As a former firefighter, I can tell you that in the right hands, a proper sized (10 lb) fire extinguisher can be a very effective tool.

All tools regardless of their usage, require proper training and know-how. You may not have this knowledge, however others do and you never know who is going to be with you or close by when the time comes to effectively utilize that tool.

That being said, there is also a fine line in trying to contain a fire and knowing when to get out to save your own life or more importantly other people's lifes.

Some fire departments offer basic training for the public in using fire extinguishers etc. It may be worth your time to check with your local fire department.