Why should the valve of an emergency oxygen system be cracked slightly before attaching the regulator?

Cracking the valve of an emergency oxygen system slightly before attaching the regulator serves an important purpose in ensuring the proper functioning and safety of the system. By doing so, you are allowing any foreign matter or debris that may be present in the valve or the system to be expelled. This action helps to clear the connection and ensures that the oxygen flowing into the regulator is clean and free from contaminants.

Any foreign particles could potentially clog the regulator or interfere with the delivery of oxygen, which could have serious implications in an emergency situation. By releasing the pressure momentarily and forcing any debris out, the integrity of the oxygen system is maintained, promoting reliable and safe operations.

Creating a vacuum, ensuring maximum pressure, or ventilating the system are not the primary concerns associated with this action. The focus is specifically on ensuring that the oxygen delivered is as clean as possible for safe use in emergency scenarios.