FDT-25W is a wall mount ultrasonic flow meter. It is designed to measure the fluid velocity of liquid within a closed conduit. This transducer is a noncontacting, clamp-on type, which will provide benefits of non-fouling operation and easy installation. The FDT-25W transit-time flow meter utilizes two transducers that function as both ultrasonic transmitters and receivers. This transducer is clamped on the outside of a closed pipe at a specific distance from each other. It can be mounted in W-method where the sound transverses the pipe four times. This selection of the mounting method depends on pipe and liquid characteristics. The flow meter operates by alternately transmitting and receiving a frequency modulated burst of sound energy between the two transducers and measuring the transit time that it takes for sound to travel between the two transducer. Applications include running water, HAVC, water conservation, metallurgy, chemical industry, machinery, energy.