A pressure measuring System (11, 111, 211) is described comprising a sensor assembly (13, 113, 213) and a vessel adapter (17, 217), with the sensor assembly defining a compartment (19, 119, 219, 220), comprising a measurement port (29, 129, 229, 230), an actuator (21, 121, 221, 222) for enabling and disabling pressure transmission across the measurement port, and at least one pressure sensor (23, 123, 223, 224, 225) for measuring a pressure in the compartment relative to a reference pressure, and the vessel adapter defining a fluid chamber (47, 247, 248), said chamber being in pressure connection with the compartment by means of said measurement port, and characterized in that in-between the compartment and the fluid chamber at least one membrane (15, 215) is located which separates the medium in the compartment from the medium in the fluid chamber. The pressure measuring System is used to measure the pressure of a medium in a vessel adapter relative to a reference pressure. In a further embodiment the pressure measuring System is adapted to measure the differential pressure of a medium flowing through a vessel adapter with a flow restrictor.
