What process involves quickly opening and closing a welding tank's valve to clean out debris?

The process of quickly opening and closing a welding tank's valve to clean out debris is known as cracking. This technique allows for a brief release of gas from the tank, which can help to dislodge and expel any contaminants that may be obstructing the valve or hose. By momentarily cracking the valve, the sudden burst of gas can push out debris without requiring the tank to be fully opened, thereby maintaining a safer environment by minimizing the risk of excessive gas release.

Other techniques listed serve different purposes in gas management or maintenance. For example, purging usually involves removing unwanted gases from a system, which may include a more thorough process than simply cracking the valve. Blowing generally refers to using compressed air to clean or clear out systems but isn't specifically about manipulating gas valves. Flushing typically involves using a liquid to clear a system of impurities or debris, which is not relevant to the action described in the question.