● High frequency radar level transmitter
Principle: Transmit-reflect-receive is the basic working principle of high frequency radar level transmitter.
The antenna of the radar sensor emits electromagnetic wave signals in the form of beams, and the emitted waves are reflected on the surface of the measured material, and the reflected echo signals are still received by the antenna.
Every point in the transmitted and reflected beams is collected by ultrasonic sampling. After processing by the intelligent processor, the distance between the medium and the probe is obtained and sent to the terminal display for display, alarm and operation.
Characteristics: The characteristic of high frequency radar level transmitter is that the effect is remarkable under severe conditions. It can be used to measure whether it is a toxic medium, corrosive medium, solid, liquid, dust or mud. In terms of measurement, it has the following characteristics:
1. Continuous and accurate measurement
The probe of high frequency radar level transmitter has no contact with the surface of the medium, which is a non-contact measurement, which can accurately and quickly measure different mediums. The probe is almost unaffected by temperature, pressure and gas (the effect is only 0.018% at 500°C and 0.8% at 50bar).
2. It has the function of suppressing interference echo
3. Accurate, safe, energy-saving
The chemical and mechanical properties of the materials used in the high frequency radar level transmitter are quite stable, and the materials can be recycled, which has an environmentally friendly effect.
4. No maintenance required, high reliability
The microwave is almost free from interference and has no direct contact with the measuring medium, so it can be used in almost various occasions, such as vacuum measurement, liquid level measurement or material level measurement. Due to the use of advanced materials, it is very durable against extremely complex chemical and physical conditions, and can provide accurate, reliable and long-term stable analog or digital level signals.
5. Convenient maintenance and simple operation
The high frequency radar level transmitter has fault alarm and self-diagnosis functions. According to the error code prompted by the operation display module, the fault can be determined and eliminated in time, which makes maintenance and calibration more convenient and accurate, and ensures the normal operation of the instrument.
6. A wide range of applications, almost all mediums can be measured
From the perspective of the tank shape, the high frequency radar level transmitter can measure the liquid level in spherical tanks, horizontal tanks, cylindrical tanks, and cylindrical cones; in terms of storage tank functions, it can measure the liquid level in storage tanks, buffer tanks, microwave tubes, and bypass tubes. The liquid level; in terms of the measured mediums, liquids, particles and slurries can be measured.
Generally speaking, the high frequency radar level transmitters are widely used. It is non-contact measurement. The material is excellent and the failure rate is low.
● Guided wave radar level transmitter
Principle: Guided wave radar level transmitter is a measuring instrument based on the principle of time travel. The radar wave runs at the speed of light, and the running time can be converted into a level signal by electronic components. The probe sends out high-frequency pulses that propagate along the cable probe. When the pulse hits the surface of the material, it is reflected and received by the receiver in the instrument, and the distance signal is converted into a level signal.
1. It has a strong ability to inhibit steam and foam, and the measurement is not affected;
2. It is not affected by liquid density, solid material porosity, temperature and dust when feeding;
3. Low maintenance, high performance, high accuracy, high reliability and long life.
● What is the difference between the High frequency radar level transmitter and Guided wave radar level transmitter ?
The contact method is different: the high frequency radar level transmitter is a non-contact type, and the guided wave level transmitter is a contact type. In other words, in the case of high food grade requirements, the pilot type cannot be used.
Different working conditions of the medium: Guided wave radar level transmitter should consider the corrosiveness and adhesion of the medium, and the installation and maintenance of too long guided wave radar is difficult. Under the working condition of low dielectric constant, the measurement principle of high frequency radar and guided wave radar is based on the difference of dielectric constant. Since the waves emitted by ordinary radars are divergent, when the dielectric constant is too low, the signal is too weak and the measurement is unstable, while the guided wave radar waves propagate along the waveguide rod and the signal is relatively stable. In addition, the ordinary guided wave radar also has a bottom detection function, which can be corrected according to the measured value of the bottom echo signal to make the signal more stable and accurate.
There are differences in selection: high frequency radars can be used interchangeably, while guided wave radars are generally not interchangeable, because the length of the guide rod (cable) is fixed according to the original working conditions, so the choice of guided wave radar is more troublesome than high frequency radar.
The measuring ranges are different: high frequency radar is often used on tanks of 30 and 40 meters, even measuring up to 60 meters. Guided wave radar should also consider the force of the probe (cable). This is also due to the force, the measurement distance of guided wave radar is generally not very long. However, under some special working conditions, guided wave radar has obvious advantages, such as mixing in the tank and large fluctuations in the medium. In such conditions, the measured value of the guided wave radar with a fixed bottom is more stable than that of a flexible radar; as well as level measurement in a small tank. Since the installation space is small (or there is a lot of interference inside the tank), the general radar is not applicable, so the advantages of the guided wave radar are revealed.