Abstract: A pressure measuring device (2) includes a vibrating ferromagnetic cylinder (4) and mechanically located within a casing (6). A diaphragm (24) is directly connected to the cylinder and forms a pressure measurement surface. Pressure on the diaphragm (24) results in a force and stresses in the cylinder (4) which change the resonant frequency of the vibrating cylinder.

Abstract: A transducer for measuring a parameter of a fluid, such as density or viscosity, comprises two generally parallel tines extending from a common yoke, forming a tuning fork adapted to be immersed in the fluid. The tines are excited to vibrate resonantly and in anti-phase by one or more piezo-electric exciting elements, which are housed in one or more cavities within the tines or the yoke. The vibrations are sensed by one or more similarly-housed piezo-electric sensing elements. The tines are shaped to enhance their sensitivity to the parameter to be measured: for example they are provided with re-entrant surfaces to enhance density sensitivity, or elongated in the direction in which they vibrate to enhance viscosity sensitivity.