Douglas,
I could not locate a soda-pop can, but did try a can per the info you provided. It works great! Definitely better than the diaphram pump in that it can more easily be carried from roof to hood area. I would like to see your set-up, but you are hard to reach since you are surrounded by a wall of forest fire on every side and we are forced to use alternate route.
I don't know anything about someone skulking around your premises. Couldn't be me. If I happened to be at the post office and just happened to see your white van 5 or 6 houses south, parked alongside just in front of your shop, with hundreds of extinguishers waiting to be serviced, I certainly would not approach - especially with all those attack squirrels about. Nope - not me. My hands are clean.
Richard