In the industrial field, to measure the liquid level, there are many other methods and principles besides the hydrostatic level measurement of the submersible level gauge.
- The float level gauge is a method that relies on the principle of buoyancy to measure the liquid level. Usually, the observer can read the height of the liquid level intuitively through the cooperation of the float ball and the scale. Advantages: Quick and intuitive readings; low price; easy installation. Disadvantages: low precision; installation is relatively limited by the shape and structure of the container; not suitable for highly corrosive and dangerous media; unable to achieve remote transmission and adjustment.
- The magnetic flap level gauge relies on the magnetic float installed inside the container to drive the magnetic flap outside the container to turn over to realize signal conversion and liquid level display. Advantages: fast and intuitive reading; low price; remote transmission and adjustment possible. Disadvantages: low precision; complicated installation; range limitation; relatively large installation volume.
- The capacitive liquid level sensor measures the level of the liquid level by using the change of the capacitance value between the two electrode plates of the capacitor. Advantages: Small in size, easy to achieve remote transmission and adjustment; suitable for corrosive and high-pressure media. Disadvantages: The dielectric constant of the medium and the upper part of the liquid surface must be kept constant for accurate measurement; the measurement range is limited by the length of the metal rod; there are high requirements for the material of the container; the measured medium is conductive.
- The radar level gauge converts the position of the liquid/object surface by detecting the microwave (electromagnetic wave with a very short wavelength) emitted by itself and reflected by the liquid surface. Advantages: It can measure the liquid level in the pressure vessel, and the influence of high temperature, high pressure, scaling and condensate can be ignored; the accuracy is high; there is no direct contact with the medium; the corrosion resistance is strong; it can be used in a vacuum environment; it is easy to install. Disadvantages: expensive; affected by vessel geometry and material properties; susceptible to electromagnetic interference.
- The ultrasonic level gauge converts the position of the liquid/object surface by detecting the signal of the ultrasonic wave emitted by itself that is reflected by the liquid surface. Advantages: no direct contact with the medium; strong corrosion resistance; high precision; easy installation. Disadvantages: The price is relatively expensive; the ultrasonic wave is greatly affected by the gas composition of the transmission medium; it is greatly affected by the geometric structure of the container; it is not suitable for the medium with bubbles or suspended matter; it is easily interfered by electromagnetic waves.
- The bubble method is to inflate the medium from the bottom of the container through the air source. Only when the blowing pressure in the air supply system is balanced with the hydrostatic pressure at the bottom of the container will the gas enter the container from the trachea to form bubbles. At this time, measuring the air pressure in the air supply system can convert the static pressure of the measuring point, and then obtain the liquid level value. Advantages: strong corrosion resistance; able to measure high temperature media. Disadvantages: higher maintenance costs and lower accuracy.