How do i adjust closing speed of briton 2130 door closer?

To adjust the closing speed of a Briton 2130 door closer, locate the speed adjustment valves on the closer body. Typically, there are two valves: one for the closing speed and another for the latching speed. Use a flathead screwdriver to turn the closing speed valve clockwise to slow down the closing speed or counterclockwise to speed it up. Make small adjustments and test the door's operation after each change to achieve the desired closing speed.