What is the most effective firefighting technique when dealing with liquid oxygen?

The most effective firefighting technique when dealing with liquid oxygen involves applying water to the area until the leak freezes and is sealed. This approach works because liquid oxygen is extremely cold (around -183°C or -297°F) and can cause significant hazards if it leaks. By introducing water to the leak, the water freezes upon contact due to the extremely low temperatures of the liquid oxygen, creating an ice seal that can effectively contain the leak. This method minimizes the risk of oxygen-rich environments that could lead to explosive combustion.

Using water in this way also helps to cool surrounding areas that may be exposed to the oxygen, effectively reducing fire risks and preventing potential ignition sources from igniting the oxygen. It's crucial to manage the situation carefully to ensure that the surrounding materials do not ignite due to increased oxygen concentration, which enhances the fire risk.

The other options present less effective strategies for dealing with liquid oxygen. Smothering until the leak is sealed may not work, as liquid oxygen can greatly enhance combustion and merely covering the area might not mitigate the danger. Removing leading tanks might disrupt operations but could also create further risks. Waiting for the liquid oxygen to vaporize ignores the immediate hazards presented by localized concentrations of oxygen, potentially leading to dangerous conditions if not managed promptly.