diff --git a/src/Mod/Fem/femguiobjects/_ViewProviderFemElementFluid1D.py b/src/Mod/Fem/femguiobjects/_ViewProviderFemElementFluid1D.py
index c262aea5ea..1c42cc8608 100644
--- a/src/Mod/Fem/femguiobjects/_ViewProviderFemElementFluid1D.py
+++ b/src/Mod/Fem/femguiobjects/_ViewProviderFemElementFluid1D.py
@@ -277,6 +277,7 @@ class _TaskPanelFemElementFluid1D:
             QtCore.SIGNAL("cellChanged(int, int)"),
             self.pump_characteristics_changed
         )
+        # some fluid types deactivated since they are not implemented in ccx writer
         self.parameterWidget.cb_section_type.addItems(
             _FemElementFluid1D._FemElementFluid1D.known_fluid_types
         )
diff --git a/src/Mod/Fem/femobjects/_FemElementFluid1D.py b/src/Mod/Fem/femobjects/_FemElementFluid1D.py
index c37a0c58db..9ab3498cc9 100644
--- a/src/Mod/Fem/femobjects/_FemElementFluid1D.py
+++ b/src/Mod/Fem/femobjects/_FemElementFluid1D.py
@@ -33,7 +33,9 @@ __url__ = "http://www.freecadweb.org"
 class _FemElementFluid1D:
     "The FemElementFluid1D object"
 
-    known_fluid_types = ['Liquid', 'Gas', 'Open Channel']
+    known_fluid_types = ['Liquid']
+    # 'Gas', 'Open Channel' are not impemented in ccx writer
+    # known_fluid_types = ['Liquid', 'Gas', 'Open Channel']
     known_liquid_types = [
         'PIPE MANNING',
         'PIPE ENLARGEMENT',
diff --git a/src/Mod/Fem/femsolver/calculix/writer.py b/src/Mod/Fem/femsolver/calculix/writer.py
index ec1f42c213..0b94f61e10 100644
--- a/src/Mod/Fem/femsolver/calculix/writer.py
+++ b/src/Mod/Fem/femsolver/calculix/writer.py
@@ -817,10 +817,14 @@ class FemInputWriterCcx(writerbase.FemInputWriter):
                             material
                         )
                         section_geo = liquid_section_def(fluidsec_obj, section_type)
+                    '''
+                    # deactivate as it would result in section_def and section_geo not defined
+                    # deactivated in the App and Gui object and thus in the task panel as well
                     elif fluidsec_obj.SectionType == 'Gas':
                         section_type = fluidsec_obj.GasSectionType
                     elif fluidsec_obj.SectionType == 'Open Channel':
                         section_type = fluidsec_obj.ChannelSectionType
+                    '''
                     f.write(section_def)
                     f.write(section_geo)
                 elif 'shellthickness_obj'in ccx_elset:  # shell mesh