The intelligent external ultrasonic level gauge (hereinafter referred to as the level gauge) adopts advanced signal processing technology and high-speed signal processing chip, which breaks through the influence of container wall thickness and realizes true non-contact measurement of the liquid level in a closed container . The ultrasonic sensor (probe) is installed directly under the outer wall (bottom) of the container to be tested, without opening a hole to the container to be tested, and is easy to install and does not affect production. It can accurately measure the level of various toxic substances, strong acids, strong alkalis and various pure liquids in high-pressure airtight containers. The level gauge has no special requirements for the material of the liquid medium and the container, and adopts an explosion-proof design to meet explosion-proof requirements and can be widely used