1. Kv 值, 歐洲水測量法(5~30°C) 100% 開度,升/分鐘 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, 美國水測量法(60oF=15.5℃),加侖/分鐘 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, 氣流,升/分鐘,ΔP=1bar 標準額定流量 Q,即在標準條件下的額定流量,其單位是 l/min。通常對方向控制閥來說,測試時調定的輸入壓力 P1=0.6MPa (6 bar),輸出壓力 P2=0.5MPa (5 bar),即壓降 P=0.1MPa (1 bar) 時,通過被測元件的流量 (ANR,遵循 ISO 8778 ) 即為標準額定流量。