There is someone who goes to FMCA rallies whom I seriously respect when it comes to fire extinguishers.. he's known as MAC The Fire Guy
He also has a web presence.. Google him, Listen to his advice,. Buy from him (or another supplier) but buy the type he tells you to buy.
Have seen his demonstrations.. Man knows his stuff, Have also seen professional firemen (Which he used to be) demonstarte.. Mac knows his stuff.
Home is where I park it!