Q=984*Cv
Q(l/min)：标准额定流量
公式成立条件：输入压力P1=0.6MPa (6 bar)，输出压力 P2=0.5MPa (5 bar)，

Cv=1.167Kv
Kv流量单位：m3 / h，气压单位：bar

Kv = 14.3 * Cv
Kv流量单位：l / min，气压单位：bar

1. Kv 值，
欧洲水测量法（5~30°C） 100% 开度，升/分钟
ΔP=1bar Kv (following standard NF E 29312) : The French KV value is an experimental coefficient based on laboratory conditions and expresses the volumetric flow across a valve. The KV coefficient is defined as the flow of water through a fully open valve in litres per minute with a pressure differential ΔP of 1 bar； 
2. Cv 值，
美国水测量法（60ºF=15.5℃），加仑/分钟
ΔP=1psi  Cv : The imperial equivalent of the KV coefficient is the Cv coefficient defined as the flow of water through a valve in US gallon per minute at a differential pressure ΔP of 1 psi across the valve；
3. Q 值，
气流，升/分钟，ΔP=1bar 标准额定流量 Q，即在标准条件下的额定流量，其单位是 l/min。通常对方向控制阀来说，测试时调定的输入压力 P1=0.6MPa (6 bar)，输出压力 P2=0.5MPa (5 bar)，即压降 P=0.1MPa (1 bar) 时，通过被测元件的流量 (ANR，遵循 ISO 8778 ) 即为标准额定流量。