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.

Abstract: This sensor for measuring the flow velocity and/or the flow rate of a fluid provides an optical sensor system which is also suitable for use at temperatures higher than 400° C., does not come into contact with the fluid, and requires less space than conventional optical sensor systems. The sensor comprises a tube (1) through which the fluid flows in a first direction and which has a wall (11) in which a first window (2) and a second window (3) of optical, schlieren-free, high-temperature glass are set fluid-tight and pressure-tight at points lying opposite each other along a first tube diameter. A bluff body (4) is disposed along a second tube diameter and fixed in the tube for generating Kármán vortices, whose frequency f is proportional to the flow velocity u. The second diameter is up-stream of, and perpendicular to, the first.

Abstract: To achieve accuracies of the order of 0.75% of the measured value, a digitized, two-dimensional overall image of a bluff body (7), of the internal surface of a measuring tube (2) in the area of the bluff body, of the two fixing zones (71, 72) of the bluff body, and of contour line (51) of the inlet end (5) of the measuring tube is generated by a high-resolution electronic camera (9) located in front of the measuring tube (2) on the axis (3) of this tube. The overall image is divided into three partial images. The first partial image contains only information about the inlet end (5) and the internal surface (4) of the measuring tube, the second contains only information about the bluff body (7) without the fixing zones (71, 72), and the third contains only information about the fixing zones. From shape information about the fixing zones (71, 72) and ideal information characteristic of the ideal shapes of the fixing zones, cross-correlation information is formed.

Abstract: These substitution kits are provided for field-installed volumetric differential pressure flow sensors (101, 102, 103, 104, 105, 106) comprising bores (111, 121) for sensing the fluid pressure and an orifice plate (13) of standard thickness which is fixed fluid-tight between two pipes (1, 2) conducting a fluid to be measured. A first variant of the kit comprises an annular disk (23) which replaces the plate (13) and whose thickness is equal to that of the plate as well as whose opening has a diameter equal to the inside diameter of the pipes. A single bluff body (2311, 2312, 2313, 2314, 2317, 2318, 2319) is arranged in the lumen of the annular disk. The bore (111) of the pipe (1) is fluid-tightly closed by a device (18) after removal of the pressure sensor of the bore (111). A vortex sensing element (19) is inserted fluid-tightly in the bore (121) of the pipe (2) after removal of the sensor of this bore. Acc.

Abstract: To improve both the absolute measurement accuracy and the linearity of the characteristic function and the short-time repeatability of measurements at varying flow velocities, particularly at low flow rates, this electromagnetic flow probe (10) is designed to be immersed in a fluid flowing in a pipe (12), which is to be measured, the direction of immersion being virtually perpendicular to the direction of fluid flow. The probe is further designed to be passed through a hole in a wall of the pipe fluid-tight and comprises a circular cylindrical housing (11) having a predetermined outside diameter adapted to the bore. The front end (14) of the housing extends into the fluid and is closed fluid-tight by a front plate (14") of insulating material in the form of a calotte, which has a radius approximately equal to 1.2 to 1.5 times the outside diameter of the housing. A coil assembly (15) is disposed in the housing for establishing a magnetic field (16) extending through the front plate (14") into the fluid.

Abstract: To increase in the accuracy of vortex flow sensors measuring the flow velocity and/or the volumetric flow rate of a fluid flowing through a measuring tube, the vortex flow sensor comprises a cylindrical bluff body of circular section mounted in the measuring tube. The bluff body has a surface which is roughened. A single vortex-sensing element is responsive to pressure fluctuations caused by the vortices. The roughness can be realized by shallow depressions being identical in shape and either evenly or unevenly, particularly stochastically, distributed over the surface of the bluff body. The depressions can be only provided in a sector of the surface whose central angle is less than 180.degree..

Abstract: This vortex flow sensor (1) for measuring the flow velocity and/or the volumetric flow rate of a fluid flowing in a measuring tube (2) has an improved measurement accuracy according to the following design: A bluff body (4) is mounted in the measuring tube and designed to generate Karman vortices; a vortex-sensing element (5) is responsive to vortex-induced pressure fluctuations; and a turbulence grid (6) is mounted upstream of the bluff body and has openings with at least partially differing cross sections. The turbulence grid cn be circular and formed by radial members and spaced-apart concentric circular members. The turbulence grid can have a thickness D in the direction of flow and be located at a distance x from the bluff body, said thickness and said distance satisfying the inequality: 20D<x<40D.

Abstract: This device (1) produces a steep-fronted liquid pressure wave which strikes a body (12) to be tested with an adjustable table pressure. The device has a measuring tube (10) within or to which the body (12) is fixed, and which has a pressure-proof observation window (13, 14) and a pressure-relief valve (15). A pressure tube (20) with a compression system (25) which compresses a gas is closed on one side by a first diaphragm (29) which forms part of a chamber (27) that is provided with a valve (25). The chamber is closed by a second diaphragm (19) located opposite the diaphragm (29). In tube (10), a piston (18) is movable on guides (17) up to a braking device. To carry out the method, an amount of liquid which only partially fills the tube (10) is applied to the pistons In the chamber (27), a pressure equal to half the bursting strength of the diaphragms (29, 19) is set. The pressure in the tube (20) is increased until the bursting strength is exceeded.