Radar level meter belongs to the general-purpose radar level meter, it is based on the principle of time travel measurement instrument, radar wave running at the speed of light, the running time can be converted into level signals through the electronic components.The probe sends out high-frequency pulses that propagate at the speed of light in space, and when the pulses meet the surface of the material, they are reflected back and received by the receiver in the instrument, and the distance signal is converted into a level signal.
Synopsis
Radar level meters emit very short microwave pulses of very low energy that are transmitted and received through an antenna system.The radar waves travel at the speed of light.The running time can be converted into a level signal by means of electronic components.A special time extension method ensures stable and precise measurements in very short time.
Radar Level Meter Even if there are false echoes under complex working conditions, the level echoes can be accurately analyzed with the latest microprocessor technology and debugging software.
Importation
The antenna receives the reflected microwave pulses and transmits them to the electronics, where a microprocessor processes this signal and recognizes the echo generated by the micropulse on the material surface.The correct recognition of the echo signal is done by intelligent software with an accuracy of millimeters.The distance D from the surface of the material is proportional to the time travel of the pulse T:
D=C×T/2
where C is the speed of light
Since the distance E from the empty tank is known, the level L is:
L=E-D
Exports
Set by entering the empty tank height E (= zero point), the full tank height F (= full scale) and some application parameters, which will automatically adapt the instrument to the measuring environment.Corresponds to 4-20mA output.
Application Medium
Intelligent radar level meter is suitable for non-contact continuous measurement of the level of liquids, slurries and granular materials, and is suitable for the occasions where there are large changes in temperature and pressure; the presence of inert gases and volatilization.
It adopts the measurement method of microwave pulse and can work normally in the range of industrial frequency band.The beam energy is low and can be installed in all kinds of metal and non-metal containers or pipes, which is harmless to human body and environment.
Measurement Methods
The radar level meter is based on the time-domain reflection principle (TDR), where part of the radar level meter pulse is reflected to form an echo and returned along the same path, but in view of the effects of corrosion and adhesion, the final value of the measuring range should be at least 100 mm from the tip of the antenna. for overflow protection, a radar level meter safety distance can be defined that is appended to the blind zone.The minimum measuring range is related to the antenna.Depending on the concentration, the foam can both absorb and reflect the microwaves, but under certain conditions it is possible to make measurements.Back to the pulse transmitter.
Measuring principle
Radar level meter is based on the principle of time-domain reflection (TDR) as the basis of the radar level meter, radar level meter electromagnetic pulse at the speed of light along the cable or probe propagation, when encountered on the surface of the medium being measured, the radar level meter part of the pulse is reflected to form an echo and return to the pulse along the same path to the transmitting device, the transmitting device and the surface of the medium being measured and the distance between the pulse propagation time is proportional to the calculatedLiquid level height.
Installation Instructions
(1) Wall to the outer wall of the installed short pipe: the minimum distance from the tank wall is 200mm at 1/6 of the tank diameter.
(2) It can not be installed above the inlet.
(3) Cannot be installed in the center position, if installed in the center, multiple false echoes will be generated, and the interference echoes will lead to signal loss.Radar level meter (guided wave)
(4) The diameter of the receiver should be less than or equal to the length of the shielding tube (100mm or 250mm).
Matters needing attention
1. The measurement range is calculated from the point where the beam touches the low level of the tank, but in special cases, if the bottom of the tank is concave or conical, the measurement cannot be carried out when the level is lower than this point.
2. If the medium is low dielectric constant when it is at a low level, the bottom of the tank is visible, at this time to ensure the accuracy of the measurement, it is recommended that the zero point is set at a low height of C position.
3. Theoretically it is possible to measure up to the tip of the antenna, but considering the influence of corrosion and adhesion, the final value of the measuring range should be at least 100mm away from the tip of the antenna.
4. For overflow protection, a safety distance can be defined to be attached to the blind zone.
5. The minimum measuring range is related to the antenna.
Advantages and Applications
1. radar level meter can measure liquid, solid media such as: crude oil, slurry, raw coal, pulverized coal, volatile liquids, etc.;
2. can be measured in a vacuum can be measured in all media constant > 1.2 of the media, the measurement range of up to 70m;
3. power supply and output signals through a two-core cable (circuit circuit), the use of 4...20mA output or digital signal
4. Non-contact measurement is easy to install using extremely stable materials, strong and durable, accurate and reliable resolution of up to 1mm;
5. Not affected by noise, steam, dust, vacuum and other working conditions;
6. Not subject to changes in media density and temperature, the process pressure of up to 400bar, the media temperature of up to -200 ° C to 800 ° C;
7. There are a variety of mounting options: top mounting, side mounting, bypass pipe mounting, conduit mounting, and the installation of a variety of options: top mounting, side mounting, bypass pipe mounting, bypass pipe mounting, bypass pipe mounting, and conduit mounting.Installation, bypass pipe installation, wave guide pipe installation;
8. debugging can be a variety of ways to choose from: using the programming module debugging (equivalent to an analytical instrument), SOFT software debugging, HART handheld programmer debugging, debugging is convenient and fast!
Selection Points
The correct selection of radar level meter can ensure the better use of radar level meter.What kind of radar level meter should be selected should be decided according to the physical and chemical properties of the measured fluid medium?So that the radar level meter diameter, flow range, lining materials, electrode materials and output current, etc.?Can be adapted to the nature of the measured fluid and flow measurement requirements.
1, precision function check
Accuracy level and function according to the measurement requirements and the use of occasions to choose the instrument accuracy level, to achieve cost-effective.For example, for trade settlement, product delivery and energy measurement occasions, should choose a higher level of accuracy, such as 1.0 level, 0.5 level, or higher; for process control occasions, according to the control requirements to choose a different level of accuracy; some of them are just detecting the flow of the process, without the need to do precise control and measurement of the occasions, you can choose a slightly lower level of accuracy, such as 1.5, 2.5, or even 4.0, then you can use inexpensive insertion radar level meter.4.0 level, then you can choose the inexpensive insertion radar level meter.
2, the measurable medium
Measuring medium flow rate, instrument range and caliber Measurement of general media, radar level meter full-scale flow rate can be in the measuring medium flow rate of 0.5-12m / s range of options, the range is relatively wide.Selection of instrument specifications (caliber) is not necessarily the same as the process pipeline, depending on the measurement of the flow rate range in the flow rate range to determine, that is, when the pipeline flow rate is low, can not meet the requirements of the flow meter, or in this flow rate measurement accuracy can not be guaranteed, the need to reduce the caliber of the instrument, so as to improve the flow rate of the pipeline, to get a satisfactory measurement results.
Radar level meter maintenance
Radar level meter mainly consists of electronic components and antenna, there is no moving parts, in the use of very few failures in the use of the occasional problem encountered in the use of some volatile organic tank will be in the radar level meter horn or antenna will be crystallized, as long as they are regularly checked and cleaned can be, the amount of maintenance is small.
In routine maintenance, you can use a PC to remotely observe the reflected wave curve, and for the new interference waves that may be generated later, you can utilize the level meter's function of identifying false waves to remove the influence of these interfering reflected waves, so as to ensure accurate measurement.
