FAQ Overfill protection for bottom loading tank vehicles

The control unit EUS-2 serves as a stationary part of the overfill prevention system for tank trucks with bottom loading and vapour recovery, which supply e.g. petrol stations or airport tank farms with fuels, as secondary shut-off system to prevent overfilling of a tank compartment.

The control unit detects when a compatible sensor, which is installed in each tank compartment, is immersed in liquid and immediately switches off the filling release. The control unit also checks the safe electrostatic grounding of the tank truck and the correct connection of the vapour recovery hose.

The EUS-1-STP disconnector socket with parking socket serves in conjunction with the pluggable EUS-1-SSK7 coiled cable as a defined disconnection point if the tank truck driver should forget to disconnect the plug from the socket on the tank truck.

The control unit also detects when the plug is put on the parking socket. With the appropriate configuration, one of the additional control outputs can be used to control a traffic light or a barrier to allow the tank truck to drive away when the plug is back in the parking position. Defective or worn out cables can also be easily replaced through the plug connection.

According to the American API Recommended Practice 1004, a 6-pin socket with 3J bayonet coupling the tank truck should be used for optical 5-wire sensors, whereas a 10-pin socket with 4J bayonet coupling should be used for optical 2-wire and thermistor sensors.

Since control devices according to European standard EN 13922 should automatically identify the type of connected sensors, a 10-pin connector shall be used in the European Union for all types of sensors.

This is not always the case in practice and outside Europe, so that the 7-pin connector plug with 3J locking is often required for tank trucks with optical 5-wire sensors, which are equipped with a 6-pin socket. The additional 7^th pin is used to identify the parking socket.

The standardised control output “Filling release” switches to release if a safe electrostatic grounding and the proper connection of the vapour recovery hose have been detected and no sensor is immersed in liquid.

By comparing the additional configurable control outputs (e.g. in the operating mode “Grounding” or “Overfilling”) with the standardised control output “Filling release”, it can be easily recognized whether the missing release is due to an actual overfilling or poor grounding of the truck.

Furthermore, one of the control outputs can be used to switch traffic lights to “green” or to open a barrier in combination with the parking socket.