Multifunction valve (sirio 0175.00)

MULTIFUNCTION VALVE (SIRIO 0175.00)

This valve performs the following functions:

• prevents fuel flowing out when tank is over-filled or in case the vehicle overturns in an accident;
• vents fuel vapours from tank to the active carbon trap filter;
• ventilates the tank if a vacuum builds up inside.

This valve consists of: a float (2); a heavy ball (3); a plate (4), pushed against valve case of spring (5) and plate (8), pushed against plate (4) of spring (9). Multifunctional valve operation may be summarised as follows and depends on fuel tank level:

1. if the tank is full float (2) blocks hole (1) to prevent liquid fuel from reaching active carbon filter and hence damage to the filter;
2. the tank fuel level drops, float (2) is lowered and rests upon ball (3) to open hole (1). When the pressure exercised by fuel vapours on plate (4) overcomes load of spring (5), a ring opening between plate and valve case opens to allow fuel vapours to emerge from the duct (6) and reach the active carbon filter.

1. if the drop in tank fuel level is sufficient to set up a vacuum, this acts on plate (8) and overcomes load of spring (9) so that this moves down to allow tank ventilation through hole (7).
2. if the vehicle overturns, however full the tank, the weight of ball (3) acts on float (2) to push the float against hole (1) and prevent a dangerous flow of fuel to the intake manifold with the attendant risk of the vehicle catching fire.