diff --git a/TBF/BenchControl/Sequences/MainSeqUtils.cs b/TBF/BenchControl/Sequences/MainSeqUtils.cs
index 39c10d36a..590bdc7b5 100644
--- a/TBF/BenchControl/Sequences/MainSeqUtils.cs
+++ b/TBF/BenchControl/Sequences/MainSeqUtils.cs
@@ -493,9 +493,9 @@ namespace TBF.BenchControl.Sequences
                 }
 
                 /// Tank emptying valves states
-                bool draining1 = (StateMachine.DrainValve1 != null);
-                bool draining2 = (StateMachine.DrainValve2 != null);
-                bool draining3 = (StateMachine.DrainValve3 != null);
+                bool draining1 = (StateMachine.DrainValve1 != null && StateMachine.Tank1 != null);
+                bool draining2 = (StateMachine.DrainValve2 != null && StateMachine.Tank2 != null);
+                bool draining3 = (StateMachine.DrainValve3 != null && StateMachine.Tank3 != null);
 
                 int drainingStartTime = StateMachine.Time;
 
@@ -517,9 +517,9 @@ namespace TBF.BenchControl.Sequences
                         .EnterState();
                     while (StateMachine.WaitRunDevsRunOps().Contains(Event.Busy)) { }
 
-                    if (draining1 && StateMachine.Tank1.IsEmpty()) draining1 = false;
-                    if (draining2 && StateMachine.Tank2.IsEmpty()) draining2 = false;
-                    if (draining3 && StateMachine.Tank3.IsEmpty()) draining3 = false;
+                    if (draining1 && StateMachine.Tank1 != null && StateMachine.Tank1.IsEmpty()) draining1 = false;
+                    if (draining2 && StateMachine.Tank2 != null && StateMachine.Tank2.IsEmpty()) draining2 = false;
+                    if (draining3 && StateMachine.Tank3 != null && StateMachine.Tank3.IsEmpty()) draining3 = false;
                 }
 
                 /// Close all drain valves