Martin-123

Hello, I'm doing research for novel firefighting equipment and can't be too specific about the application, I'm sorry. My issue is the weight of the hose, and its contents, when in use. I need it to be as light as possible. I understand AFF is a mixture of chemicals and water, and that there are low, medium and high expansion foams. Can anyone please advise... Is the expansion due to a chemical reaction (if so, what's the gas released?) or just due to the mechanical effects of being mixed and then jettisoned from a nozzle? Where does the 'mixing' between chemicals & water, and crucially, where does the 'expansion' take place? I see three possibilities for the mixing... Is AFF stored ready-mixed, in a tank? In which case, when/where does the expansion take place? Is it stored, expanded, in the tank? ... does it expand in the hose after release from the tank? ... does it expand on release from the nozzle? Are the water and chemicals stored separately and mixed just prior to entering the hose, where the expansion takes place ... or (again) on release from the nozzle? Are the water and chemicals fed in separate hoses and mixed in the nozzle? Very grateful for any contributions. Martin

Thank you, Harry and AnthonyB, Both very helpful responses. Excellent. I now have another post, perhaps you'd look at... Thank you again. Martin

Hello, There's a great deal of material on the internet about the toxicity to the environment of AFFs, but very little (none, that I can find), about the consequences of spraying it directly onto people. My question is, in a scenario where people are under direct threat of burning, like in an aircraft fire, is it ok to spray them with large quantities of AFF or would that cause them to die of drowning or suffocation...? ... or indeed to die later as a consequence of the exposure to toxic chemicals? Many thanks for any contributions...

Excellent. Thank you, Anthony. I will make sure my manager knows this...!

Hello All, It's good to be a part of this fire safety forum. Alongside my desk at work, is a fire evacuation route for an adjacent room. The route is well over a meter wide, but it has become a bit of a dumping ground for old office chairs and big cardboard boxes from computer deliveries. Even taking these obstacles into account, the route which is free of obstacles is still probably over a meter wide. However, as the chairs are on castors, and the boxes aren't fixed to anything, they could easily be pushed into the route in the event of an evacuation. I have drawn all this to the attention of my Manager, but he's not dealing with it with any urgency. I'd like to put the pressure on him by pointing out that blocking a fire exit, or putting obstacles in a place where they could become hazardous in an evacuation, is a criminal offence. Would I be right to say that? Can anyone supply a reference or a link which I could send to him, please? Many thanks in advance, for any help here.