The liquid level detection of LPG spherical tank in petrochemical enterprises is quite complicated. Generally, radar liquid level gauge or optical fiber liquid level gauge are used, but holes must be made in the spherical tank. As a pressure vessel, the more holes are made in the vessel, the lower safety factor of pressure vessel. The installation of the external ultrasonic liquid level meter can not stop production, clear the tank or fire. It can be said that it is an ideal choice for industrial liquid level measurement.

The external ultrasonic liquid level meter adopts the principle of sonar echo ranging and uses the ultrasonic equipment installed outside the tank and pipeline to measure the liquid state of the equipment. The ultrasonic signal is continuously transmitted through the outer wall of the equipment into the measured liquid, and then the echo signal is detected by the sensor element. The reflected echo transmitted and received is related to the height and density change of the measured liquid, and the measurement results are calculated by the electronic circuit. The calculated measured value can be the switch value output, analog value or digital value.

In the application of the external ultrasonic liquid level meter, it is required that the measured liquid shall not be filled with dense bubbles or suspended with a large number of solids, such as crystals, and the bottom of the tank shall not sink with a large number of precipitates; the tank body can be made of the same material (such as plastic, glass, stainless steel, carbon steel, etc.).

The external ultrasonic liquid level meter is a transmitting unit that transmits ultrasonic wave through the wall of the container. The speed of ultrasonic signal transmitted in the liquid at the speed of sound is between the filtered signal reflected through the inner wall of the container and the signal reflected back through the liquid surface. The time difference of the reflection signal received by the ultrasonic sensor is proportional to the height of the liquid surface. Any other multiple reflections in the calculation are compensated.

The external ultrasonic liquid level meter measures the continuous liquid level. The ultrasonic sensor is installed at the bottom of the tank or container. The ultrasonic indicates the liquid level through the time difference of the liquid, and is converted into the analog output signal. It can also provide the on-off output signal of the high and low liquid level alarm.

The installation of the external ultrasonic liquid level meter does not need hot work and opening. It belongs to the external measurement. The installation is magnet adsorption. The installation and maintenance are very convenient. It is widely used in the measurement and control of the liquid level of the spherical tank and horizontal tank in the petrochemical industry.

The external ultrasonic liquid level meter designed by SMAGALL adopts a unique algorithm and technology, which overcomes the influence of liquid fluctuation caused by tank feeding or temperature change on liquid level measurement and ensures the stability of measurement. Convenient for installation personnel to operate, saving time and improving efficiency.