Model B5 Sleeve Valve Sizing:
Once the Bailey valve configuration (Inline, YPattern, submerged, angle or nonmodulating) has been selected, the next step in choosing the best solution for the application is sizing the valve for the operating conditions. This is first done by collecting key data, which will be used to determine the severity of cavitation as indicated by the cavitation index sigma (σ) velocity flow and flow capacities(Cv).
Step 1
Maximum Flow Rate > Qmax
Inlet Pressure at Qmax > Pi @ Qmax
Outlet Pressure at Qmax > Po @ Qmax
Minimum Flow Rate > Qmin
Inlet Pressure at Qmin > Pi @ Qmin
Outlet Pressure at Qmin > Po @ Qmin
Step 2  Sigma
The sigma value or cavitation index is calculated and used to configure the performance class of sleeve valve or to determine if alternate options such as ball valves or butterfly valves are acceptable for the application conditions. The following equation is used to calculate the sigma value:
σ = Po  Pv / Pi  Po
Where:
Pi = Inlet Pressure (psig)
Po = Outlet Pressure (psig)
Pv = Vapor Pressure (14.6 psig for 60°F water at sea level)

Step 3  Velocity Flow
The maximum flow rate (Qmax) is compared to the figure in the following sample table to determine the corresponding valve size based on an allowable continuous velocity through the valve port. Higher velocities can be attained for intermittent operating conditions and it is recommended that you contact the factory for sizing. Your flow rate should be rounded up to the nearest table value and record the corresponding valve size. Various units are provided for simplicity.
Step 4  Flow Capacities (Cv)
The maximum flow rate (Qmax) and associated inlet pressure (Pi) and outlet pressure (Po) are used to calculate the required
Flow Capacity of Cv of the application. The Cv equation is as follows: Cv = Q / (Pi  Po) Once the application Cv is calculated from the above equation a safety factor of 20% is added to the value for valve Cv
deviation and potentional nozzle fouling from entrapped debris within the flow media. The Cv plus 20% value (C20) is
compared to the following table to determine the appropriate value size for the application. The chosen valve size must
have a higher capacity than the C20 calculated form the operationg conditions. The valve size chosen from the Cv table is
then compared to the value size chosen from the previous table (Velocity Flow) and the larger of the two valves is the
correct size for the application coditions.
