A Warning message in AFT xStream

Full Message text is:

Relief Valve cycles, unique solution is not possible.

 

This warning is generated by the AFT Arrow Steady Solution, and means the relief valve will not operate in its open or closed state during steady state. When the relief valve is closed in steady state, the pressure exceeds its set pressure, so it opens. When the relief valve is open in steady state, the pressure falls below its blowdown pressure, so it closes.