When dealing with compressible fluid, it is often desirable to use standard flow rate units (based on the fluid properties of the gas at 60 F, and 14.7 psia.  This knowledge base article describes how to add SCFM to units in PIPE-FLO.

It is often necessary to perform compressible fluid calculations using flow rate in standard conditions.  Instead of using the volumetric flow rate at an elevated temperature or pressure of the actual flowing conditions, the flow rate is referenced to standard conditions of 60 F and 14.7psia.  

PIPE-FLO allows you to specify your own set of units.  This article describes how to create a conversion factor to support SCFM.  The conversion from SCFM is based on the specific gravity of the fluid in reference to air.  As a result you must enter unique SCFM conversion factor for the specific gas you will be using.  For example for air the SG is 1, for oxygen is 1.105, which has an effect on the conversion value.

To add SCFM to units in PIPE-FLO.

1. Select the System / Settings menu item.
2. Click the Units tab.
3. In the Units drop-down box, select OTHER.
4. In the Name text box, enter SCFM.
5. Select the kg/hr option.
6. In the multiply by text box, enter the conversion factor of 2.0789 times the specific gravity of the gas.
   

The conversion factor from SCFM to kg/hr entered in step 6 is derived as follows:

W(kg/hr) = (r air)*qm*SG*(1/2.205)*(60)

Where,
     W = mass flow rate in kg/hr
     r air = density of air at standard conditions (14.7 psia, 60°F)
     qm = flow rate in SCFM
     SG = specific gravity of the gas compared to air
     (1/2.205) = conversion from lb to kg
     (60) = conversion from minutes to hr

For example, if your gas is air (SG = 1), the conversion factor would be 2.0789.