Which gas is typically used in purging to minimize fire risk?

Nitrogen is commonly used in purging applications to minimize fire risk due to its inert properties. As an inert gas, nitrogen does not support combustion and helps to displace oxygen in the atmosphere of the equipment or area being purged. This reduction in oxygen levels significantly decreases the potential for a fire or explosion, making nitrogen an effective fire-safety measure in various industrial processes, such as in tanks or pipelines that contain flammable materials.

In contrast, gases like oxygen can enhance combustion and increase fire risk, while helium, although inert, is not typically used in purging for this specific purpose due to its higher cost compared to nitrogen. Carbon dioxide is often used in fire suppression systems and can displace oxygen, but its application is generally more focused on extinguishing fires rather than purging for fire prevention. Therefore, nitrogen's effectiveness and cost-efficiency position it as the preferred choice for purging to mitigate fire hazards.