Index: firmware/App/Modes/BloodPrime.c
===================================================================
diff -u -rd963f2a611b2d5ed18172c390b0f593045abced7 -r8d3dbd25627fb7e993409eb47b2575e0430afddd
--- firmware/App/Modes/BloodPrime.c	(.../BloodPrime.c)	(revision d963f2a611b2d5ed18172c390b0f593045abced7)
+++ firmware/App/Modes/BloodPrime.c	(.../BloodPrime.c)	(revision 8d3dbd25627fb7e993409eb47b2575e0430afddd)
@@ -61,6 +61,8 @@
 static U32  bloodPrimeRampControlTimerCtr;                                      ///< Timer counter for determining interval for controlling BP ramp.
 static U32  bloodPrimePublishTimerCtr;                                          ///< Timer counter for determining interval for blood prime status to be published.
 
+static BOOL airTrapFillInProgress;                                              ///< Flag indicates an air trap fill is in progress.
+
 /// Interval (in task intervals) at which to publish blood prime data to CAN bus.
 static OVERRIDE_U32_T bloodPrimePublishInterval = { BLOOD_PRIME_DATA_PUBLISH_INTERVAL, BLOOD_PRIME_DATA_PUBLISH_INTERVAL, BLOOD_PRIME_DATA_PUBLISH_INTERVAL, 0 };
 
@@ -126,21 +128,35 @@
     setValvePosition( VDI, VALVE_POSITION_C_CLOSE );
     setValvePosition( VDO, VALVE_POSITION_C_CLOSE );
     setValvePosition( VBA, VALVE_POSITION_B_OPEN );
-    setValvePosition( VBV, VALVE_POSITION_B_OPEN );
 
     // Ensure dialysate outlet and Heparin pumps are stopped
     signalDialOutPumpHardStop();
     stopSyringePump();
 
     // start blood and dialysate inlet pumps
-    setBloodPumpTargetFlowRate( (U32)bloodPrimeRampFlowRate_mL_min, MOTOR_DIR_FORWARD, PUMP_CONTROL_MODE_OPEN_LOOP );
     setDialInPumpTargetFlowRate( DIALYSATE_FLOW_RATE_FOR_RECIRC, MOTOR_DIR_FORWARD, PUMP_CONTROL_MODE_CLOSED_LOOP );
     cmdStartDGTrimmerHeater();
     setCurrentSubState( (U32)bloodPrimeState );
 
     // Start air trap control
     startAirTrapControl();
 
+    // make sure air trap fill is handled right
+    if ( TRUE == isAirTrapFillInProgress() )
+    {
+        // set BP to air trap fill rate if air trap fill has been initiated
+        setBloodPumpTargetFlowRate( AIR_TRAP_FILL_BLOOD_FLOW_RATE, MOTOR_DIR_FORWARD, PUMP_CONTROL_MODE_OPEN_LOOP );
+        // close VBV for fill
+        setValvePosition( VBV, VALVE_POSITION_C_CLOSE );
+    }
+    else
+    {
+        // Start blood pump at prescribed flow rate
+        setBloodPumpTargetFlowRate( (U32)bloodPrimeRampFlowRate_mL_min, MOTOR_DIR_FORWARD, PUMP_CONTROL_MODE_OPEN_LOOP );
+        // re-open VBV for blood recirculation
+        setValvePosition( VBV, VALVE_POSITION_B_OPEN );
+    }
+
     // Set user alarm recovery actions allowed in this sub-mode
     setAlarmUserActionEnabled( ALARM_USER_ACTION_RESUME, TRUE );
     setAlarmUserActionEnabled( ALARM_USER_ACTION_RINSEBACK, TRUE );
@@ -151,12 +167,12 @@
  * @brief
  * The resetBloodPrimeFlags function resets the blood prime request flags.
  * @details Inputs: none
- * @details Outputs: Blood prime request flags reset to FALSE.
+ * @details Outputs: airTrapFillInProgress
  * @return none
  *************************************************************************/
 static void resetBloodPrimeFlags( void )
 {
-    // No flags for now
+    airTrapFillInProgress = isAirTrapFillInProgress();
 }
 
 /*********************************************************************//**
@@ -210,8 +226,9 @@
  * @brief
  * The handleBloodPrimeRampState function handles the blood prime ramp
  * state operations.
- * @details Inputs: flags
- * @details Outputs: flags handled
+ * @details Inputs: bloodPrimeTargetVolume_mL, airTrapFillInProgress,
+ * bloodPrimeRampControlTimerCtr
+ * @details Outputs: cumulativeBloodPrimeVolume_mL, bloodPrimeRampControlTimerCtr
  * @return next blood prime state
  *************************************************************************/
 static BLOOD_PRIME_STATE_T handleBloodPrimeRampState( void )
@@ -227,6 +244,22 @@
         cumulativeBloodPrimeVolume_mL.data = bloodPrimeTargetVolume_mL;
     }
 
+    // if an air trap fill has started, set BP rate and VBV state accordingly
+    if ( ( airTrapFillInProgress != TRUE ) && ( TRUE == isAirTrapFillInProgress() ) )
+    {
+        // set BP to air trap fill rate if air trap fill has been initiated
+        setBloodPumpTargetFlowRate( AIR_TRAP_FILL_BLOOD_FLOW_RATE, MOTOR_DIR_FORWARD, PUMP_CONTROL_MODE_OPEN_LOOP );
+        // close VBV for fill
+        setValvePosition( VBV, VALVE_POSITION_C_CLOSE );
+    }
+    // if an air trap fill has completed, restore BP and VBV to blood prime ramp settings
+    else if ( ( TRUE == airTrapFillInProgress ) && ( isAirTrapFillInProgress() != TRUE ) )
+    {
+        // re-open VBV after fill
+        setValvePosition( VBV, VALVE_POSITION_B_OPEN );
+        // Blood pump rate will be set to ramp rate below
+    }
+
     // Has blood prime completed?
     if ( getBloodPrimeVolume() >= bloodPrimeTargetVolume_mL )
     {
@@ -236,13 +269,11 @@
         signalBloodPrimeToDialysis();   // Signal treatment mode that it's time to start dialysis
         cmdStopDGTrimmerHeater();       // Stop trimmer heater - dialysis sub-mode will restart as appropriate
     }
-    else
+    else if ( isAirTrapFillInProgress() != TRUE )
     {
         // ramp blood pump on ramp interval
         if ( ++bloodPrimeRampControlTimerCtr >= BLOOD_PRIME_RAMPING_INTERVAL )
         {
-            U32 setBPRate = getTreatmentParameterU32( TREATMENT_PARAM_BLOOD_FLOW );
-
             bloodPrimeRampControlTimerCtr = 0;
             bloodPrimeRampFlowRate_mL_min += bloodPrimeRampStep_mL;
             setBloodPumpTargetFlowRate( (U32)bloodPrimeRampFlowRate_mL_min, MOTOR_DIR_FORWARD, PUMP_CONTROL_MODE_OPEN_LOOP );