What type of air supply is used in the Scott Air-Pak X3 SCBA system?

The correct answer is that the Scott Air-Pak X3 SCBA system utilizes compressed breathing air. This type of air supply is specifically designed for respiratory protection in hazardous environments, allowing users to breathe safely while performing tasks in low-oxygen or contaminated atmospheres.

Compressed breathing air is filtered and stored in high-pressure cylinders, ensuring it is clean and suitable for inhalation. This is essential for fire service operations or industrial applications, where the air quality may be compromised. The SCBA system is engineered to deliver this air efficiently to the wearer's mask, facilitating sustained oxygen supply during strenuous activities.

Other options such as liquid oxygen or regular atmospheric air do not provide the required level of protection and safety that the compressed breathing air does. Liquid oxygen, while it can be a source of oxygen, is not practical for SCBA applications due to its storage and handling complexities. Regular atmospheric air can contain harmful contaminants or insufficient oxygen levels, which makes it unsuitable for use in protective gear like the Scott Air-Pak X3. Helium-based air, although sometimes used in specialized applications, does not meet the standards required for safe breathing in emergencies, further underscoring the importance of using compressed breathing air for these systems.