The filling sensor is a safety mechanism to prevent overfilling of storage and bunker tanks when they are being filled with petrol, diesel and fuel oil from tank trucks. It consists of a level sensor in the tank and an amplifier with valve in the tank truck.

The QSS/ASS plugs are part of a safety system which prevents the blending of products owing to a faulty connection and which checks the hose connection to the tank truck during the filling process.