As long as they aren't a private department... volunteer fire departments are usually more friendly because, well, they're maintained through a community effort. They're made up of the community, and their duty is to serve the community. Privately funded departments won't always be as nice... I was in Troy, NY filming their STH-10A (which failed) and a guy came up to me and basically told me to get out because apparently I was in a private parking space even though it didn't say anything about it. So maybe check if it's a volunteer fire department before you go knocking on their door about a rusty old chimney vent.
"Someday soon we'll stop to ponder what on earth's this spell we're under...
We made the grade and still we wonder who the hell we are..."
-Styx, from The Grand Illusion