Index: firmware/App/Controllers/AirTrap.c
===================================================================
diff -u -r736cc5b56cc9c784ab1d8fc8687a73d190c35759 -rb4337dc5afaca148dd23c0c4021875563b565739
--- firmware/App/Controllers/AirTrap.c	(.../AirTrap.c)	(revision 736cc5b56cc9c784ab1d8fc8687a73d190c35759)
+++ firmware/App/Controllers/AirTrap.c	(.../AirTrap.c)	(revision b4337dc5afaca148dd23c0c4021875563b565739)
@@ -74,6 +74,8 @@
 
 static U32 airPumpUpperLevelCtr = 0;                                                        ///< Timer count for air pump persistence.
 
+static BOOL airTrapValveOpenAtStablePressureState = FALSE;                                  ///< AirTrap valve open at every 15 minutes of pressure stable state, to clear any any accumulated bubbles
+
 // ********** private function prototypes **********
 
 static AIR_TRAP_STATE_T handleAirTrapManualControlState( void );
@@ -93,8 +95,9 @@
     U32 i;
 
     resetAirTrap();
-    airTrapDataPublicationTimerCounter = DATA_PUBLISH_COUNTER_START_COUNT;
-    airPumpUpperLevelCtr               = 0;
+    airTrapDataPublicationTimerCounter      = DATA_PUBLISH_COUNTER_START_COUNT;
+    airPumpUpperLevelCtr                    = 0;
+    airTrapValveOpenAtStablePressureState   = TRUE;
 
     for ( i = 0; i < NUM_OF_AIR_TRAP_LEVEL_SENSORS; i++ )
     {
@@ -156,6 +159,19 @@
 
 /*********************************************************************//**
  * @brief
+ * The signalAirTrapValveOpen function sets the flag to open up air trap valve.
+ * @details Inputs: airTrapValveOpenAtStablePressureState
+ * @details Outputs: airTrapValveOpenAtStablePressureState
+ * @return none
+ *************************************************************************/
+void signalAirTrapValveOpen( void )
+{
+    // Open air trap valve
+    airTrapValveOpenAtStablePressureState = TRUE;
+}
+
+/*********************************************************************//**
+ * @brief
  * The isAirTrapControlling function determines whether the air trap is
  * currently controlling.
  * @details Inputs: airTrapControllerState
@@ -331,6 +347,21 @@
         }
     }
 
+    //Open valve every 15 mins once during pressure stable state
+    else if ( TRUE == airTrapValveOpenAtStablePressureState )
+    {
+        airTrapValveOpenAtStablePressureState = FALSE;
+        if ( AIR_PUMP_STATE_ON == getAirPumpState() )
+        {
+            setAirPumpState( AIR_PUMP_STATE_OFF );
+        }
+
+        setValveAirTrap( STATE_OPEN );
+        fillStartTime = getMSTimerCount();
+        SEND_EVENT_WITH_2_U32_DATA( HD_EVENT_AIR_TRAP_FILL, STATE_CLOSED, 0 );
+        result = AIR_TRAP_VALVE_OPEN_STATE;
+    }
+
     //Turn on air pump if fluid reaches upper level.
     else if ( AIR_TRAP_LEVEL_FLUID == getAirTrapLevel( AIR_TRAP_LEVEL_SENSOR_UPPER ) )
     {
@@ -392,8 +423,8 @@
         pendingStopAirTrapController = FALSE;
         result = AIR_TRAP_MANUAL_CONTROL_STATE;
     }
-    // Transition to closed valve state when fluid detected at lower level
-    else if ( AIR_TRAP_LEVEL_FLUID == getAirTrapLevel( AIR_TRAP_LEVEL_SENSOR_LOWER ) )
+    // Transition to closed valve state when fluid detected at upper level
+    else if ( AIR_TRAP_LEVEL_FLUID == getAirTrapLevel( AIR_TRAP_LEVEL_SENSOR_UPPER ) )
     {
         setValveAirTrap( STATE_CLOSED );
         result = AIR_TRAP_VALVE_CLOSED_STATE;