Does the valve on a pelican case need to have anything done to it, or does it work on its own? Maybe its a silly question, but I'm flying with it for the first time, and they guy that sold it to me said this valve would come in handy when I'm flying. Great, but I don't know if I'm supposed to know how to operate the valve or if it handles the situation on its own, allowing me to open the case easily after flying. Thanks for your help!