# Auto-Sizing Flow Control Valves

From v3.31 onwards, FluidFlow includes a powerful Auto-Size feature which allows engineers to automatically size a range of elements including flow control valves. This series of examples demonstrates how these valves can be automatically sized. To begin, a standard 2 inch butterfly valve with a design flow rate of 10m3/h has been modeled in a 20.0 ft long 2 inch Schedule 40 steel pipeline transporting water. This allows us to establish the pressure loss and Cv for this size of element in this system. We can then benchmark our automatically sized element against this base model. A copy of this model can be found in the folder: "QA Equipment Sizing". Figure 1 shows the data entry for the 2 inch valve and Figure 2 gives an overview of the performance of this device in this system. Figure 1: Data entry for 2" Flow Control Valve (Auto Size function set to Off). Figure 2: 2" Flow Control Valve Model (Auto Size function set to Off). We can see in Figure 2 that the calculated Cv is 15.9 usgpm/psi and the friction loss is 52990 Pa. Auto-Sizing Flow Control Valves. Set the Automatically Size field for the controller to "On" and enter a design flow rate of 10m3/h. Note, the field titled Valve Model has now been removed from the Input Editor. The Input Editor for the valve should now appear as shown in Figure 3. Figure 3: Data entry for Auto-Sizing a Flow Control Valve. Figure 4 shows the calculated results for the valve. As we can see, FluidFlow has established a Cv of 15.9 usgpm/psi and a friction loss of 52990 Pa, i.e., exactly matching the results from Figure 2. The element has therefore been automatically sized successfully. We can now select a suitable valve model from the database (2" butterfly valve) or request a proposal from a vendor. Figure 4: Auto-Sizing a Flow Control Valve. For further information, a detailed example of automatically sizing components is available at: Design Examples | Auto Equipment Sizing.