Index: firmware/App/Modes/BloodPrime.c
===================================================================
diff -u -r1a36e9bd718b40ceaee21dd12eca2da353828e30 -rf3d625e2593ced120c4a98b9ed7e28b132445642
--- firmware/App/Modes/BloodPrime.c	(.../BloodPrime.c)	(revision 1a36e9bd718b40ceaee21dd12eca2da353828e30)
+++ firmware/App/Modes/BloodPrime.c	(.../BloodPrime.c)	(revision f3d625e2593ced120c4a98b9ed7e28b132445642)
@@ -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 };
 
@@ -151,12 +153,12 @@
  * @brief
  * The resetBloodPrimeFlags function resets the blood prime request flags.
  * @details Inputs: none
- * @details Outputs: Blood prime request flags reset to FALSE.
+ * @details Outputs: Blood prime request flags reset.
  * @return none
  *************************************************************************/
 static void resetBloodPrimeFlags( void )
 {
-    // No flags for now
+    airTrapFillInProgress = isAirTrapFillInProgress();
 }
 
 /*********************************************************************//**
@@ -227,6 +229,22 @@
         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_CLOSED_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 +254,11 @@
         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 );