If you leave for a non-Schengen destination, you always fly from Pier B during this period. This also means that you have to go through border control. Border control follows just after security screening. Make sure you have all your travel documents at hand.
Currently, it is not possible to use the automated border control gates. Every passenger who travels from Pier B (non- Schengen destinations) will have to pass through the manned border control.
As in all other locations, you must keep a 1.5-meter distance from others while waiting. While queuing you are required to wear your face mask. Only when it is your turn at the border control you may take off your mask. This way, the police officer can thoroughly check your identity card or passport. As soon as the check has been completed, you will have to put your face mask back on.
General information about the border control is available on https://www.brusselsairport.be/en/passengers/your-travel-planner/border-control