Charcoal Canister Delete?

[Mike Arman]

On 6/11/2012 12:46 PM, speedracer.mark at gmail.com wrote:
> Mike,
> They are separate, and PZEV is common in all states, including here in NY. Generally speaking, you
> no longer find "49 state cars," for a variety of reasons.
> Theoretically, the carbon canister can act also as a spark arrestor, saving on fire hazards. If you
> overfill your fuel system, they can also fill up (really hard to do, but theoretically possible),
> creating a fire hazard or an unmetered source of raw fuel into the engine.
>
> BTW, I bet the firewall on your Cessna 150 has one, albeit unpressurized and open to atmosphere.
>
> Mark Rosenkrantz


Well (and Mark, you're a pilot, so you know this), airplane fuel systems are open to the atmosphere 
- as you climb and air density decreases, the air in the tank (plus presumably the vapors) get 
vented out because if they weren't the pressure in the tank would increase (in comparison to ambient 
air pressure) to the point that the tank would swell and the pressure would over-ride the float 
valve and flood the carb.

On descent, air has to be allowed back into the tank because otherwise it could crush, and the 
decreased pressure of the fuel could result in fuel starvation.

As long as the fuel tanks and carburetor are at the same barometric pressure, they're happy.


Cars don't seem to have this problem because most of them won't go to 15,000 feet MSL, and they 
don't go up and down mountains rapidly.


If the fuel system on a car is totally sealed, how do they compensate for the use of the fuel? What 
takes the space in the tank where the fuel was? Or are car fuel systems just not sealed as tightly, 
and the pressure does equalize albeit more slowly?


Remember, most light airplanes are the very best technology 1940 has to offer . . .


Best Regards,

Mike Arman
90V8Q, other stuff