present invention, the first system (24) comprising a valve for controlling the flow of medium in the second to the system (26), the reservoir (25) is formed and the passage opening (9) including, a structure of the deformable dome (3), the valve first connector opening (15) connecting the (1) to the first system (24), the passage opening so as to open and close the passage opening ( 9) and comprising interacting contact elements (23), a valve cover (5), is connected air-tightly to the valve cover (5) to the structure of the deformable dome-shaped as well (3), the valve (1) includes a second connector openings (17) connected to the second system (26), and is connected to the reservoir (25), and a valve base (7), relates to a valve. Structure of deformable dome (3) is in the open state of the valve (1), the structure of the deformable dome (3) is deformed, the flow path opening (9) of contact elements (23) not connected, to allow the medium to flow into the first (15) first system second system from (24) through and the connector opening and the passage opening in the second (17) (9) (26), and in the closed state of the valve (1), the structure of the deformable dome (3) is in its original dome shape, the passage opening (9) is connected to the contact element (23), thus, it is closed configured. The present invention further relates to a pump apparatus comprising the above-mentioned valve (1) and (47) and the milking device (41)本発明は、第1のシステム(24)から第2のシステム(26)への媒体の流れを制御する弁であって、貯槽(25)を形成し且つ流路開口(9)を含む、変形可能なドーム形状の構造(3)と、弁(1)を第1のシステム(24)に接続する第1のコネクタ開口(15)と、流路開口を開閉するよう流路開口(9)と相互作用する接触要素(23)とを含む、弁カバー(5)と、弁カバー(5)に並びに変形可能なドーム形状の構造(3)に気密に接続され、弁(1)を第2のシステム(26)に接続する第2のコネクタ開口(17)を含み、且つ貯槽(25)に連結される、弁ベース(7)とを含む、弁に関する。変形可能なドーム形状の構造(3)は、弁(1)の開放状態において、前記変形可能なドーム形状の構造(3)が変形させられ、流路開口(9)が接触要素(23)に接続されないで、媒体が第1(15)及び第2(17)のコネクタ開口並びに流路開口(9)を通じて第1のシステム(24)から第2のシステム(26)に流れるのを可能にし、且つ弁(1)の閉塞状態において、変形可能なドーム形状の構造(3)がその本来のドーム形状にあり、流路開口(9)が接触要素(23)に接続され、故に、閉塞されるように構成される。本発明は、更に、上述の弁(1)を含むポンプ装置(47)と
