Fluid meter and fluid measuring module for a fluid measuring device and assembly

A subassembly consisting of a housing, in which a flow channel for a fluid to be measured is formed, that has a polygonal cross section, as well as one elongate module-receiving opening formed in each of the sides of the flow channel, which forms a passage from an outer surface of the housing to the flow channel, wherein the module-receiving openings are aligned along the flow channel, and at least one fluid-measuring module, at least one analysis module and at least one blind cover without any signal transformers and serving as a reflector for acoustic waves, each being separate from the housing,

• the fluid-measuring module comprising a module housing, which has a base section formed as a waveguide for surface acoustic waves, as well as at least one signal transformer, in the form of an interdigital transducer, connected directly to the base section, which is designed to excite surface acoustic waves in the waveguide and/or to receive surface acoustic waves from the waveguide, wherein the waveguide is designed to be brought into surface contact with a fluid on an outer side facing away from an interior of the module housing, and
• the analysis module being designed to measure at least one of an electrical conductivity, a pH, a concentration of a chemical substance, a clouding of the fluid, a redox potential of the fluid, a temperature, and a pressure,
• wherein the fluid-measuring module, the analysis module and the blind cover can be inserted into the module-receiving openings, any module-receiving openings where neither fluid-measuring modules nor analysis module are arranged being sealed by a blind cover,
• the fluid-measuring module being inserted such that the base section of the fluid-measuring module forms a section of an inner wall of the flow channel, which comes into direct contact with the fluid flowing through it, with a result that surface acoustic waves emitted by the signal transformer can be coupled out of the waveguide and can propagate through the fluid in the flow channel as bulk acoustic waves and/or bulk acoustic waves can be coupled into the waveguide and received by the signal transformer.