Water Control Valves - Flow Factor Kv Diagram
Sizing of water control valves using the flow factor Kv in SI units. Estimate Kv values based on pressure drop and flow rate through water control valves.
Water Control Valves - Flow Factor Kv Diagram
Sizing of water control valves - SI units
Overview
The flow factor Kv for control valves in water systems can be estimated from pressure drop and flow rate.
Key Notes:
- 1 bar = 1×10⁵ Pa (N/m²)
- Larger valves (with larger Kv) reduce maximum pressure modulating spans, limiting control stability
- Control valves are often one to two dimensions below the connecting pipe dimensions
Example
With a water flow of 5 liter/s:
- Pipe size would be in range: 3-4 inches (80-100 mm nominal)
- Control valve size: Kv ~ 20 or 2-3 inches (50-80 mm nominal)