Pipe X steady state Reynold’s Number is less than 100. Minor Losses may be significantly lower than expected.

A Caution message in AFT Fathom

When Reynolds Numbers fall to extremely low values (i.e. less than 100) the fluid enters a flow regime in which the system losses behave in an unintuitive fashion. Based on relationships depicted by the moody diagram, as the Reynolds Number decreases when below 2000, the friction factor and resulting pressure loss increases. In practice, this relationship breaks down and system losses will begin to decrease somewhere between a Reynolds Number of 10 and 100. Due to limited academic knowledge on this subject, and since the Solver is not currently able to model this regime, a caution message is given.