For some fluids ECS fails at low temperature because reference fluid is out of range

[ibell]

See for instance

Traceback (most recent call last):
  File "c:\python27\lib\site-packages\matplotlib\sphinxext\plot_directive.py", line 515, in run_code
    exec code in ns
  File "<string>", line 22, in <module>
  File "CoolProp.pyx", line 250, in CoolProp.CoolProp.Props (build\temp.win32-2.7\Release\pyrex\CoolProp\CoolProp.cpp:21200)
  File "CoolProp.pyx", line 364, in CoolProp.CoolProp.Props (build\temp.win32-2.7\Release\pyrex\CoolProp\CoolProp.cpp:19467)
ValueError: CoolProp error: Your temperature to saturation_T [255.03 K] is below the minimum temp [263.6 K] :: inputs were:"V",'T',2.4755099999999999e+02,'Q',0.0000000000000000e+00,"n-Undecane"