1. How has PSIM been verified?

PSIM is based on the commercial modeling tool AFT Fathom. See AFT Fathom for verification documentation and cases.

2. Does PSIM account for heat transfer in pipe systems?

No. PSIM is an educational tool, and thus neglects heat transfer. PSIM is based on AFT Fathom, which models heat transfer and solves the energy balance along with the flow balance.

3. Does PSIM model transient system behavior?

No. However, but AFT Fathom does.

4. Can I model a non-Newtonian fluid in PSIM?

No. However, but AFT Fathom does.

5. Can PSIM model fire sprinkler systems?

Yes. The Spray Discharge junction is perfectly appropriate for fire sprinklers. The fire sprinkler K values can be entered in directly into the Spray Discharge. In addition, Spray Discharge junctions can be turned on or off with a single mouse click.

6. Can PSIM model ducting system like those in HVAC, ventilation and dust collection systems?

No. However, but AFT Fathom does.

7. Can I keep all of my design cases together in a single file?

No. However, but AFT Fathom does through a feature called Scenario Manager.

8. What is the difference between using a junction to input pressure loss data and the fittings & losses in pipes?

A junction has several advantages. First, solutions are given at all junctions, so the user can check the results at the junction. In contrast, Fittings & Losses are lumped into the pipe and it is not possible to give results at the loss. Second, many junctions (such as valves) have the ability to specify a Restricted Flow Area for cavitation calculations. No such ability exists for Fittings & Losses; thus, cavitation is always ignored for Fittings & Losses. Third, when using a junction the location in the pipe system of the pressure loss is specified. In other words, the upstream and downstream pipe lengths are specified. In the case of Fittings & Losses, it assumed to act like a friction factor and be evenly distributed along the pipe.

The Fittings & Losses approach has the advantage of being able to specify multiple losses quickly and easily, and not cluttering up the model Workspace with numerous junctions.

9. What is the difference between a Reservoir junction and an Assigned Pressure junction?

There is an overlap in capability between the Reservoir junction and an Assigned Pressure junction and frequently they are interchangeable. Here are the differences. The Reservoir junction input pressure always corresponds to stagnation properties. In the Assigned Pressure junction, they can correspond to either static or stagnation properties. If static, only one pipe can be connected. If the stagnation option is used in the Assigned Pressure junction, it will behave identically to a Reservoir junction. Finally, the Reservoir junction allows pipes to connect at different elevations (i.e., depths), and also allows pipes to discharge above the liquid surface level.

10. How does PSIM account for pressure losses at tees and wyes?

PSIM ignores pressure losses at tees and wyes. However, AFT Fathom uses sophisticated models to calculate losses at tees and wyes. The methods, which come from Idelchik, take into account losses that depend on the flow split, area change and angle of the branch pipe.

11. How do I size a pump when there are not any flow control valves?

See Size a Pump

12. How do I size a pump when there are flow control valves?

See Size a Pump with a Flow Control Valve.

13. How do I model a variable speed pump?

Enter the pump data as a polynomial in the Pump Specifications window and then set the pump speed directly. No entry is assumed to be 100% speed. If you enter something other than 100%, PSIM uses the affinity laws to adjust the curve.

14. How do I find the pump speed to obtain a desired flow or pressure?

Enter the pump data as a polynomial in the Pump Specifications window and set the desired flow or pressure on the "Auxiliary Input" folder tab. PSIM will calculate the pump speed required to produce the flow or pressure conditions specified and display the speed in the Pump Summary report.

15. How do I close a valve, pump or pipe?

Select the pipe or junction you want to close and choose Special Condition from the Edit menu. By default, PSIM will display a red "X" next to the pipe or junction label on the Workspace. It will also redraw your Workspace and show the closed sections of the model with dashed lines for the pipes and dashed outlines for each junction.

16. How do I model the pressure drop across a component when there is only one data point?

See Using Manufacturer Pressure Drop Data.

17. How do I show the pipe or junction names on the Workspace?

Open the pipe or junction Specifications window, click the Optional folder tab, and check or clear the check boxes for showing the number or name. This will affect the current pipe or junction. You can set the default behavior in the Workspace Preferences window available on the Options menu.

18. How do I set my preferred engineering units as defaults?

From the Options menu, open the Unit Preferences window. Change to the Unit Preferences folder tab. Choose the Unit Type on the left and the preferred unit you would like to use in the list on the right. Then click the "Set as Preferred Unit" button. At this point, the preferred unit applies only to the current model. To make this the default for all m odels, click the Set as Default button at the bottom.

19. How do I change the input data for multiple pipes or junctions all at one time?

You cannot do this in PSIM. However, you can with AFT Fathom using global editing features.

20. How do I create a liquid mixture?

You cannot do this in PSIM. However, you can with AFT Fathom.

21. How do I merge two models together?

You cannot do this in PSIM. However, you can with AFT Fathom.

22. How do I enable or disable the Highlight feature in the Pipe and Junction Specifications windows?

There are three ways to enable or disable the Highlight feature. The first is toggling the option on the Options menu. The second is pressing the F2 function key while in a Pipe and Junction Specifications window. The third is double-clicking the anywhere in the Pipe and Junction Specifications window.

23. How do I change the reference positive flow direction for one or more pipes?

Select the pipe or pipes and choose the Reverse Direction feature on the Arrange menu.

24. How do I access pipe and junction Specifications windows from the Model Data window?

In the Model Data tabular displays, click the far-left column where the pipe or junction number is located and the appropriate Specifications window will be opened.

25. How do I quickly change the units for an output parameter?

Whereas the Output Control window allows you specify units for all parameters, when in the Output window viewing results you can quickly change the units for parameters in the tabular displays by double-clicking the column header.

26. How do I model elevation changes in my pipe system?

Set the elevations in the elevation fields for each junction. Pipes are assumed to be straight between junctions. If you need to model a system other than a stationary earth-based system, the gravitational acceleration can be changed in the System Properties window.

27. How do I show data for only selected pipes or junctions in Visual Report?

Open the Visual Report Control window, change to the Show Selected Pipes/Jcts folder tab, and use the provided features to specify which pipes and junctions should display data and which should not.

28. How do I make the Pipe Drawing Tool stay active so that I can continue to draw pipes without having to click it each time?

If you hold down the CTRL key when completing the pipe drawing (just before releasing the mouse button), the Pipe Drawing tool remains active, and you can draw a series of pipes without returning to the Toolbox each time. If you double-click the Pipe Drawing tool it remains active until you click it again a single time. This allows you to draw a series of pipes without returning to the Toolbox each time.

29. How do I add graphical segments to a pipe so it is not constrained to a single straight line?

Use the Segment Pipe tool found on the Arrange Menu.

30. How do I change the icon for a junction in PSIM?

Open the Junction Specifications window, click the Optional folder tab, and then click the Change Icon button.

31. Can I customize the junction icons in PSIM?

No, PSIM icons are in a resource file that cannot be edited by the user. This capability is planned for a future release.

32. What is the limit to the size of model I can create with PSIM?

PSIM is an educational tool, and is thus limited to systems with a maximum of 12 pipes and 24 junctions. AFT Fathom allows models up to 10,000 pipes in size.

33. Can AFT Fathom model reacting flows?

No, PSIM models only non-reacting flows.

34. Can I install PSIM onto a local or wide area network?

No. PSIM is an education tool designed to run on local PC’s. However, AFT Fathom can run on networks.