球形止回阀，截止止回阀，提升式止回阀的流量特性曲线
Characteristic Flow Curves for Globe Stop, Stop-Check, Lift-Check Valves

小于全开状态的估计流量系数Cv
Estimating Cv For Less Than Fully Open Valves

图2
球形止回阀，截止止回阀和提升式止回阀
Figure 2
Globe Stop, Stop-Check and
Lift-Check Valves

　　表中所列流量系数仅适用于全开状态下的阀门。不是全开状态的流量系数可以采用适用于提升式阀瓣止回阀和截止阀的流量特性曲线进行估算。不建议将闸阀用在节流应用中。
　　The flow coefficient (Cv) listed in the tables apply to fully open valves only. Flow coefficients at other than fully open may be approximated by use of the characteristic flow curves for tilting disc check and globe valves. Gate valves are not recommended for throttling service.

例：
　　DN300，压力等级Class 900的美国太平洋压力密封截止阀在开气度为1/4时的流量系数是多少？
EXAMPLE:
　　What is the Cv of a 12 inch Class 900 Pacific pressure seal globe valve 1/4 open?

图3
Y形球形止回阀，截止止回阀和提升式止回阀
Figure 3
Y-Globe Stop, Stop-Check and
Lift-Check Valves

解：
　　从上列流量系数表中得到，DN300，压力等级Class 900截止阀在全开状态下的Cv是1820。
SOLUTION:
　　From the flow coefficient table above, the fully open Cv for a 12 inch, Class 900 globe valve is 1820.

　　查询图2，全开状态的1/4时阀门的比率是52%.
　　Consulting Figure 2, the percent of fully open Cv at 1/4 valve open is 52%.

　　因此计算1/4全开的流量系数Cv为：
　　0.52 x 1820 = 946.
　　The Cv at 1/4 open is then computed as:
　　0.52 x 1820 = 946.