characteristics of the valve. Figure 1 shows the closure characteristics of some standard types of valves. The effective flow area ratio Ao/AF is based on the geometry of the valve and is essentially equivalent to the Cv ratio for the valve. This figure shows, for example, that when a gate valve stem movement position is at 50% open the Cv ratio is 61% while for a ball valve it is only 38%. This means that the ball valve exerts significantly more control on the flow when the valves are in the 50% stem movement position. Valves which exert more control earlier tend to throttle the flow more evenly and, thus, limit the
characteristics of the valve. Figure 1 shows the closure characteristics of some standard types of valves. The effective flow area ratio Ao/AF is based on the geometry of the valve and is essentially equivalent to the Cv ratio for the valve. This figure shows, for example, that when a gate valve stem movement position is at 50% open the Cv ratio is 61% while for a ball valve it is only 38%. This means that the ball valve exerts significantly more control on the flow when the valves are in the 50% stem movement position. Valves which exert more control earlier tend to throttle the flow more evenly and, thus, limit the
Using-Control-Valves-for-Surge-Protection.docx