Abstract: A small-diameter ultrasonic flow meter having opposing transducers comprises a circuit box (4), an outer pipe layer (1), an inner pipe layer (2), and a transducer assembly (3). The circuit box (4) is provided at the outer pipe layer (1). The inner pipe layer (2) is formed integrally by injection molding. Transducer installation bases (23) are formed at ends of the inner pipe layer (2). Transducer assemblies (3) are installed at the installation bases (23). The transducer assemblies (3) are arranged in pairs. The inner pipe layer (2) is installed inside the outer pipe layer (1). The transducer assemblies (3) are arranged opposite to each other to perform transmission and reception operations, thereby reducing energy loss. A standard pipe can be used as the outer pipe layer (1), thereby reducing costs. The inner pipe layer (2) can be assembled quickly and conveniently, provides accurate positioning, and has good sealing performance.

Abstract: A multi-channel ultrasonic flowmeter includes transducer assemblies (21, 22,23, 24) and a pipe housing (10). Four transducer assembly installation holes (9) arranged at two ends of the pipe housing (10) close to flanges (4). The transducer assemblies (21, 22, 23, 24) are provided in the installation holes (9). The transducer assemblies (21, 22, 23, 24) includes transducers (7) and stationary posts (1). An upper portion of the stationary post (1) has a first cylindrical body (109). A lower portion of the stationary post (1) has a flat key-shaped protrusion (105) extending in an axial direction. The flat key-shaped position-limiting protrusion (105) limits rotation of the stationary post (1) around an axial thereof, and ensures accurate positioning of the axis of the stationary post (1). The transducer (7) and the stationary post (1) are respectively sealed to prevent leakage of a fluid.