Metering pump for conveying a mounting medium by change in volume of a pumping chamber

Metering pump for conveying a mounting medium by change in volume of a pumping chamber, wherein the pumping chamber (150) at least by a base unit (110), a wall member (130) and a compression unit (120) is defined, wherein the base unit (110) and the compression unit (120) are rigid and the wall member (130) and an O-ring elastically and to the change in volume of the delivery chamber (150) is reversibly deformable, wherein the pumping chamber (150) with an inlet valve (111) and an outlet valve (112) is connected, wherein the inlet valve (111) closes and the outlet valve (112) opens when the pumping chamber (150) is compressed, and the inlet valve (111 ) opens and the outlet valve (112) closes when the pumping chamber is expanded 150th