We only have one grass rig with CAFS so it's not my immediate thought. When I looked at the link SFD_E73_RET posted my knee jerk thought was that it completely wasted an entire compartment. Of course, then I realized the CAFS unit such as that one takes up the same amount, or less, than a standard tank and pump so you could make up the space difference in another area.
If it works for you then go for it. I agree a SCBA cylinder would be better than a SCUBA cylinder because we have them on the trucks. Out of curiosity, what does it take to recharge the unit in case you use the entire amount and need more? Only asking because I'm not familiar with this style.
How much will a setup like in the photo cost to have installed in a rescue apparatus ?
Brother - a couple of observations from a "geezer" in the fire service. On this forum there are probably 1,000 years of apparatus design, purchase, use and experience. I, personally, have been in the fire service for 49 years, and in apparatus sales for over 30. There are some extremely smart people who read and respond on this blog - most have forgotten more about apparatus than I ever dreamed of knowing. So- a little advice (or an impartation of wisdom - depending on how you look at it)
When you ask a question such as yours, put out some facts - you will learn that opinions based on fact are much more valuable than strict opinions.
What are the demographics of your department - 300 runs a year, 20, 3000? Are you rural or metro - or surbaban? Do you run interstate? Have a major highway with 30-40,000 cars per day? Is extricating "bubba" from a hay baler qualify for call of the year or is an overturned semi with 20+ vehicles involved not all that unlikely?
Again - the expertise and wisdom on this forum is enormous - much more than you will ever receive from any apparatus "expert" (of which I like to sometimes think I am - but not often!)
The people on here can save you, if you are wise enough to listen to what they say, and make them qualify their statements, years of research and thousands of $$$
Stay Safe - and good luck on your purchase of a "wet" rescue!
And yes, I agree with MANY of those who post - a "mini" pumper is good for "mini" incidents. DEFINE YOUR MISSION!