I went Black Bear Hunting Last year (2009) I couldnt buy Bear spray. I guess a small fire extingquiser would work..
WRONG!!!
Not ridiculing you here, Bear spray is not a casual item that if you see a bear, you spray it and the bear simply looks at you and says OK, Ill go the other way. Bear spray is typicly only used as a final deterant to a most likley "Charging bear," and a fire extunguisher will in no way turn back a bear. They encounter much worse that that with a skunk, and with bees getting into a honey hive and they just keep lumbering along.
Most bears (when out on the trail) you will never see. Be thankful... and if you do, and you're close enough to trigger an encounter. DO NOT RUN. this will only insure it pursuing you.
If you happen to encounter a bear by surprise, and trip their the fight responce. Most likley they will charge you first, and then stop. and wait for a reaaction.
Remember that you are a strange thing to them that they dont normally encounter.
If they do charge, Stand your ground, Make yourself as large as you can, and make alot of noise while backing away away slowly.
Your can of bear spray will be labled with its "effective range" KNOW THIS !!
It wont serve you any good when you panic and pull the trigger before the bear is in "effective range". You will run out of spray, and now you have an extreamly irritated bear, but not detered. and you are now in his sights.
all the best..