Types and applications of common level meters

Contact measurement started with the steel strip float level gauge, which used various methods to accurately measure the float distance and evolved into various modern instruments such as servo, magnetostrictive, and other thermoelectric technologies. The steel strip float type: the earliest level gauge is now facing updates and replacements.

The float floats on the surface of the medium due to buoyancy, and reads the liquid level value on the scaled steel belt through the speed change gear. When the liquid level rises or falls and breaks the force balance, the float also rises and falls, driving the steel belt to run. The theoretical accuracy is about 2-3mm. It is a free technical exchange platform for thermal power industries such as power plant boilers, steam turbines, electrical, thermal control, and water treatment! The installation is complicated and the reliability is low. Due to the large number of mechanical parts, it is easy for the steel belt to get stuck and not move.

Magnetostrictive type

The electronic components at the upper end of the probe generate a low-voltage current pulse, starting the timing, and generating a magnetic field that propagates downward along the magnetostrictive wire. The float moves up and down along the measuring rod as the liquid level changes. There is a magnet inside the float, which also generates a magnetic field. When the two magnetic fields meet, the magnetostrictive wire twists to form a torsional stress wave pulse. The pulse speed is known, and the calculated pulse propagation time corresponds to the precise change in the liquid level.

The highest accuracy can reach 1mm. The magnetostrictive liquid level has high accuracy and can measure the oil-water interface. However, due to its contact measurement method and high installation and maintenance requirements, it is not widely used in the market.

Since it is greatly affected by medium density and temperature, its accuracy is often poor. In order to eliminate these influences, many other test instruments are needed. As a result, it is very expensive to build a complete static pressure measurement system.

Servo level gauge

Servo-type Level meter is a new type of level meter that has been successful recently. It is mainly used in the high-precision measurement of light oil products. It forms a strong competition with radar level meter. The basic principle is the same as that of steel belt level meter, but it has accurate force sensor and servo system to form a closed-loop regulation system. By considering the gravity of the steel belt itself, the float height is accurately adjusted to achieve the balance of buoyancy and gravity, and the accurate current liquid level to tank top height is obtained to obtain the liquid level value. Thermoelectric Technology Alliance has high accuracy, which can reach 1mm, meeting the metrological requirements and is used for calm, light and non-corrosive liquids.

Hydrostatic level gauge

The static pressure level gauge is quite special. It uses the proportional relationship between the pressure of a uniform liquid and its height to convert the liquid level height by measuring the pressure at the bottom of the liquid.

P=ρgh (P pressure)