Absorption is the process where one substance is drawn into another. In vehicles, this happens in several systems to control emissions and noise. The evaporative emissions system uses a charcoal canister to capture fuel vapors. This canister absorbs raw fuel gas escaping from the tank, preventing it from venting into the atmosphere.
Acoustic absorption is also key to driver comfort. Sound deadening pads are placed inside doors and firewalls. These pads use open-cell foam or felt to soak up engine hums and road noise, turning sound waves into low heat.
In engines, oil absorption is a sign of wear. Rubber seals and hoses can absorb oil, causing them to swell, soften, and leak. Choosing the right rubber compounds prevents this swelling, keeping hoses intact under high engine temperatures.