I once worked for a company that gave a "fire emergency kit" to every traveling employee consisting (1) an explosion-proof 2 D-cell flashlight and (2) a 4 lb roll of industrial strength masking tape and other goofy stuff. One of my workmates actually carried it all (about 6-8lb) in his briefcase on every trip. I use a very wet towel to seal the any room doors on occasion.

MisterNice