Index: firmware/App/Controllers/PresOccl.c
===================================================================
diff -u -re4cc37257141c5227186ac6d8ca3d6c87d009042 -ref4eed270f61b2fe2eca37b5c253b33f11629c12
--- firmware/App/Controllers/PresOccl.c	(.../PresOccl.c)	(revision e4cc37257141c5227186ac6d8ca3d6c87d009042)
+++ firmware/App/Controllers/PresOccl.c	(.../PresOccl.c)	(revision ef4eed270f61b2fe2eca37b5c253b33f11629c12)
@@ -581,13 +581,17 @@
 
 #ifndef DISABLE_PRESSURE_CHECKS
         // Cannot monitor for low venous pressure while venting air trap
-        if ( STATE_OPEN == getValveAirTrapStatus() )
+        if ( getValveAirTrapStatus() != STATE_OPEN )
         {
             if ( TRUE == isPersistentAlarmTriggered( ALARM_ID_VENOUS_PRESSURE_LOW, venPres < venLowLimit ) )
             {
                 SET_ALARM_WITH_2_F32_DATA( ALARM_ID_VENOUS_PRESSURE_LOW, venPres, venLowLimit );
             }
         }
+        else
+        {   // clear persistence if air trap valve is open
+            isPersistentAlarmTriggered( ALARM_ID_VENOUS_PRESSURE_LOW, FALSE );
+        }
 
         if ( TRUE == isPersistentAlarmConditionCleared( ALARM_ID_VENOUS_PRESSURE_LOW, venPres < venLowLimit ) )
         {