M-ELL-SA External level switch is a non-contact level switch by using the Variable frequency ultrasonic technology, it is widely applied to all kinds of liquid level detection. The measuring probe is installed on the external wall of the container. And it belongs to a completely non-contact instrument which measure the level from outside of tank. Working Principles of the External Level Switch The measuring probe of the instrument can send the ultrasonic and detect the residual vibration signal in the wall of the container. The amplitude of the residual vibration signal will becomes smaller when the liquid is over the probe. A switch signal will be outputted after such change is detected by the instrument. The Variable Frequency Ultrasonic Technology is invented by the DingHua and it is the world¡¯s leading ultrasonic signal change detection technology. The main problem for the traditional ultrasonic level switch is that the ultrasonic signal can be interfered by the attachments from the tank wall and the amplitude of residual vibration signal can be changed by the drift of the temperature and time, thus the misinformation phenomenon is easy to appear. More owned the patent of self adaptive ultrasonic technology of variable amplitude variable frequency and it can effectively eliminate the interference and drift to test the changes of the signal correctly. So that it can be applied to a variety of complex site conditions, stable and reliable long-term work. This product adopts the "micro vibration analysis" external sonar signal processing technology and leading manufacturing process, and ensure the reliability and durability of ELL-SA external variable frequency ultrasonic level switch. Application There is no need to open a hole on the tank wall to install the sensors when the ELL-SA series external level switch is installed. The instrument neither contact the liquid medium nor contact the gaseous medium in the container. Therefore, the installation is simple and quick, safe and secure. No need to clear the tank while repair and maintenance, no influence on the normal operating. ELL-SA series external level switch is applicable to fixed-point liquid level measuring and alarm of all kinds of containers and liquid. It can be widely used in petrochemical, chemical, oil depots, oil, electricity, liquid storage, pharmaceutical and other industries. And it has a significant advantage in the pressure vessel, dangerous chemical liquids, flammable and combustible liquids and fixed-point liquid level measuring and alarm fields. Product features 1¡¢Safety: the valves, communicating pipes, joints are not used in the measurement of poisonous, corrosion, pressure, easy to bums, volatile and leak liquid, and there is no leaks, no contact with the liquid and gas in the container, which is very safe. Even under the condition of instrument damage or repair, there will be no possibility for leakage, poisoning and explosion. (Measuring principle diagram) 2¡¢Easy installation and maintenance: There is no need for tank cleaning and open fire during the installation, no impact on production 3¡¢Durability and reliability: There is no mechanical moving parts in the sensor and instrument, strict sealing, isolation, will not wear or corrode. 4¡¢Widely applicable: It has nothing to do with the medium pressure, temperature, density, dielectric constant, viscosity, and presence of corrosion. carton box and gift box, according to requirement