Please could you let me know why foam extinguishers are less effective than AFFF ones. What are the differences in the contents?

Many thanks.

NB. I work for the Kennet & Avon Canal Trust, we have to carry AFFF on our passenger trip boats.

As far as I am aware, non AFFF foam extinguishers are not less effective than AFFF and have similar ratings, but they do have different qualities. For instance AFFF is less environmentally friendly than some however it flows easily therefore has a more rapid knockdown capability. For me it all depends on the type of fires you wish to deal with and somebody has decided AFFF is the best for your situation.

You say you work for the Kennet & Avon Canal Trust and have to carry AFFF on our passenger trip boats but what is this requirement based on. The only guide I could find was Boat Safety Scheme and chapter six fire extinguishers, only refers to rating not type of foam you need to find out which guidance they use.

Check out http://en.wikipedia....e_fighting_foam and http://www.firesafe....uisher-general/ may be useful.

(Thinking out loud) It may be that if you use powder you will disappear in a giant cloud which may "worry" your passengers, some local authorities are now banning dry powder extinguishers for this reason and the fact of the "mess" they make. Also AFFF foam is very common for foam extinguishers.