Main advantages of pressure transmitter
(1). Reliable work and stable performance.
(2). Dedicated V/I integrated circuit, few peripheral components, simple and easy maintenance, small size, light weight, and extremely convenient installation and debugging.
(3). Aluminum alloy die-casting shell, three-terminal isolation, electrostatic sprayed protective layer, sturdy and durable.
(4). 4-20mA? DC two-wire signal transmission, strong anti-interference ability and long transmission distance.
(5) There are three indicator heads: LED, LCD and pointer, which are very convenient for on-site reading. Can be used to measure viscous, crystalline and corrosive media.
(6). High accuracy and high stability. In addition to the imported original sensor which has been corrected by laser, the comprehensive temperature drift and nonlinearity of the whole machine in the use temperature range are finely compensated.
Principles and applications of several common level gauges
Several common liquid level sensors, the principle and application of liquid level transmitters
Common liquid level sensors, liquid level transmitters mainly include the following
1. Pressure type liquid level gauge:
There are two types of pressure-type level gauges: bottom-mounted type and drop-in type. The liquid is mainly measured by measuring the pressure at the bottom of the liquid: P=h×γ, and γ represents the specific gravity. If it can be installed on the bottom side of the container, the bottom-mounted type is generally used, that is, an ordinary pressure transmitter; if the liquid level of culverts, underground wells, pools, etc. is measured, because the bottom-mounted type cannot be installed, an input type liquid is required. Position transmitter, put the sensor into the bottom of the liquid, and then introduce the atmospheric pressure into the sensor through the air guide cable to compensate for measurement
2. Magnetic flip-type level gauge:
Magnetic flip-type level gauges can be divided into reed tube type and magnetic resistance type, both of which are attracted to the nearest dry reed tube or magnetic resistance through the float ball with magnetic steel in the tube, and then the resistance value corresponding to the pull-in position is determined. Measure the height of the liquid level
3. Ultrasonic level gauge
The measurement is carried out by the time received during the emission and reflection of ultrasonic waves. The disadvantage is that when air bubbles, dust and other substances are encountered, ultrasonic waves will also be reflected back, causing measurement errors.
4. Radar level gauge
It is measured by the time received when the radar electromagnetic wave is emitted and reflected. The radar wave has a strong penetrating power and can penetrate bubbles, so the anti-interference ability is also strong. The disadvantage is that the price is relatively high.
5. Float level gauge
The principle is the same as that of the magnetic flap, except that the floating ball is on the outside of the stainless steel tube, and the reed switch or magnetoresistance is inside the stainless steel tube. This is relatively intuitive, but it is not suitable for media with high viscosity and small particles.
6. Tuning fork level gauge
The tuning fork level gauge uses a pair of piezoelectric crystals installed on the tuning fork base to make the tuning fork vibrate at a certain resonance frequency. When the tuning fork of the tuning fork level gauge contacts the measured medium, the frequency and amplitude of the tuning fork will change. These changes of the tuning fork level gauge are detected and processed by smart circuits and converted into electrical signals
7. Radio frequency admittance level gauge
Radio frequency admittance is a kind of liquid level measurement technology developed from capacitive type. It is a new type of measurement technology that is more reliable, more accurate and more adaptable than capacitive type. Admittance is impedance in electricity. Inversely, it is a combination of resistance, capacitance, and inductance. The radio frequency admittance level gauge adds an oscillator buffer circuit and an AC conversion chopper drive circuit on the basis of the circuit of the capacitive level gauge, through a unique circuit With the sensor structure, the admittance change perfectly realizes the conversion of electrical signals. Maintenance-free, strong anti-interference ability, can overcome the influence of steam, foam and stirring on the measurement
8. Magnetostrictive level gauge
When the sensor of the magnetostrictive level gauge is working, the circuit part of the sensor will excite a pulse current on the waveguide wire, and when the current propagates along the waveguide wire, a pulse current magnetic field will be generated around the waveguide wire. There is a float outside the sensor rod of the magnetostrictive liquid level gauge, which can move up and down along the rod with the change of liquid level. There is a set of permanent magnetic rings inside the float. When the pulse current magnetic field meets the magnetic ring magnetic field generated by the float, the magnetic field around the float changes so that the waveguide wire made of magnetostrictive material generates a torsional wave pulse at the position of the float. This pulse moves along at a fixed speed. The waveguide wire is passed back and detected by the inspection agency. By measuring the time difference between the pulse current and the torsion wave, the position of the float can be accurately determined, that is, the position in the liquid surface. The technical advantages of the magnetostrictive level gauge: The magnetostrictive level gauge is suitable for measuring the level of various media with high precision requirements, and its maximum allowable error is only 1mm. The magnetostrictive level gauge can also be applied to two different types. Measurement of the interface between liquids.
Other liquid level gauges include: externally attached liquid level switches, float level switches, etc.