The methods described in the guideline apply in particular for checking Stage II vapour recovery systems during normal operation of the filling station, as the vapour recovery rate can be determined during any filling process. Since petrol flow is required when using these methods, they are less suitable for maintenance and adjustment works because of the large amounts of petrol obtained. The methods are primarily intended for checking Stage II vapour recovery systems by the relevant authorities and experts. Furthermore, wet methods are used as reference methods.