The present invention relates to a diaphragm pump device (2) for delivering a fluid, in particular a medical fluid for blood treatment. The present invention also relates to a diaphragm pump having a diaphragm pump device (2) and an actuating device (1) for the diaphragm pump device (2). The diaphragm pump device (2) has a pump chamber body (253) formed with a recess closed by a resilient diaphragm (201) to form a pump chamber (252). Furthermore, the diaphragm pump device (2) comprises an inlet passage (219) connecting the suction opening (215) of the pump chamber (252) and the input connection (204) and a discharge opening (216) of the pump chamber (252). ) With the output connection (205) and an outflow passage (223). A suction valve (202) is provided in the inflow passage (219) and a discharge valve (203) is provided in the outflow passage (223). The discharge valve (203) is a diaphragm valve having a valve body (254A) having a recess formed therein, and the recess has an elastic diaphragm (so as to form a valve space (218) in which the valve seat (225) is disposed. 201) and has a front side facing the diaphragm, and in the open position of the discharge valve it is arranged slightly away from the valve seat, where the valve seat is penetrated by the valve flow path (240). The outlet passage (223) connects the outlet valve passage (240) with the first outlet passage (214) connecting the outlet opening (216) of the pump chamber (252) with the outlet valve space (218). A second outflow channel (214A) connected to the section (205), wherein the cross-sectional area of the discharge valve channel (240) is the area of the valve space (218) surrounding the discharge valve seat (225). Smaller than the cross-sectional area of.本発明は、流体、特に血液処理のための医療流体を搬送するためのダイアフラムポンプデバイス（２）に関する。本発明はまた、ダイアフラムポンプデバイス（２）およびダイアフラムポンプデバイス（２）のための作動デバイス（１）を有するダイアフラムポンプにも関する。ダイアフラムポンプデバイス（２）は、ポンプチャンバ（２５２）を形成するように弾性ダイアフラム（２０１）によって閉鎖された凹部が形成されるポンプチャンバ本体（２５３）を有する。さらに、ダイアフラムポンプデバイス（２）は、ポンプチャンバ（２５２）の吸込
