The ultrasonic probe is installed directly below the outer wall (bottom) of the tested container during the measurement of external ultrasonic liquid level gauge. It does not need to open a hole, is easy to install, does not affect the field production, and can realize the accurate measurement of various toxic substances and pure liquids in the high-temperature and high-pressure closed container. The instrument adopts explosion-proof design to meet the explosion-proof requirements. The probe is external and does not need to open a hole for the tested container, so as to truly realize non-contact measurement. It is suitable for accurate measurement of liquid medium level in various closed containers, such as toxic, volatile, flammable, explosive, strong pressure and strong corrosiveness. The gauge has no mechanical movable parts and long service life. No corrosion, no pollution, wide use area. In the design work, a reasonable and optimized selection scheme of external ultrasonic level gauge is made according to the different of each project. From the perspective of production and application, the effect is very good.

In the design of a liquid ammonia spherical tank, the external ultrasonic level gauge is also well used. The liquid ammonia in the storage tank is a colorless, toxic liquid with pungent odor and is corrosive to a certain extent. Since the density of liquid ammonia is greatly affected by the temperature, the differential pressure level gauge is not applicable in the project, and the external ultrasonic level gauge is finally selected for detection.

Common applicable medium of external ultrasonic level gauge include liquid chlorine, liquefied gas, liquid ammonia, ethylene, butadiene, gasoline, diesel oil, benzene, liquid bromine, hydrochloric acid, alkali solution, nitric acid, methanol, vinyl chloride, hydrofluoric acid, ethylene glycol, propane, naphtha, ethylene oxide and dimethyl ether.