetic" but in fact dont meet the intention of the invention. From memory kinetic air valves were invented by Glenfield and Kennedy in Scotland. The design has been copied and varied by many others. Until Ventomat entered the scene it was surrounded in myth and legend. Sharing knowledge is a way to immortality