Absolute zero pressure cannot be physically obtained in a fluid piping system. This warning indicates that the boundary conditions established in the PIPE-FLO model result in a pressure calculated below absolute zero. This may be caused by flow rates that result in high values of head loss and pressure drop.
If the pressure units are set to gauge pressure, the calculated value will be less than the negative value of the atmospheric pressure. Negative gauge pressure values indicate a vacuum exists.
Version 12 and Above
Starting in version 12, this message is based on the calculated static pressure at the inlet and outlet of the pipe attached to the device.
Version 2009 and Before
Pressure < Absolute Zero – Calculated Result is not Valid (Nodes, Demands, Components, Control Valves, and Pumps):
This warning occurs when PIPE-FLO calculates the total pressure to be less than absolute zero.