Full Port vs Reduced Port Ball Valve: Flow, Pressure Drop & Cost Comparison
Key Takeaway
A full port ball valve has a bore diameter matching the pipe ID, delivering near-zero flow restriction and 30–50% higher Cv than a reduced port design. A reduced port valve uses a bore one or two sizes smaller than the pipe, costing 15–30% less. Choose based on your system's pressure drop tolerance, Cv requirements, and budget.
What Is a Full Port Ball Valve?
A full port (also called "full bore") ball valve has a ball bore diameter equal to the nominal pipe ID. For example, a 1-inch full port valve has a ~25.4mm bore that matches a Schedule 40 pipe. When fully open, the fluid passes through with virtually no pressure drop. Per API 608 and ISO 17292, full port valves must achieve a Cv at least 90% of the theoretical maximum pipe flow.
Best applications: Pipeline pigging, high-viscosity fluids, systems requiring maximum flow (e.g., data center CDU main loops).
What Is a Reduced Port Ball Valve?
A reduced port ball valve has a bore one nominal size smaller than the pipe. For example, a 1-inch reduced port valve has a ~19mm bore (equivalent to a 3/4" pipe). The fluid accelerates through the constriction, creating additional pressure drop.
Best applications: Branch lines, low-flow systems, cost-sensitive bulk orders (e.g., HVAC branch piping).
How Do Cv Values Compare Between Full Port and Reduced Port?
| Valve Size | Full Port Cv | Reduced Port Cv | Cv Difference | Pressure Drop Impact |
|---|---|---|---|---|
| 1/2" | 18 | 8 | -56% | +125% |
| 3/4" | 34 | 17 | -50% | +100% |
| 1" | 60 | 30 | -50% | +100% |
| 1-1/2" | 130 | 70 | -46% | +86% |
| 2" | 220 | 120 | -45% | +83% |
Data based on ASME B16.34 standards and LINS Valve product testing.
Which Should You Choose for Data Center Liquid Cooling?
For AI data center CDU (Coolant Distribution Unit) systems, LINS Valve recommends:
| Location in System | Recommended Port | Reason |
|---|---|---|
| Main Loop | Full Port | Unrestricted glycol-water coolant flow for maximum heat dissipation |
| CDU Isolation Valves | Full Port 3PC | Maintenance access without system shutdown |
| Branch Lines | Reduced Port | Lower flow requirements, cost savings |
| Server Rack Supply/Return | Reduced Port | Adequate flow for individual rack cooling |
| Bypass Lines | Full Port | Must handle full system flow during maintenance |