Double Flange Butterfly Valve

Butterfly Valve Flow Coefficient Kv & Pressure Drop Reference Data

All concentric lug butterfly valves and wafer butterfly valves are equipped with complete opening-angle Kv flow coefficient table and GPM-PSI pressure drop nomograph, supporting metric & imperial dual-system pipeline design calculation for global industrial projects. Flow coefficient Kv represents the fluid throughput capacity of the valve; higher Kv value brings lower pipeline pressure loss and less operation energy consumption.

1. Kv Value Table at Different Opening Angle (DN50 ~ DN600, 10°~90° Full Open)

Table Instruction: Small opening 10°~30° for precise flow throttling; medium opening 40°~70° for circulating water regulation; 90° full open delivers maximum Kv value with minimum flow resistance for main pipeline isolation.

2. GPM & PSI Pressure Drop Nomograph Chart

Figure 1: Flow Rate & Pressure Drop Nomograph for Concentric Butterfly Valve

The pressure drop curve chart adopts US imperial units, with horizontal axis for flow rate GPM and vertical axis for differential pressure (PSI / Feet water head). Diagonal slant lines correspond to matching Kv/Cv flow coefficients, helping North American and ANSI standard clients quickly calculate pipeline medium pressure loss.

• Horizontal axis: Flow range 100 ~ 100,000 Gallons Per Minute, covers DN50~DN600 full size flow demand;
• Vertical axis dual units: PSI pressure difference and Feet water head, convenient for direct conversion of pipeline design parameters;
• Operation logic: Locate flow GPM vertically intersect Kv diagonal line, horizontally read pressure drop value to judge system energy loss.

3. Combined Application of Kv Table & Pressure Drop Curve

• Step 1: Confirm working opening angle (throttling / full open), extract Kv value from the table;
• Step 2: Convert metric Kv to US Cv via formula: Cv = Kv × 1.156;
• Step 3: Match Cv diagonal line on the GPM-PSI nomograph, calculate actual pipeline differential pressure;
• Step 4: If pressure drop exceeds design allowable value, upgrade to larger DN butterfly valve to raise overall Kv flow capacity.