The Air-Fuel Separator is a mini surge tank which is installed in the tank vent line, near the fuel tank in installations where liquid fuel can enter the vent lines.
It allows vapors to pass through to the carbon canister, but captures any small amounts of fuel that have entered the vent line.
This fuel then drains back into the tank through a separate return line, thus protecting the canister.

An Air-Fuel Separator can also be used instead of floated tank vent valves mounted on the tank.
Perko A/F Separators mount using the same "floating bracket" system used on Perko/Delphi carbon canisters.
A 0588 series Tank Vent Valve is mounted inside each Perko A/F Separator giving it rollover protection, overpressure relief, and the restriction needed to aid in automatic pump shutoff.
A Heat Shield protected model is available for use in engine compartment installations.
Properly installed, A/F Separators can replace tank vent valves, eliminating the need to provide access to distant parts of the fuel tank.