A flashback is defined as a flame traveling almost instantaneously in the opposite direction to the normal gas-flow. A flashback incident can cause irreparable damage to equipment and can, in a worst case scenario, be catastrophic if the flash enters the gas cylinder resulting in an explosion. Back-feeding of gas flames can be a result of various incidents of which incorrect closing-down of equipment, pressure drop, incorrect igniting procedure and excessive pressure to name but a few. Flashback arrestors are safety enhancing items which ensure gas-flow in one direction only. Any brazing, heating, gas welding or cutting operation should not be done without flashback arrestors being fitted to both regulators and torch.