Currently we have several types of ultrasonic sensors, which allow direct installation into the pipe or they can come pre-installed in a measuring tube. Suhgrupos distinguish two sensors such as used with the Doppler method or the method of transit time of the signal:

■ Sensors external fixation, such as "clamp-on"

■ Insertion Sensors

Sensors external fixation, such as "clamp-on"

Sound waves can pass through matter without causing harmful effects. Thanks to this property, the sound waves are very useful for applications in medical diagnostics in endurance of materials and flow measurement. In regard to flow measurement, this feature allows the sensor can be located on the outside of the pipe and not have to necessarily be in contact with the fluid. We normally refer to the devices mounted in this way as sensors external fixation (Fig. below). A feature of the sensors of external fixation is that ultrasound waves always travel throughout the central diameter of the pipe because the pipe wall allows the passage of ultrasound waves.

Figure: External fixation sensors are mounted directly on the outside of the pipe. A special mounting rail facilitates accurate positioning.

Insertion sensors

The sensors are in direct contact with the fluid are known as "sensor insertion or immersion." Insertion sensors are used when the pipe is made of granular materials such as concrete, which do not let the sound waves. Flowmeters are also used in system with transit time signal ticamino multilateral, ie they measure different acoustic paths of the plane passing through the pipe. An example is the dual acoustic path systems. Multipath systems offer better linear behavior and are less susceptible to disruption in the flow velocity profile.

Ill.: The insertion sensors are immersed in the fluid. The installation of the sensor bracket is welded to the pipe wall. Photo: Insert Sensors "How Prosonic" E + H.

Measuring tube / sensor online:

Ultrasonic sensors can be attached directly to the pipe (external fixation sensors) or can be welded to the pipe wall (sensor insertion). Thus, the prefabricated measuring tubes are not essential for ultrasonic flowmeters. A measuring tube basically acts as a support for the sensors.

Ill.: prefabricated measuring tube insertion four sensors and two acoustic paths measured. Photo: Flow Online "Prosonic Flow" E + H.

Prefabricated measuring tubes (see Figure above) are ideal for transferring measurement accuracies determined in the laboratory directly to the place of execution. A line sensor consists of a prefabricated measuring tube insertion sensors complete with pre-installed. The configurations of these online sensors typically use a multipath system consisting of two, three or five pairs of sensors.