diff --git a/IBPSA/Fluid/BaseClasses/FlowModels/basicFlowFunction_dp_der.mo b/IBPSA/Fluid/BaseClasses/FlowModels/basicFlowFunction_dp_der.mo
index 8770984d9a..d590d5960c 100644
--- a/IBPSA/Fluid/BaseClasses/FlowModels/basicFlowFunction_dp_der.mo
+++ b/IBPSA/Fluid/BaseClasses/FlowModels/basicFlowFunction_dp_der.mo
@@ -11,7 +11,7 @@ function basicFlowFunction_dp_der
     "Mass flow rate where transition to turbulent flow occurs";
   input Real dp_der
     "Derivative of pressure difference between port_a and port_b (= port_a.p - port_b.p)";
-  output Real m_flow_der(unit="kg/s2")
+  output Real m_flow_der
     "Derivative of mass flow rate in design flow direction";
 protected
   Modelica.Units.SI.PressureDifference dp_turbulent=(m_flow_turbulent/k)^2
diff --git a/IBPSA/Fluid/BaseClasses/FlowModels/basicFlowFunction_dp_der2.mo b/IBPSA/Fluid/BaseClasses/FlowModels/basicFlowFunction_dp_der2.mo
index 596a3c649e..9956b50b24 100644
--- a/IBPSA/Fluid/BaseClasses/FlowModels/basicFlowFunction_dp_der2.mo
+++ b/IBPSA/Fluid/BaseClasses/FlowModels/basicFlowFunction_dp_der2.mo
@@ -39,6 +39,9 @@ IBPSA.Fluid.BaseClasses.FlowModels.basicFlowFunction_dp</a>,
 assuming a constant flow coefficient.
 </p>
 <p>
+When called with <code>dp_der=der(dp)</code> and <code>dp_der2=der(dp_der)</code>, 
+this function returns the second order derivative of <code>m_flow</code> 
+with respect to time.
 When called with <code>dp_der=1</code> and <code>dp_der2=0</code>, 
 this function returns the second order derivative of <code>m_flow</code> 
 with respect to <code>dp</code>.
diff --git a/IBPSA/Fluid/BaseClasses/FlowModels/basicFlowFunction_m_flow_der.mo b/IBPSA/Fluid/BaseClasses/FlowModels/basicFlowFunction_m_flow_der.mo
index cdd5d92e99..8d1b291616 100644
--- a/IBPSA/Fluid/BaseClasses/FlowModels/basicFlowFunction_m_flow_der.mo
+++ b/IBPSA/Fluid/BaseClasses/FlowModels/basicFlowFunction_m_flow_der.mo
@@ -9,7 +9,7 @@ function basicFlowFunction_m_flow_der
     "Flow coefficient, k=m_flow/sqrt(dp), with unit=(kg.m)^(1/2)";
   input Modelica.Units.SI.MassFlowRate m_flow_turbulent(min=0)
     "Mass flow rate where transition to turbulent flow occurs";
-  input Real m_flow_der(unit="kg/s2")
+  input Real m_flow_der
     "Derivative of mass flow rate in design flow direction";
   output Real dp_der
     "Derivative of pressure difference between port_a and port_b (= port_a.p - port_b.p)";
diff --git a/IBPSA/Fluid/BaseClasses/FlowModels/basicFlowFunction_m_flow_der2.mo b/IBPSA/Fluid/BaseClasses/FlowModels/basicFlowFunction_m_flow_der2.mo
index 533b42e215..a5010fea2a 100644
--- a/IBPSA/Fluid/BaseClasses/FlowModels/basicFlowFunction_m_flow_der2.mo
+++ b/IBPSA/Fluid/BaseClasses/FlowModels/basicFlowFunction_m_flow_der2.mo
@@ -9,9 +9,9 @@ function basicFlowFunction_m_flow_der2
     "Flow coefficient, k=m_flow/sqrt(dp), with unit=(kg.m)^(1/2)";
   input Modelica.Units.SI.MassFlowRate m_flow_turbulent(min=0)
     "Mass flow rate where transition to turbulent flow occurs";
-  input Real m_flow_der(unit="kg/s2")
+  input Real m_flow_der
     "1st derivative of mass flow rate in design flow direction";
-  input Real m_flow_der2(unit="kg/s3")
+  input Real m_flow_der2
     "2nd derivative of mass flow rate in design flow direction";
   output Real dp_der2
     "2nd derivative of pressure difference between port_a and port_b (= port_a.p - port_b.p)";
@@ -39,6 +39,9 @@ IBPSA.Fluid.BaseClasses.FlowModels.basicFlowFunction_m_flow</a>,
 assuming a constant flow coefficient.
 </p>
 <p>
+When called with <code>m_flow_der=der(m_flow)</code> and <code>m_flow_der2=der(m_flow_der)</code>, 
+this function returns the second order derivative of <code>dp</code> 
+with respect to time.
 When called with <code>m_flow_der=1</code> and <code>m_flow_der2=0</code>, 
 this function returns the second order derivative of <code>dp</code> 
 with respect to <code>m_flow</code>.