Associate Editor Kylie Wroblaski at Buildings.com posted a good article about Fire Doors:
Take note of the other posts on Fire Doors to see how they play in your theatre.
Make a pre-emptive strike against the spread of smoke and fire by keeping all fire doors closed and latched unless you are moving equipment or personnel through the door. Do not prop fire doors open with chairs, microphone stands, stage weights, flag poles, desks, speakers, pianos, boxes, backpacks, wedges, flip-down props / stops, or by tying the handle to a nearby railing or wall. If the door cannot close and latch on it's own, then it must be repaired.