If a fluid is not available in an engineering data table, you have two options:

(1) Create your own table using Table Manager.
(2) Create a custom fluid by manually entering the fluid properties.

Option 1: Creating a table with Table Manager
If you have a set of property data for your fluid, you can use that data to generate polynomial equations for the vapor pressure, density, viscosity, and heat capacity.  These equations can then be used to create a table using PIPE-FLO's table building module, Table Manager.

Step 1:  Gather the data
Generally the more data you have, the better.  Also, if you will only be using your fluid over a limited temperature range, you could concentrate your data points in that range.  For example, suppose that you have fluid property charts ranging from 35°F to 300°F, but you only plan to use the table between 100°F and 200°F.  In that case, you could limit the table range and concentrate the data points between 100°F and 200°F.  Note that you may not need all of the properties listed above.  For example, if you are creating a liquid only table, you do not need heat capacity data for your table.

Step 2:  Generate the polynomial equations
To assist in developing the equation coefficients, a regression macro that runs under Excel is provided with PIPE-FLO.  The regression macro calculates the coefficients of an Nth order equation using the method of least squares.

The regression macro (regression.xls) is located in the same folder as the PIPE-FLO program.  You can also click on the file link below to download the macro.

How to use the Regression Macro
The regression macro calculates the coefficients of a polynomial equation from a given set of data.  Before using the macro, you should have your data ready.  A maximum of 1000 data points may be used.

1. Start Excel and open the regression macro.
2. Select the liquid density, liquid viscosity, vapor pressure, vapor viscosity, or heat capacity worksheet.
3. Enter the degree of equation (the maximum degree that can be used is 4).

NOTE:  The cells where you enter data are a light yellow color.

4. Enter the temperature vs. fluid property data.

NOTE:  The data must be in the units indicated in the column headings.  If your data is in different units, you can enter it in columns to the right of the shaded cells and set up formulas in the shaded cells that convert the data to the required units.

5. Click the Calc Coefficients button.  The equation coefficients are calculated.
6. Continue to calculate the equation coefficients for each property as described in steps 2 through 5.

Step 3:  Create the table with Table Manager
Once you have the equation coefficients you are ready to create a table using Table Manager.  To start Table Manager, select the Tools / Data Tables menu item in PIPE-FLO.  Click the Fluid Tables button and start entering the fluid data and equations.  For detailed information about how to create a fluid table in Table Manager, see the program online help.

NOTE: In addition to using a polynomial equation, you also have the option of selecting DIPPR and Yaws equations for the fluid properties.


Option 2:  Entering a custom fluid
Sometimes it is not possible to generate polynomial equations for a fluid data table.  For example, you may have only one or two data points for each fluid property, or a polynomial cannot be generated that adequately fits the data.  In such cases, the best option is to use PIPE-FLO's custom fluid feature.

To enter a custom fluid:
1. Choose the System / Settings menu item.
2. Click the Fluids tab.
3. Click the Add or Edit fluid zones button.
4. Click the New button.
5. Enter the fluid zone name in the Name text box.
6. Specify a fluid name in the Custom fluid text box.
7. Select the fluid state (Liquid or Vapor).
8. Specify the Temperature, Pressure, Density, and Viscosity.  For liquids, the Vapor press and Critical press must be specified.  For vapors, the Sp heat ratio must be specified.
9. Click OK.

TIP: If you use a particular custom fluid often, you may want to create several different fluid zones that cover the temperature/pressure range that you normally operate within.  Once you have created the fluid zones, choose the File / Save Design File menu item to save them in a design file.  The next time you create a system that uses one of your custom fluids, start the project using the custom fluid design file.

To create a new PIPE-FLO system using a design file:
1. Click the New button on the program toolbar.
2. Click the Open button at the bottom of the System Settings & Properties dialog box.
3. Select a design file.
4. Click the Open button.  The fluid zones are loaded into your new project.