# Valves

FluidFlow contains a database of two-port valves which can be used when building a network. The user can also very easily add new valves to the database for specific modelling applications. Note, you only need to add a component to the database once. It will then be stored for all future projects. This section of the help file outlines the information required when adding a new valve to the database. Figure 1: Data Entry for Two-Port Valves. Name: Allows you to enter a descriptive name for this element. Manufacturer: The name of the valve manufacturer can be entered here. Materials: The materials used to manufacture the valve may be defined in this field. Options include: Brass, Copper, Steel, etc. Applications: This option allows you to list the specific applications in which the valve may be used. Options include: Chemical, Power, etc. Max Operating Pressure: If there is a maximum pressure rating for the valve you should enter this value here. Leaving the value at 0 means that FluidFlow will not make an overpressure check. Pressure Unit: The pressure units used when defining the Max Operating Pressure. Size: This refers to the diameter of the valve opening. Size Unit: This refers to the diameter/size units used in the above entry. Defined By: Two-port valves can be defined in the Database in a number of ways as set out in Figure 2. Figure 2: Pressure Loss Relationship for Two-Port Valves. If you intend "manually" editing the % opening of a valve in your system and modelling the effects of this design change, we need to ensure that the flow vs. pressure loss data for the valve has been defined in the database. Many valves in the database have the flow vs. pressure loss defined. This relationship can be defined by: 1) K with positioning, 2) Kf with positioning or 3) Cv,Kv with positioning. If a valve has been defined in the database by: 1) K no positioning, 2) Kf no positioning and 3) Cv-usgpm/psi no positioning, 4) Kv-m3/h/kPa no positioning or 5) Kv-l/min/bar no positioning, we will not be able to model changes in the % opening of the valve from the Input Inspector. Curve Data: The valve curve coordinates can be defined in this field. Simply enter the coordinates as provided by the manufacturer in the columns on the left hand side. FluidFlow will automatically create the curve-fit once a minimum of three coordinates have been defined. Note, by default, the software displays one row for % Open vs. Cv(Cv usgpm/psi) units in the "Curve Fit" editor. Use the "Down Arrow" key or Select "ADD" if you need to create additional rows for the curve coordinates. Figure 3: Curve-Fit Data Entry for a Two-Port Valve. Note, users can select the most accurate curve-fit and equation order from the top left hand corner of the Curve Fit dialog. It is also important to set the Min & Max Limits as these will form the basis of any warning generated when the valve is solved in a system, i.e if we solve a system such that the operating point for the valve is outside the min and max limits, we will get a warning in the Messages tab to that effect. If any of the above is unclear or you require any further information, please contact us at: support@fluidflowinfo.com.