User:Satyaki das/Excess Vapour Reservoir

EVR is a term coined for use in automobile jargon. EVR stands for “Excess Vapour Reservoir”, coined at TVS Motor Company.

EVR is an additional, extra or supplementary space provided in automobile tanks to hold any vapour generated in the plastic fuel tank (gasoline based vehicles).

Vapour is generated inside the tank due to various reasons such as high ambient temperature of the environment or due to exposure to heat   absorbed due to close proximity to the engine.

Primary purpose of the EVR is to prevent any vapour from occupying the progressively decreasing volume within the tank and exerting pressure on the liquid surface (as per Pascal’s law ), leading to fuel loss through any breather / vent arrangement of the tank.

All modern vehicles are fitted with charcoal canisters or some other measure to prevent vapour loss / minimize gasoline emission through the breather arrangement but these fail to function properly when the vehicles are unused for a long time or exposed to high ambient ( sunlight) for a long period.

The EVR can come in handy in such cases, as tanks with EVR arrangement would be able to hold back larger quantity of fuel vapour inside the EVR, not letting the vapour escape immediately from the tank.

The tank would not hold back the fuel vapour inside the tank indefinitely but if sufficient time is allowed, the vapour would cool down and become liquid again. This would definitely reduce fuel loss as vapour as well as emission of this vapour as pollutant.

The EVR thus functions without affecting the volume of fuel inside the tank. Please note that the final volume of the tank would be calculated exclusive of the volume provided by the EVR arrangement.

Work still in progress on this.