# Auto-Sizing Pressure Control Valves

From v3.31 onwards, FluidFlow includes a powerful Auto-Size feature which allows engineers to automatically size a range of elements including pressure control valves. This series of examples demonstrates how pressure control valves can be automatically sized. To begin, a standard 1.5 inch butterfly pressure control valve with a Design Pressure set point of 1.18 atm has been modeled in a 10.0 M long 2 inch Schedule 40 steel pipeline. This allows us to establish the flow rate, pressure loss and Cv for this size of element in this system. We can then benchmark our automatically sized element against this base model. Figure 1 shows the data entry for the 1.5 inch valve and Figure 2 gives an overview of the performance of this device in this system. Figure 1: Data entry for 1.5" Pressure Control Valve (Auto Size function set to Off). Figure 2: 1.5" Pressure Control Valve Model (Auto Size function set to Off). We can see in Figure 2 that the calculated Cv is 67.9 usgpm/psi, the friction loss is 14105 Pa and the mass flow rate has been calculated as 6.13 kg/s. Auto-Sizing Pressure Control Valves. Set the Automatically Size field for the controller to "On" and enter a Design Pressure of 1.18 atm. Note, the field titled Valve Model has now been removed from the Input Editor. The Input Editor for the control valve should now appear as shown in Figure 3. Figure 3: Data entry for Auto-Sizing a Pressure Control Valve. Figure 4 shows the calculated results for the controller. As we can see, FluidFlow has established a Cv of 67.9 usgpm/psi, a friction loss of 14105 Pa and a mass flow rate of 6.13 kg/s, 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 (1.5" butterfly valve) or request a proposal from a vendor. Figure 4: Auto-Sizing a Pressure Control Valve. For further information, a detailed example of automatically sizing components is available at: Design Examples | Auto Equipment Sizing.