Reducing petrol vapour emissions

09 July 2009

A European Council Directive on air quality requires that all member states adhere to a Limitation of Emissions. For petrol stations, this means that every petrol dispenser must now be equipped with a vapour recovery system and a vapour recovery monitoring system to reduce harmful emissions. Danfoss solenoid valves and pressure transmitters are helping vapour recovery systems lead the way to cleaner air.

Reducing petrol vapour emissions

Because petrol is a mixture of volatile organic compounds that evaporate quickly into the atmosphere, it contributes to ground-level ozone pollution and smog. And every time you stop to fill your car with petrol, these gases are released from the petrol dispenser. But now, with the latest advances in petrol vapour recovery technology, the amount of harmful gases that evaporate into the air during refuelling is set to fall dramatically. Danfoss is supplying the valves for active vapour recovery systems.

To prevent hazardous gases such as aromatic hydrocarbons (tuluol and xylol) escaping from petrol tanks, the vapour recovery system returns gas vapours, which were previously released into the atmosphere, back into the ground tank. An automatic control guarantees there is no pressure build-up and constantly maintains the ratio of volume of recovered petrol vapour to refuelled petrol at 1:1. The vapour flow is controlled using either a proportional valve, which is controlled hydraulically or electronically, or a speed control.

Danfoss’ electronically controlled proportional valve, based on the EV226A 4.5B G14T proportional valve and the EV210A direct-operated valve, is the product of our collaboration with a petrol dispenser producer and their electronic supplier. The vapour recovery valve operates at a constant differential pressure and uses a Pulse Width Modulation of 300Hz to reduce coil hysteresis. By electronically controlling how much petrol goes into a car, the valve can easily regulate the petrol vapours.

Danfoss pressure transmitters, temperature sensors, petrol vapour recovery valves, contactors and circuit breakers can also be used in petrol, LPG and CNG dispensers. Contact your nearest Danfoss office for further information.