Instead of entering performance curve data, you can also specify a fixed flow rate and have PIPE-FLO Compressible calculate the developed pressure.  When troubleshooting fixed flow compressor installations, it is helpful to know how PIPE-FLO Compressible internally models them.

A schematic of how PIPE-FLO internally models fixed flow compressors is shown below in Figure 1:


Figure 1.  How the program internally models a compressor set to a fixed flow rate

The following points about fixed flow rate compressors should be noted:

• When a fixed flow rate is specified for a compressor, the performance curve data (if specified) is overridden.
  
  
• PIPE-FLO Compressible models a fixed flow compressor by creating two nodes in the system where the compressor is installed (refer to the figure).  A flow demand value equal to the set flow rate is taken out of the first compressor node (the inlet node) and an equal flow demand is set entering the second node (the outlet node).
  
  
• If a compressor status is listed as invalid, it means that you have set the flow rate lower than what would naturally occur through the line if the compressor was not installed.  The compressor then acts as "valve" in order to limit the flow rate to the set value.  If this occurs, you should either increase the set flow rate or remove the compressor.
  

PIPE-FLO Compressible balances the network and calculates the pressure at each node.  The program checks the calculated results to insure that the compressor is operating properly (the inlet pressure must be less than the outlet pressure).