From f8045d83c64de122ff3ed310fa84cfbaede2423f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Juan=20Jos=C3=A9=20G=C3=B3mez=20Romera?=
 <jjgomera@gmail.com>
Date: Thu, 21 Nov 2024 22:09:32 +0100
Subject: [PATCH] Fix bug #76, bad vapor quality definition in region_3 below
 the critical point

---
 iapws/iapws97.py | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/iapws/iapws97.py b/iapws/iapws97.py
index eff5f99..c6b1dba 100644
--- a/iapws/iapws97.py
+++ b/iapws/iapws97.py
@@ -1685,10 +1685,13 @@ def _Region3(rho, T):
     propiedades["alfav"] = (gd - Tr * gdt) / (2 * gd + d * gdd) / T
     propiedades["kt"] = 1 / (2 * d * gd + d ** 2 * gdd) / rho / R / T * 1000
     propiedades["region"] = 3
+
+    propiedades["x"] = 1
     if T < Tc and propiedades["P"] < Pc:
-        propiedades["x"] = 0
-    else:
-        propiedades["x"] = 1
+        t_sat = _TSat_P(propiedades["P"])
+        if T < t_sat:
+            propiedades["x"] = 0
+
     return propiedades