AFT Fathom can EASILY size valves AND orifice plates with a SINGLE Control Valve junction!  There is no need to perform strenuous hand calculations to determine a valve Cv or an orifice diameter.  Just specify the system boundary conditions, pipe input properties, and the desired flow rate (or pressure) and AFT Fathom will calculate the Cv, K factor, and equivalent orifice diameter/area for you all at once!

Figure 1 illustrates a control valve junction at the location of a valve or an orifice plate.  For known flow, use a Flow Control Valve (FCV).  For known upstream pressure, use a Pressure Sustaining Valve (PSV).  Or use a Pressure Reducing Valve (PRV) for a known downstream pressure.

Figure 1: Calculate Cv, K factor, and equivalent orifice size based on known flow of 500 GPM.

Figure 1: Calculations


After specifying the input and running the model, the Cv, K factor, and equivalent orifice size (based upon a discharge coefficient of 0.6) will be displayed in the Valve Summary tab of the Output window.  The results based on a known flow rate of 500 GPM are shown in Figure 2.

Figure 2: Resulting Cv, K factor, and equivalent orifice size using Flow Control Valve.

Figure 2: Results


Finally, to verify AFT Fathom’s ability to size a valve or an orifice plate with a Control Valve junction, build identical systems on the same Workspace using the Duplicate Special feature (click here to read the Duplicate Special feature Tips and Tricks blog post).  Then, morph the duplicated Control Valves into a valve and orifice plate by holding the Control key down and dragging a valve and an orifice junction directly on top of the existing Control Valve junctions.  Figure 3 shows the result of the original Control Valve system that was duplicated twice with Duplicate Special, and then the duplicated Control Valves were morphed to a regular valve and orifice junction.

Figure 3: Select the top system with FCV J2 & Duplicate Special twice. Then morph the FCV in the middle system to a valve and the bottom system to an orifice.

Figure 3: Morphing


Once the resulting Cv or K factor is specified for the valve, and the equivalent orifice diameter with a discharge coefficient of 0.6 is specified for the orifice, the final results in Figure 4 show that the valve and orifice plate were sized correctly.  Notice how the resulting flow rates, valve Cv’s, K factors, and orifice sizes are the same!

Figure 4: Valve J12 and Orifice J22 have been sized correctly based on a Flow Control Valve requirement of 500 GPM.

Figure 4: Resizing