LD739 Liquid level sensor, adopts advanced signal processing technology and high-speed signal processing chip, breaks through the influence of the container wall thickness, and realizes the real non-contact detection of the liquid level height in the closed container. The liquid level sensor (probe) is installed on the upper and lower part of the outer wall of the tested container (high and low level of the liquid level). The non-metal container does not need to be opened, easy to install, and does not affect the production. It can realize the detection of various liquid level of toxic substances strong acid and various liquid levels in high pressure closed container. The sensor has no special requirements for the material of liquid media and non-metallic containers, and can be widely used.