PROBLEM TO BE SOLVED: To provide a pressure detector capable of inhibiting the increase of the volume of a gas phase section as well as ensuring that a required measurement range can be maintained.SOLUTION: The pressure detector comprises: a case C connectable to a liquid flow passage； and a diaphragm member M which is mounted within the case C, partitions a liquid phase section S1 into which a liquid for the flow passage can be filled and a gas phase section S2 into which a gas can be filled, and is displaceable according to the pressure of the liquid filled in the liquid phase section S1； the pressure detector detecting the pressure of the gas phase section S2 to detect the pressure of the liquid in the flow passage. In the gas phase section S2, an opening Cb1 is formed that allows the gas to flow in or out according to the displacement of a diaphragm membrane M, and a flow passage R is also formed that allows the opening Cb1 to retain inflow or outflow of the gas in the course of the diaphragm member M displacing to the gas phase section S2.SELECTED DRAWING: Figure 9COPYRIGHT: (C)2020,JPO&INPIT【課題】気相部の容量が増大してしまうのを抑制しつつ必要な測定レンジを確保することができる圧力検出器を提供する。【解決手段】液体の流路に接続可能なケースＣと、ケースＣ内に取り付けられ、流路の液体を充填し得る液相部Ｓ１と、気体を充填し得る気相部Ｓ２とを区画するとともに、液相部Ｓ１に充填された液体の圧力に応じて変位可能な膜部材Ｍとを具備し、気相部Ｓ２の圧力を検出することにより流路における液体の圧力を検出する圧力検出器において、気相部Ｓ２は、膜部材Ｍの変位に応じて気体を流入又は流出させ得る開口Ｃｂ１が形成されるとともに、膜部材Ｍが気相部Ｓ２側に変位する過程で開口Ｃｂ１による気体の流入又は流出を保持し得る流通路Ｒが形成されたものである。【選択図】図９
