guided wave radar

Liquid level gauge series>>ZWRD702Guided wave radar liquid level gauge：

1、 Instrument Overview:

guided wave radarThe main technical indicators meet or exceed similar products at home and abroad, and the installation and debugging are simple. It can be used alone or in a network, with advantages such as low maintenance, high performance, high precision, high reliability, and long service life. The transmission of microwave signals is not affected by the atmosphere, so it can meet the requirements of harsh environments such as volatile gases, high temperature, high pressure, steam, vacuum, and high dust during the process. This product is suitable for harsh environments such as high temperature, high pressure, vacuum, steam, high dust, and volatile gases. Continuous measurements can be taken for different material levels.
2、 Measurement principle:
guided wave radarIt is a measuring instrument based on the principle of time travel, which emits extremely short microwave pulses with low energy through an antenna system and receives them. Radar waves travel at the speed of light. The running time can be converted into level signals through electronic components. The probe emits high-frequency pulses and conducts them along the cable or pole probe. When the pulse encounters the surface of the material, it is reflected back and received by the receiver inside the instrument, which converts the distance signal into a level signal. A special time extension method can ensure stability and measurement in a very short period of time. Even if the working conditions are complex and there are false echoes, micro processing technology and debugging software can accurately analyze the echoes of the material level.
1. Input:
The reflected pulse signal is transmitted along the cable or pole probe to the electronic circuit of the instrument, and the microprocessor processes this signal to identify the echo generated by the microwave pulse on the surface of the material. The correct recognition of echo signals is completed by intelligent software, and the distance D from the material surface is proportional to the time travel T of the pulse: D=C × T/2, where C is the speed of light. Since the distance E of the empty tank is known, the material level L is L=E-D;
2. Output:
By inputting the empty tank height E (=zero), full tank height F (=full range), and some application parameters to set, the application parameters will automatically adapt the instrument to the measurement environment. Corresponding to 4... 20mA output;
3. Measurement range:
F - Measurement range; E-empty tank distance; B - Top blind spot; The top blind zone of the H-probe to the tank wall refers to the smallest distance between the highest material surface and the measurement reference point. The bottom blind spot refers to a distance near the bottom of the cable that cannot be measured. The effective measurement distance is between the top blind spot and the bottom blind spot;
4. Attention: Only when the material is located between the top blind spot and the bottom blind spot can reliable measurement of the tank level be ensured.

3、 Data processing:
The radar is set by inputting the empty tank height L (=zero point), full filling height H (=full range), and some application parameters, which will automatically adapt the instrument to the measurement environment. It corresponds to 4-20mA output.

4、 Applicable occasions:
Suitable for harsh environments such as high temperature (350 ℃), high pressure, vacuum, steam, high dust, and volatile gases. Continuous measurements can be taken for different material levels. The main technical indicators of this instrument reach or exceed similar products at home and abroad, and it is easy to install and debug. It can be used as a single unit or in a network, and can be widely used in industries such as metallurgy, building materials, energy, petrochemicals, water conservancy, and grain.
5、 Performance characteristics:
1. Strong universality: capable of measuring liquid and material levels, meeting measurement requirements for different temperatures, pressures, and media. The highest measurement temperature can reach 800 ℃, and the highest pressure can reach 5MPa. It can also be applied to harsh environments such as corrosion and impact.
2. Anti hanging material: The circuit design and sensor structure of * ensure that its measurement is not affected by sensor hanging material, and there is no need for regular cleaning to avoid measurement errors.
3. Maintenance free: There are no movable parts during the measurement process, and there is no mechanical component damage issue, so no maintenance is required.
4. Anti interference: contact measurement, strong anti-interference ability, can overcome the influence of steam, foam and agitation on measurement.
5. Accurate and reliable: Diversified measurement quantities make measurements more accurate, measurement is not affected by environmental changes, high stability, and long service life.
6、 Technical indicators:
1. Operating frequency: 100MHz-1.8GHz;
2. Measurement range: Cable type: 0-35m pole type, coaxial type: 0-6m;
3. Repeatability: ± 3mm;
4. Resolution: 1mm;
5. Sampling: Echo sampling 54 times/s;
6. Response speed:>0.2S (depending on specific usage);
7. Accuracy:<0.1%;
8. Output current signal: 4-20mA;
9. Communication interface: HART communication protocol;
10. Process connection: G1-1/2, G3/4 flange: DN50, DN80, DN100, DN150;
11. Process pressure: -1~60bar;
12. Power supply: 24VDC (± 10%) Ripple voltage: 1Vpp;
13. Power consumption: max22.5mA;
14. Environmental conditions: Temperature: -40 ℃ to 250 ℃;
15. Shell protection level: IP68;
16. Explosion proof grade: EXiaIICT6;
17. Two wire wiring: instrument power supply and signal output share one two core cable;
18. Cable entrance: M20 × 1.5 (cable diameter 5-9mm).
7、 Installation instructions:
The following installation instructions apply to pole and cable probes, and the measurement and installation methods of tube probes are independent.
Installation location:
1. The recommended distance from the tank wall is 1/6-1/4 of the tank diameter (at least 300mm for concrete tanks and at least 400mm for concrete tanks);
2. Do not install in the middle of metal cans;
3. Do not install it at the discharge port;
4. When selecting the length of the probe, pay attention to the distance between the bottom of the probe and the bottom of the tank being about 30mm;
5. Pay attention to the temperature of the medium.
Obstacles inside the tank:
1. During installation, pay attention to keeping the probe at least 200mm away from obstacles.
Removal of interference:
1. Interference echo suppression: Software can suppress interference echoes to achieve ideal measurement results;
2. Bypass tubes and waveguide tubes (only applicable to liquids) can be used for viscosity not exceeding 500cst to avoid interference.
Liquid standard installation:
For media with viscosity ≤ 500cst and low adhesion, a tubular probe is an ideal solution, with the following characteristics:
Reliability;
1. Can be used for any medium with a dielectric constant greater than or equal to 1.4, measurement is independent of the conductivity of the medium;
2. Obstacles inside the tank and the size of the short tube do not affect the measurement;
3. Higher lateral pressure than the rod probe can withstand;
4. For high viscosity media, it is recommended to use a rod probe.
Installation on horizontal and vertical tanks:
1. The maximum length of the tube probe and rod probe can reach 6 meters. For tanks with a measurement distance exceeding 6 meters, an 8mm cable probe can be selected;
2. The installation and fixing method is the same as the measurement of solid powder silo;
3. There is no limit to the distance from the tank wall, as long as the probe does not come into contact with the tank wall;
4. If there are many obstacles in the tank or it is too close to the probe, please use a tubular probe.
Measurement of corrosive media:
1. If measuring corrosive media, a rod probe with a plastic sleeve can be used for measurement.
8、 Precautions for measurement conditions:
1. The measurement range starts from the point where the beam touches the lower part of the tank, but in special cases, if the tank is concave or conical, measurement cannot be carried out when the level is below this point.
2. If the medium has a low dielectric constant and is visible at a low liquid level, it is recommended to set the zero point at a low height of C to ensure measurement accuracy.
3. In theory, it is possible to measure the position of the antenna *, but considering the effects of corrosion and adhesion, the final value of the measurement range should be at least 100mm away from the antenna *.
4. For overflow protection, a safe distance can be defined to be added to the blind spot.
5. The minimum measurement range is related to the antenna.
6. With different concentrations, foam can both absorb microwave and reflect it, but it can be measured under certain conditions.

9、 Daily inspection and maintenance:
1. Daily inspection and maintenance mainly involve checking whether the power supply voltage and output current are normal. After power on, it takes about 30-60 minutes for the instrument to function properly. If the instrument does not output after being put into operation, it should be checked whether the power supply is truly connected and whether the fuse is burnt out.
2. When in use, it is integrated with the equipment, and the entire system's radar level gauge is sealed, so it is also necessary to check the sealing condition of each component connection regularly.
3. The operating temperature inside the radar head is 65 ℃. Under normal usage, the temperature will not exceed this limit, but if the temperature of the measured medium is very high, the temperature inside the radar head may exceed 65 ℃. At this point, a small amount of wind can be used to blow into the radar head from the rainwater cap through this φ 6X1 copper tube, in order to lower the internal temperature. Do not use water or other liquids for mechanical cooling.
4. Volatile organic compounds can crystallize on the horn or antenna of the radar level gauge, and should be inspected and cleaned regularly.
Notes:
1. The measurement range starts from the point where the beam touches the lower part of the tank, but in special cases, if the tank is concave or conical, measurement cannot be carried out when the level is below this point.
2. If the medium has a low dielectric constant and is visible at a low liquid level, it is recommended to set the zero point at a low height of C to ensure measurement accuracy.
3. In theory, it is possible to measure the position of the antenna *, but considering the effects of corrosion and adhesion, the final value of the measurement range should be at least 100mm away from the antenna *.
4. For overflow protection, a safe distance can be defined to be added to the blind spot.
Ten installation requirements:
1. For circular tanks with smaller diameters, the minimum distance between the installation point and the tank wall should not be less than 35cm. Typically, the distance between the level gauge and the tank wall is set to 1/6-1/4 of the tank diameter.
2. The radar level gauge cannot be installed directly above the liquid inlet.
3. The radar level gauge cannot be installed in the center of a circular tank to avoid interfering with the signal.
4. During installation, the markings on the flange should point towards the tank wall, and the flange's deviation from the horizontal plane should be less than plus or minus 0.5 degrees.
5. When installing the horn antenna, the lower end of the antenna must be below 20mm from the top of the tank to ensure that the horn antenna is perpendicular to the liquid level and avoid echoes. The horn shaped antenna must extend below the connecting tube.
6. The installation position of the waveguide should be away from the discharge port, and the axis should be perpendicular to the liquid level.
EleventhData Comparison Table:

12、 Selection List:

ThirteenData required for selection:
1. What is the measurement range and what is the required blind spot.
2. The type of medium being measured (liquid or solid, specific names such as water, sewage, mud, gasoline, diesel, toluene, sulfur dioxide, ore, coal, cement, soybeans, wheat, corn, flour, etc.). If it is liquid: whether there is steam, fog, foam, wave, agitation and floating objects on the liquid surface; If it is a solid: whether there is dust, and whether the medium is in particle or powder form.
3. The lowest temperature of the medium, the lowest pressure.
4. The corrosiveness of the medium, if placed in a can, requires knowledge of the material of the can and whether there is a corrosion-resistant lining.
5. Do you need anti-corrosion and explosion-proof, split or integrated.
6. Work environment: open pool, covered pool, horizontal tank, vertical tank, spherical tank, whether the tank is connected to atmospheric pressure, etc.
7. Working power supply: DC 24VDC or AC 220VAC.
8. Output signal: 4-20mA current, or 485 communication output, do I need relay output?
After-sales service
1. The instrument series products sold by Zhongwei ensure the sale of products and spare parts at the same price within two years, and provide corresponding free of charge according to the requirements of the demand.
2. If there are any quality problems with the products provided by our company within one year (excluding vulnerable parts or accessories), we will be responsible for free repairs and provide free skill training for the employees of the demand side.
3. Due to quality issues with the products provided by our company, after verification by our technical department, we will dispatch professional technicians to the site to handle the problem until customer satisfaction is achieved.
4. Outside the warranty period, the product will be returned to the company for repair or sent to the user for repair.
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