Why should the valve on the oxygen system be cracked before attaching the regulator?

Cracking the valve on the oxygen system before attaching the regulator serves the important purpose of expelling foreign matter from the outlet port. When a gas cylinder is manufactured and maintained, dust or debris can accumulate at the outlet. By briefly opening the valve, any contaminants are released, ensuring that the connection to the regulator is clean and free from blockages. This step is critical in maintaining the integrity of the oxygen delivery system, promoting safety and effectiveness in its use.

Other options do not directly address the immediate concern of ensuring the outlet port is clean. While letting oxygen flow freely can be beneficial for the operation of the system, it does not specifically ensure cleanliness. Relieving pressure in the cylinder is irrelevant when attaching a regulator, as the cylinder is designed to maintain pressure until a proper connection is made. Similarly, while preventing gas leaks is an important safety measure, cracking the valve primarily addresses contamination rather than sealing issues.