In a recent discussion regarding an accident with a Fuel-Oxy Torch system, I had some discussions about the layers of protection and the Prevent-Protect-Mitigate safety model using the Hierarchy of Controls (Elimination, Substitution, Engineering Controls, Administrative Controls, and PPE). The event did NOT involve a flash-back, but I used the flash-back requirements to demonstrate the difference in these layers of protection.
To give it away… flash-back arrestors do NOT prevent the flash-back event; they PROTECT (and some may say they MITIGATE) the event from escalating to serious consequences.