\documentclass[border=3mm]{standalone}
\usepackage{luacoolprop}
\pgfplotsset{compat=1.18}
\pgfplotsset{auto node allow outside=true,
  auto node failure mode=hide-low-priority}

\begin{document}
\LCPPHDiagram[
  fluid=Propane,
  isotherm=true,
  isentrope=true,
  quality step=0.2,
  temperature values={-40,-20,0,20,40,60,80},
  entropy values={1.4,1.6,1.8,2.0,2.2},
  labels=true,
  sloped labels=true,
  label placement=autonode,
  label collision policy=hide
]
\end{document}

.