fatbillybob

Anyone know what is the driving gas plumbed in fire systems that use AFFF foam? Does it use just compressed air? Nitrogen? Co2? It is not halon.

APKhaos

CO2.

The field refill procedure is to replace the spent CO2 cartridge and the outlet seal, add water and the AFFF agent, close and seal the fire bottle. The bottle is not under pressure until you pull the Fire handle, which pressurizes the bottle with CO2. The pressurized AFFF fluid breaks the weak seal between the bottle and the lines, and the system discharges.

GUMBALL

That is true for the Non-Pressurized bottles. The advantage of a non-pressurized (cartridge system) is that the bottle, or the car (as in F1 and Indycars) can be transported by air.
For the bottles that are pressurized, the gas is nitrogen.

APKhaos

Good point. AFFF comes in both flavors, pressurized bottles and non-pressurized.

Another point: Being water based, they need to come out of the car in freezing conditions. Don't leave you AFFF bottle in the car over a hard winter.

kary993

So I coul duse som education on AFFF systems. There are some that electrically activiated and others that are mechanical? What are the differences? I understand the pressurized versus not trade offs but in general why would one pick a mechanical or electral activiated unit in either pressurized or non-pressurized versions?

Thanks!

jrotsaert

It's all about cost and speed... mechanical systems are cheaper. If your car is burning, would you rather pull a wire vigorously or push a small button as you exit? ditto for the outside button and the marshall's actions. If it's pull, you'll save $200 on the unit and about half as much on the install.
Again, the non-pressurized is nice because it allows refill. I personally opted for electrical pressurized
JM

GUMBALL

It is my understanding that SPA Technique was developing a "freeze proof" variation of AFFF, I don't know if it on the market yet.

As for the different flavors:
-pressurized mechanical is cheaper, less likely to be discharged inadvertantly, simpler to install, and a little more damage proof. This system is most often installed in GT cars.

-pressurized electrical has the option of being wired into the kill switch circuit, can also be heat activated, and offers a larger variety of mounting locations.
Both of the above systems must be serviced/refilled by a technician. Refill time - about 10 minutes.

-non-pressurized (cartridge) system's biggest advantages are transportability and "do it yourself" refill. This system was developed at the request of the F1 teams (pressurized containers can not go air cargo) The refill kit consists of the AFFF concentrate that you mix with water, and the CO2 cartridge - quite simple.

All of the systems are also available with a carbon bottle.