Liquid level transmitter is the extension and development of pressure transmitter technology, according to the principle that the pressure generated by different specific gravity liquids at different heights is linearly related, to realize the accurate measurement and transmission of the volume, liquid height and weight of water, oil and paste.
Advantage
Advantages of liquid level transmitter:
1. Simple installation, easy to use, strong interchangeability.
2. Suitable for the measurement of liquid level and interface of liquid medium in container.In addition to on-site indication, it can also be equipped with remote transmitter, alarm switch, and complete detection function.
3. Novel indication, intuitive reading, eye-catching, the direction of the observation indicator can be changed according to the user's needs.
4. The measuring range is large and not limited by the height of the storage tank.
5. The indication mechanism is completely isolated from the measured medium, with good sealing, high reliability and safe use.
6. Simple structure, easy installation, easy maintenance, corrosion-resistant, no need for power supply, explosion-proof.
7. High sensitivity of high quality sensing, fast response speed, accurately reflecting the flow or static liquid level of the subtle changes in the measurement accuracy.
8. With intrinsically safe explosion-proof and isolated explosion-proof capability, it can be applied in various hazardous places.
9. Anti-blockage design can realize the measurement of liquid level of paste medium.
10. 100% equidistant scale, LED, LCD three kinds of indication table head, field reading is very convenient.
11. 4-20mA DC two-wire signal transmission, strong anti-interference ability, transmission distance.
12. Fine and unique zero point, full range, non-linear compensation to ensure the accuracy of the instrument within the range of conditions of use, long-term stability.
13. Pressure sensor directly senses the liquid level pressure, not affected by the medium blistering, deposition.
14. The use of a wide range of measured media, can measure oil, water and paste compatible with 316 stainless steel, with a certain degree of corrosion resistance.
Performances
Structure material: isolation diaphragm: 316 stainless steel corrugated diaphragm
Sensor shell: 1Cr18Ni9Ti stainless steel
Cable: φ8 polyvinyl chloride six-core hollow cable (corrosion-resistant polytetrafluoroethylene cable)
In the relay box: 97 × 84 × 147 epoxy resin spraying
Process connection: input type: right-angle bracket hole spacing 50 × 50mm
Hole diameter φ5mm.
Straight rod type: No thread or thread of your choice.
Threaded:M27×2 M20×1.5 or thread of your choice
Flange:DN25 or user's choice.
Anti-corrosion type: Right angle bracket hole distance 50×50mm
Hole diameter φ5mm.
Working Principle
The working principle of the level transmitter is that when the two pressures of the measured medium are passed into the high and low pressure chambers, they act on both sides of the isolation diaphragm of the δ-element (i.e., the sensitive element), and are transmitted to both sides of the measurement diaphragm through the isolation piece and the filling liquid inside the element.
(Float) level transmitter is by the measurement diaphragm and the electrodes on both sides of the insulating sheet each side of a capacitor. When the two sides of the pressure is not consistent, resulting in the measurement of the diaphragm displacement, the displacement and pressure difference is proportional to the two sides of the capacitance is not equal, through the oscillation and demodulation link, converted into a signal proportional to the pressure.The working principle of pressure transmitter and absolute pressure transmitter is the same as that of differential pressure transmitter, but the difference is that the pressure in the low pressure chamber is atmospheric pressure or vacuum.
The A/D converter converts the current from the demodulator into a digital signal, the value of which is used by the microprocessor to determine the input pressure value.The microprocessor controls the operation of the transmitter.In addition, it performs sensor linearization.Resets measurement ranges.Engineering unit conversions, damping, open-square, sensor fine-tuning and other operations, as well as diagnostics and digital communications.
This microprocessor has 16 bytes of program RAM and has three 16-bit counters, one of which performs the A/D conversion.
The D/A converter takes the corrected digital signal from the microprocessor and fine-tunes the data, which can be modified by the transmitter software.The data is stored in EEPROM and remains intact even in the event of a power failure.
The digital communication line provides the transmitter with an interface to an external device such as a Model 205 Smart Communicator or a control system utilizing the HART protocol.This line detects the digital signal superimposed on the 4-20 mA signal and transmits the required information through the loop.The type of communication is frequency-shifted keyed FSK technology and is based on the BeII202 standard.
Usage
1. It is best to choose a stabilized power supply to supply power separately.The stability of the power supply affects the performance index of the transmitter, and it is better to control its error below one-fifth of the allowable error of the transmitter.For products with special power supply requirements, special power supply must be connected.
2. The signal line of the level transmitter should take the cable with shielding to prevent electromagnetic wave interference.
3. Connect the transmitter according to the correct wiring method, and its power-on time should be fifteen to thirty minutes.
4. If the level transmitter is installed in pools, water towers and other occasions, you can sink its probe in the bottom of the water, away from the location of the water flow rate is too fast.
5. In a submersible pump and other large fluctuations in the use of level transmitter installation is best to use the method of inserting steel pipe, steel pipe to be fixed firmly, every distance on the steel pipe to open a hole in the position of the steel pipe away from the water inlet and outlet.
6. Junction box to be fixed firmly, or install a fixed bracket, to prevent in a dry, shaded place, can not be rained on
7. Protect the ventilation cable, can not be bent or blocked, not to mention damage, excess cable can be coiled up in the neighborhood.
8. Outdoor installation of the level transmitter should also take lightning protection measures.
Product Features
Mainly used with industrial field level measurement and control, urban water supply and sewage treatment petroleum, chemical, power plants, hydrological monitoring, reservoirs, dams, hydropower construction and other fields of liquid level measurement and control.The introduction of foreign advanced technology and equipment for the production of new transmitters, key raw materials, components and parts are imported, the whole machine after rigorous assembly and testing, the level transmitter has an advanced design principle, easy to install and use, suitable for a variety of media; overload and anti-jamming ability, stable performance.
1. Input level transmitter should be cleaned once a month during the use;
2. Input level transmitter in the cleaning, you should first open the input water level meter iron pipe screw cap, carefully take out the liquid level meter, and then the liquid level meter attached to all the debris removed;
3. Clean input level transmitter water level meter pilot hole, can be trichloroethylene or alcohol into the pilot hole, injected into it to the height of one-half of the place, and thenSoak it for about 5 minutes, then shake it slightly, and repeat it many times until it is clean.It must be noted that do not use any apparatus to clean the pilot hole to prevent damage to the sensitive core pressure-sensitive diaphragm;
4. In cleaning the pressure interface and pilot hole of the input level transmitter, do not use brushes or metal tools with too much hardness to prevent damage to the sensitive core as well as the pressure interface threads;
5. All cleaned and then slowly put the poured out level meter back to the iron pipe, feel that it has been placed in the low part of the iron pipe, and then theThe screw cap can be installed back to the original place.
Categorization
Basic category
Input type, straight rod type, flange type, threaded type, inductive type, screw-in type, float type structure design, with anti-clogging type design, simple installation, easy to use, strong interchangeability, high quality sensors with high sensitivity, fast response speed, accurately reflecting the flow or static liquid level of the small changes in the measurement of high accuracy.
The product is characterized by advanced design principle, complete variety of specifications, easy installation and use.
The input level transmitter adopts high-performance diffusion silicon piezoresistive pressure sensor as the measuring element, and after highly reliable amplification processing circuit and precision temperature compensation, it converts the gauge pressure or absolute pressure of the measured medium into standard voltage or current signal.This product is compact in size, easy to use and install, directly into the water to the liquid level height.
Features: advanced circuit processing technology, stable performance, high sensitivity; a variety of ranges, up to 200m (water column pressure); 316L stainless steel isolation diaphragm, suitable for a variety of measurement media; flexible configuration, according to the need to choose different configurations.
Applications:Industrial field level measurement and control, urban water supply and sewage treatment petroleum, chemical, power plants, hydrological monitoring, reservoirs, dams, hydropower construction and other fields of liquid level measurement and control.
Features: reverse polarity and current limit protection; laser resistance temperature compensation, zero point, range can be adjusted on-site; wide range of corrosion resistance, suitable for a variety of media; overload and anti-interference ability, stable performance.
Input type
Input type hydrostatic level transmitter is based on the principle that the measured static pressure of the liquid is proportional to the height of the liquid, and adopts the piezo-resistive effect of diffusion silicon or ceramic sensitive elements to convert the static pressure into an electrical signal.After temperature compensation and linearity correction.Converted into 4-20mADC standard current signal output.
The sensor part of the input hydrostatic level transmitter can be directly put into the liquid, and the transmitter part can be fixed by flange or bracket, so it is very convenient to install and use.
Folded Silicon piezoresistive
The silicon piezoresistive liquid level transmitter measures the hydrostatic pressure proportional to the depth of the liquid level on the basis of the liquid level sensor, and converts it into the standard current and voltage signal output through the amplifier circuit, establishes the linear contrast relationship between the output electrical signal and the depth of the liquid level, and realizes the measurement of the liquid depth. In the structure, waterproof wire is used to seal the connection with the stainless steel shell, the ventilation pipe is communicated with the outside world in the cable, and the internal structure is anti-condensation design. With good stability and reliability, it is widely used in environmental protection, water conservancy, power plant, urban water supply and drainage, hydrological exploration and other fields of water level measurement and control.
Folding lightning protection
The anti-lightning level transmitter encapsulates the OEM oil-filled core in the stainless steel shell, the front protective cap protects the sensor diaphragm, and also enables liquid to contact the diaphragm smoothly. The waterproof wire is sealed with the shell, and the vent tube is communicated with the atmosphere in the cable internal structure to prevent condensation. The three-level lightning protection module is designed in the internal circuit, which can effectively prevent the damage of induced lightning.
Folding Armored
The product can be cut directly into the bottom of the liquid, measuring the height from the end of the sensor to the surface of the liquid level, easy to install, high reliability, suitable for open containers or need to be inserted into the installation of the liquid level measurement.
Category Selection
Level transmitter as a level measurement display instrument due to easy installation, high measurement accuracy, long service life and other characteristics in engineering applications has been widely used.Level transmitter in the daily use of more input level transmitter, single-flange level transmitter, double-flange level transmitter, radio frequency capacitance level transmitter and so on.
Characteristics and selection of level transmitters
1, Monoflange level transmitter
Monoflange level transmitter with flat flange and with insertion cylinder flange level transmitter, are the use of the measured medium of its own gravity to measure the height of the liquid level.Single flange level transmitter is suitable for viscosity, easy to crystallize the medium, generally used for open container or equipment installation.
2, Double flange level transmitter
Double flange level transmitter is a differential pressure transmitter, to avoid the measured medium directly with the transmitter isolation diaphragm contact provides a reliable measurement method.The main features are the need to isolate the high temperature medium from the transmitter, the measurement medium has a corrosive effect on the transmitter sensitive original, suspended liquid or high viscosity media, the measured medium due to environmental or process temperature changes and curing or crystallization, replacement of the measured medium need to be rigorously purify the measuring head and so on.Double flange level transmitter is mainly used in sealed pressure vessel level measurement.
3, Input level transmitter
Input level transmitter has rod type and range type, its principle is based on the principle that the measured static pressure of the liquid is proportional to the height of the liquid, using diffusion silicon or ceramic sensitive components of piezoresistive effect, the static pressure into an electrical signal.After temperature compensation and linearity correction, it is converted into 4-20mADC standard current signal output.Because this transmitter is easy to install, simple, adaptable and so on, from water, oil to the viscosity of the paste can be measured with high accuracy, not subject to the measured medium blistering, deposition and other influences, generally used for the installation of open containers or equipment.
4, Radio frequency capacitance level transmitter
Radio frequency capacitance level transmitter principle is when the probe level and conductive liquid constitutes a capacitor, in which the metal core of the probe line for the capacitance of one pole, the conductive liquid for the capacitance of the other pole, the middle of the high stability of the polytetrafluoroethylene, i.e., the insulating layer of the probe line as a medium between the two poles, along with the change in level, the liquid surrounded by the probe line of the area of the consequent change so as to constitute a capacitor.The relative area of the two poles change, when the liquid level rises, the capacitance will increase, the radio frequency circuit will be converted into an analog signal output.RF capacitor level transmitter is as simple to measure high temperature pressure vessel as normal temperature and pressure, and the measured value is not affected by the temperature of the measured liquid, specific gravity and the shape of the vessel, pressure.It is mainly used for liquid level measurement of acid and alkali, chloride, organic solvent, liquid CO2, ammonia, PVC powder, ash, oil-water interface, traditional Chinese medicine and so on.
