diff --git a/thermosteam/_phase.py b/thermosteam/_phase.py
index ce903588..71f369c5 100644
--- a/thermosteam/_phase.py
+++ b/thermosteam/_phase.py
@@ -19,7 +19,7 @@
     'S': 'SOLID',
     'L': 'LIQUID',
 }
-index = {j: i for i,j in enumerate(valid_phases)}
+index = {j: i for i,j in enumerate(sorted(valid_phases))}
 
 def check_phase(phase):
     """
@@ -38,7 +38,8 @@ def check_phase(phase):
         raise RuntimeError(
             f"invalid phase {repr(phase)} encountered; valid phases are "
             "'s' (solid), 'l' (liquid), 'g' (gas), 'S' (SOLID), and 'L' (LIQUID)"
-        )  
+        )
+    return phase
 
 def phase_tuple(phases):
     """
diff --git a/thermosteam/indexer.py b/thermosteam/indexer.py
index f465c8be..2391b7a1 100644
--- a/thermosteam/indexer.py
+++ b/thermosteam/indexer.py
@@ -1320,17 +1320,19 @@ def group_vol_composition(self):
 def by_mass(self):
     """Return a ChemicalMassFlowIndexer that references this object's molar data."""
     try:
-        mass = self._data_cache['mass']
+        mass = self._data_cache['mass', self._phase]
     except:
         chemicals = self.chemicals
-        self._data_cache['mass'] = mass = \
+        self._data_cache['mass', self._phase] = mass = \
         ChemicalMassFlowIndexer.from_data(
             SparseVector.from_dict(
                 MassFlowDict(self.data.dct, chemicals.MW),
                 chemicals.size
             ),
-            self._phase, chemicals,
-            False
+            self._phase, 
+            chemicals,
+            False,
+            True,
         )
     return mass
 ChemicalMolarFlowIndexer.by_mass = by_mass
@@ -1367,12 +1369,12 @@ def by_volume(self, TP):
     
     """
     try:
-        vol = self._data_cache['vol', TP]
+        vol = self._data_cache['vol', TP, self._phase]
     except:
         chemicals = self._chemicals
         V = [i.V for i in chemicals]
         phase = self._phase
-        self._data_cache['vol', TP] = \
+        self._data_cache['vol', TP, self._phase] = \
         vol = ChemicalVolumetricFlowIndexer.from_data(
             SparseVector.from_dict(
                 VolumetricFlowDict(self.data.dct, TP, V, None, self, {}),