This calculator is used to size gas control valves. The calculator determines the valve flow coefficient (Cv) required for a specified gas flow rate and pressure drop. The calculator can handle non-choked and choked flow. The calculation method is based on the International Electrotechnical Commission procedure described in the Emerson Control Valve Handbook.
The calculator determines the valve flow coefficient (Cv) required for the valve to pass a specified gas flow rate with specified upstream and downstream pressures.
The calculator can handle non-choked and choked flow.
- Enter the mass flow rate of gas the valve must pass
- Enter the pressures upstream and downstream of the valve
- Enter the fluid physical properties
- Enter the valve pressure drop ratio factor
- This can be obtained from valve manufacturer's literature
- Typical values for globe valves range from 0.50 to 0.92
- Enter the piping geometry factor
- If no fittings are connected to the valve this factor is 1
- If fittings such as reducers are fitted to the valve the geometry factor can be calculated using the procedure described in the "Gas Control Valve Sizing Calculator Guide"
- Click the "Calculate" button
- The calculator will determine the valve Cv
- The calculator will also determine if the flow is critical or not through the valve