Here is the instruction manual for that filter:
The manual gives the following procedure:
1. Turn off the engine. In switchable filters it is sufficient if you switch to the other filter.
2. Close, if available, the shut off valve before the filter.
3. Open the bleed screw on the filter lid.
4. Open the drain valve. Water and dirt are flushed out of the bowl. Leave the drain valve open as long until cleaned fuel leaks. Collect liquids in a container and dispose according to the local regulations.
5. Close the drain valve and the bleed screw (observe the tightening torque, s. chap. 9.1).
6. Loosen the screws on top of the filterlid in multiple turns and crosswise. Otherwise damage may be caused to the lid.
7. Take off the lid. Remove the springcassette. Lift the filter element at the bracket located at the element out of the filter. Dispose the filter element according to the requirements in chapture 12.
8. Insert the new filter element. It is important to make sure that the sealing surface is the bottom and the “Separ” logo represents the front.
9. Insert the spring cassette.
10. Replace if necessary the lid seal and hold the sealing surface of the filter housing and the lid seal clean. If a new gasket is not on hand, make sure that the seal is free from particles and slightly greased to ensure a perfect seal.
11. Put the lid back to its previous position and tighten the cover screws crosswise (observe the tightening torque, s. chap. 9.1) to prevent damage and leaks.
12. After the system has been primed, the engine can be restarted (s. chap. 8).