Abstract: A relative pressure measuring instrument has a reference pressure feed that offers a high measure of safety and is easy to produce.

Abstract: The aim is to specify a relative pressure measuring instrument having a reference pressure feed that offers a high measure of safety and is easy to produce, having a relative pressure measuring cell (1) having a pressure sensitive element (3), on whose process-facing side there is present during operation a pressure (p) to be measured, on whose process-averted side there is present during operation a reference pressure (pR) to which the pressure (p) to be measured is to be referred, a support (5) on which the relative pressure measuring cell (1) is arranged and which is enclosed in a housing (9), a process connection (15), that is connected to a process-facing end of the housing (9), a measuring instrument housing (17) that is arranged at a process-averted end of the housing (9), and a reference pressure feed through which during operation the reference pressure (pR) is led to the process-averted side of the pressure sensitive element (3), and which leads completely out of the relative pressure measuring inst

Abstract: The piezoelectric vortex sensing element (3, 3′, 3″, 3+) of this vortex flow sensor (1) can be assembled from individual components in a simple manner; if its piezoelectric element (34, 34′, 34″, 34*, 34+, 34++) should be faulty, it can be easily replaced. Also, the vortex sensing element can be made largely insensitive to vibrations acting from outside. The vortex flow sensor (1) serves to measure the flow velocity and/or the volumetric flow rate of a fluid flowing through a measuring tube (2). A bluff body (4) generating Kármán vortices is disposed along a diameter of the measuring tube and fixed to the measuring tube at at least one fixing point (41). The vortex sensing element responds to vortex-induced pressure fluctuations and either is installed in a wall (22) of the measuring tube down-stream of the bluff body in a tight manner or extends into a main bore (46) extending through the measuring tube into the bluff body.