Calculator
How the calculation works
For an incompressible liquid (no flashing or cavitation), the flow coefficient is derived from the basic valve sizing equation:
Kv = Q × √( SG / ΔP ) (Q in m³/h, ΔP in bar)
Cv = 1.156 × Kv (Cv in US gpm, ΔP in psi)
Where Q is the volumetric flow rate, SG is the specific gravity of the fluid relative to water, and ΔP is the pressure drop across the valve at the desired flow. The tool picks the smallest standard DN whose rated Cv (with a 15–25% margin) covers your requirement, so the valve is never run near its choke limit.
Gas, steam and two-phase flows need additional correction factors (Fk, xt, expansion). For those services, contact our engineering team with your operating data.
Typical Cv capacity by size (butterfly, reference)
| DN | Rated Cv (approx.) | Rated Kv (approx.) |
|---|---|---|
| DN50 | 95 | 82 |
| DN65 | 150 | 130 |
| DN80 | 210 | 182 |
| DN100 | 340 | 294 |
| DN125 | 540 | 467 |
| DN150 | 760 | 657 |
| DN200 | 1400 | 1211 |
| DN250 | 2200 | 1903 |
| DN300 | 3100 | 2681 |
| DN400 | 6000 | 5192 |
Values are indicative for centric/wafer butterfly valves and vary with seat and disc design. Use them for first-pass selection only.
Need the actual valve?
Reguvale manufactures wafer & lug butterfly valves, pneumatically actuated butterfly valves and control valves in DN50–DN400, PN10/PN16, with EPDM / PTFE seats. Send us your calculated Cv, medium and temperature and we will confirm the exact model and quote FOB Tianjin.
Full product range: All Products.