Valves and Fitting Losses

You can calculate the pressure drop for a specified flow rate through any of the valves & fittings in the Standard Valve & Fitting table.  This feature is available for all PIPE-FLO users. The Standard valve & fitting table is used to calculate and install resistance coefficients into pipelines for a variety of common valves and fittings.  The Standard table includes the valves and fittings listed in Appendix A of Crane's Technical Paper #410 "Flow of Fluids Through Valves, Fittings, and Pipe".  

The resistance coefficient K is calculated from the following relation:

{K = \bigg( f \times \frac{L}{D}\bigg)}

Where:

  • f = turbulent friction factor (calculated from clean commercial steel pipe)
  • {\frac{L}{D}} = equivalent length of a resistance to flow, in pipe diameters

You can also calculate the dP across any individual valve or fitting directly from the pipeline graph window in PIPE-FLO Professional 2009.

Steps to Calculate Valve Losses

  1. Initiate a project with definitions for system units, pipe materials and fluid zones in the System Settings & Properties dialog box.
    • If you do not have a design file already saved with these parameters, create a new one by creating a new system.  In the System Settings & Properties dialog box, specify the engineering units on the Units tab.  Specify the pipe materials on the Specifications tab.  And specify the fluids on the Fluids tab.
    • After you have specified the above information, click OK to save the project settings and access the FLO-Sheet.
  2. Draw a pipeline on the FLO-Sheet.
    • Select the Drawing tool button .
    • Click once on the FLO Sheet to start the pipeline.
    • Drag the line over and double-click the end to complete the pipeline.

  3. Design the pipeline..
    • Click the Select tool button .
    • Double-click on the pipeline.
    • Choose your pipe Specification and Fluid zone from the drop-down lists.
    • Specify a pipe Length and Size.
    • Specify the connection Elevations as zero ft.
  4. Install the Valve or an equivalent Fixed Resistance.
    • Click the Valves & Fittings tab in the Pipeline dialog box.
    • To install an isolation valve from Crane TP #410, click the Isolation Valve button .  Select and Add one of the valves.
    • To install a check valve from Crane TP #410, click the Check Valve button .  Select and Add one of the valves.
    • To install a fixed resistance, click the Other Resistance button .  Select Fixed K, Fixed Cv or Fixed Kv, specify the appropriate value, and then click the Add button.
  5. Graph the pipeline and calculate the dP across the valve.
    • Click back on the Pipe tab, or double-click on the pipeline if you already closed the dialog box..
    • Click the Graph button .
    • Specify the desired flow rate in the Flow field.
    • Hit Enter on your keyboard to update the data.
    • The pressure drop due to valves & fittings will be listed in the mL (minor losses) field.  See Figure 1.


Figure 1 - Pipeline Graph Window