Pressure release valve?

[sauzatime]

Probably should know this since I've owned and used the thing for at least 5 years (at least...)....but I have a travel humi that has a screw for a pressure release valve. Question is, when should I use this thing? Do I need to open it before boarding a plane to prevent a problem, or just if it gets "vacuumed" closed after changes in altitude?

The sticks I'm traveling with now are a little more valuable than they used to be...so suddenly I care how it works. :stretchgr

 

[Volusianator]

I've only used mine if it gets vacuumed shut, but it may be for other purposes as well.

 

[architeuthis]

Only needed if you can't get it opened after a trip...

 

[CWS]

I just open it after I land to release the vacuum. Works better than the old pry with my last nice pen trick.

 

[dpricenator]

After you land or come down from the mountains. I just got mine and have yet to use it, but my 5 stick caddy was tighter than virgin's honeypot when we came down from Big Bear a few months ago.