Level Transmitters, also called level gauges. Level transmitters are instrument that provide contact and non-contact level measurement. Level transmitter consists of sensor and eletrical transmitter. For continuous level measurement and point level detection in liquids and bulk solids. Levels in liquids, pastes, bulk solids or liquefied gases are often measured in tanks, silos or movable containers. Level transmitters have: magnetostrictive, radar, guide wave, ultrasonic, DP, and Hydrostatic types. Differential pressure transmitter with the capillary and diaphragm is a more economical choice. And magnetostrictive level transmitter is often used to measure the level of oil (diesel, fuel). If you have any questions about product selection, please feel free to contact us. We provide free technical guidance.
What is a Level Transmitter?
A Level Transmitter is sensor and eletrical transmitter, that provides continuous level measurement. Level transmitters can be used to determine the level of a given liquid or bulk-solid at any given time. This is different to a level switch which only alarms when the level of material (liquid or bulk-solid) reaches a predetermined level. Capacitive, radar, submersible, and ultrasonic are the different types available of level transmitters.
Level measurement transmitters are used in a myriad of applications that require level measurement within containers or tanks. Levels of media such as water, viscous fluids, and fuels, or dry media such as bulk solids and powders can be measured using the transmitter.
How many types of level transmitters are there?
There are 7 main types of level transmitters that Sino-Instrument offers. Each type of transmitter works in a different way, and makes it useful for different types of processes.
Types of Level Transmitters:
Magnetostrictive level transmitter,in-tank liquid level transmitter, is a continuous magnetic level gauge. The magnetostrictive level sensor, measure the level of fluid in the vessel. By detecting the level of the magnets contained within the float and then transmits the measurement back to the control system.
Magnetic Float level sensors are continuous level sensors featuring a magnetic float that rises and falls as liquid levels change. The movement of the float creates a magnetic field that actuates a hermetically sealed reed switch located in the stem of the level sensor, triggering the switch to open or close.
Ultrasonic Level Indicator, also called Ultrasonic level sensor, or ultrasonic level transmitter. In this type of transmitter, an ultrasonic transducer is mounted at, or near the top of a container containing liquid. The transducer sends out an ultrasonic pulse. The pulse hits the surface of the liquid, and gets reflected. The sensor then calculates the fill level based on the time between the transmitted and received signal.
Hydrostatic level transmitters, also called submersible level transmitter, or pressure level transmitters. For Hydrostatic level measurement, Continuous level measurement in liquid applications with pressure sensors. These transmitters help in determining fluid level of a container. By measuring the pressure of resting body of the fluid within it.
Radar level transmitter, also called Radar level gauge. Non-contact Continuous level measurement in liquids and solids with free space radar sensors. Non-contacting radar, based on microwave technology, detects only surfaces that reflect energy. These transmitters work on the principle of a radar by using radio wave emissions. Mounted at the top of a tank filled with a liquid. The transmitter sends a radar signal into the liquid, and receives a reflection of the signal. The transmitters then analyze the current fill level of the tank based on the time taken by the transmitted signal to return.
Guided Wave Radar (GWR) Level Transmitters, also called wave guided radar level transmitter. Using guided wave radar technology, GWR level transmitters have no moving parts. They can measure both level and the interface between two media. Continuous level measurement in liquids and solids with guided wave radar sensors. These transmitters work by sending a microwave pulse through a sensor cable or rod. The signal hits the surface of the liquid, and travels back to the sensor, and then to the transmitter housing. Based on the time taken by the signal to travel down the sensor and back up again. The electronics integrated in the transmitter housing determine the filling level.
Differential Pressure (DP) Level Measurement uses pressure readings and specific gravity to output level. DP Level is a common measurement technique that is used in a wide variety of applications. Solutions include standard transmitter connections and integrated transmitters with direct or remote mount seals that can be configured in tuned, balanced, and electronic systems. Additional Wireless options are also available.
Capacitance level detectors, also known as Capacitance level transmitter. RF Capacitance Level Transmitter offers continuous and point level detection. In liquids and solids with capacitance probes. These transmitters use liquid stored in a tank or container as a dielectric medium between two or more electrodes. The energy capacity of the capacitor circuit increases when there is more liquid, and decreases if there is less liquid. Measuring the variations in the capacitance value, capacitance level transmitters calculate level of the tank.
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Q & A
What does a level transmitter do?
The level of the liquid medium in the container is called the liquid level. And the instrument that measures the liquid level is called the liquid level transmitter. Level transmitter is a kind of level instrument. There are two types of level transmitterss, one is continuous and the other is point-off. The continuous level transmitter is a real-time monitor of the height of the liquid in the container. The point type, which generally takes two points, high and low, and outputs an alarm signal when the medium in the container reaches these two points.The types of liquid level transmitters is very wide. Specific include: magnetic flap liquid level gauge, tuning fork vibration type, differential pressure type, pressure type. Ultrasonic, magnetostrictive liquid level gauge, magnetic flap, radar and so on.
Levels of media such as: water, viscous fluids, and fuels, or dry media such as bulk solids and powders can be measured using the transmitter.
Level measurement transmitter are used in a myriad of applications that require level measurement within containers or tanks. These transmitters often find their application in material handling, food and beverage, power, chemical, and water treatment industries.
What is level transmitter working principle?
Let’s take a closer look at how different types of level transmitters work.
The magnetostrictive transmitter is a liquid level signal. Magnetostrictive transmitter couples the magnetic subsystem and transmits pulses at intervals of 1.5 μs. To accurately measure the position of the magnetic float in the level gauge.The magnetic field generated by this pulse is conducted down the waveguide.When the magnetic field of the magnetic float meets the pulsed current magnetic field, a “return” pulse (also called “waveguide twist pulse”) is generated.The sensor detects this “return” pulse.According to the time between the current pulse and the “return” pulse. The position of the float is calculated by the single-chip microcomputer. To determine the measured liquid level or boundary.The SI-100 series is suitable for applications where high measurement accuracy is required.It is also suitable for remote transmission of high temperature magnetic flip column level gauge.The transmitter outputs two-wire, three-wire 4-20mA DC signals, compatible with HART communication protocol.One product can pass two magnetic floats, simultaneously measure the liquid level and boundary in the tank. And output two independent 4-20mA liquid level and boundary signals, in two separate junction boxes.
The probe launches a bunch of ultrasonic pulse to the object. Ultrasound is reflected by the object surface. Then received through the probe. At the same time the electronic unit computing time and conversion it. Thus we can know the corresponding measured distance.This product is the non-contact measurement, high precision, strong anti-interference. Operate in the most demanding environmental conditions: dust, smoke, electromagnetic interference, strong corrosion, etc.Widely used in chemical, petroleum, metallurgy, coal. Building materials, paper making, environmental protection industry and so on.Ultrasonic can spread effective in lots of occasions,Such as storage tank, materials trough, pool, well, drains, measuring boxes, granaries, silo, etc.
Submersible level transmitters require rigorous design and construction standards for long service life;Sino-Instrument submersible transmitters are fully sealed. To meet IP68 and NEMA 6P ratings for permanent submersion.They are equipped with a vented cable to allow compensation, for changes in barometric pressure. And they are suitable for submersion up to 200m.While moisture protection is crucial, many transmitters are also subjected to physical stress and caustic environments. Including turbulence and corrosive chemicals.The transmitters’ durable stainless steel construction provides superior protection for extended use.While submersible transmitters are commonly utilized in clean-water applications. They are also applicable for use in holding tanks, lift stations, wet wells, chemical plants, and rivers.The submersible transmitters are equally reliable sensing devices, for refineries an.d paint plants. And they may also be used with distillation equipment, filling equipment for combustible gases, and overfilling protection systems.
Antenna system to launch and microwave receiving energy is a very low, very short pulse.Radar waves travel with the speed of light. The running time can be through the electronic components are converted into a signal.Measurement of this special time extension method can realize stable, accurate in a very short period of time.Even if the condition is very complex, the presence of false echo, with the latest micro-processing technology and debugging software. Also can analyze the level echo accurately.Microwave antenna to receive the reflected pulse, and transmitted to the electronic circuit. A microprocessor to signal to process to identify the micropulse generated on the material surface echo.Echo recognition is completed by the pulse system, the accuracy can reach the millimeter level.From the material surface distance between D and T pulse is proportional to the time travel:D=C×T/2Where C is the speed of lightBecause of the air tank is a known distance E, L:L=E-DBy setting the empty tank height E (= zero), the full height of F (= full scale) and some application parameters. Application parameters automatically make the instrument to measure the environment. 4 – 20mA with corresponding output.
Differential pressure level transmitters, are commonly used to measure the level of liquid in a closed container. U.sing the pressure difference created by the gravity of the liquid, to measure the level of liquid in the container.The high-pressure side measuring tube (above the figure), is always filled with water due to steam condensation. Keeping the pressure constant, while the low-pressure side measuring tube (located below the figure) forms a communication device with the container. And the pressure changes with the liquid level in the container.Then there are:P+=P0+ρgh1+ρghP-=P0+ρgh2+ρgh△P=P+-P-=ρgh1-ρgh2When the liquid level changes from h2=0 to h2=h1,the differential pressure measured by the differential pressure transmitter,changes from the maximum value to ΔP=0.By setting the transmitter, the output current is changed from 4-20mA.
The principle of capacitive level measurement, is based on the capacitance change of a capacitor.
The probe and the tank wall form a capacitor, whose capacitance is dependent on the amount of product in the tank:
An empty tank has a lower, a filled tank a higher capacitance.
A simple capacitor consists of two electrode plate, separated by a small thickness of an insulator, such as solid, liquid, gas, or vacuum.
This insulator is also called as dielectric.Value of C depends on dielectric used, area of the plate and also distance between the plates.
C = capacitance in picofarads (pF)
E = a constant known as the absolute permittivity of free space
K = relative dielectric constant of the insulating material
A = effective area of the conductors
d = distance between the conductors
This change in capacitance can be measured using AC bridge.
Levelflex works with high-frequency radar pulses, which are emitted and guided along with the probe.As the pulse meets the medium surface, part of the emitted pulse is reflected due to a change of the dc value (relative dielectric constant).The Time-of-Flight between pulse launching and receiving is measured. And analyzed by the instrument and constitutes a direct measure for the distance. Between the process connection and the product surface.
What is a radar level transmitter?
Radar level transmitter is a kind of liquid level transmitter which uses the principle of radar operation.
Radar Level Sensor also called radar level transmitter, are the indicating transmitter for liquid level.
Non-contact Continuous level measurement in liquids and solids with free space radar sensors.
RADAR (Radio Detection And Ranging) is a device which can detect the presence of faraway objects by obtaining a reflection of electromagnetic waves emitted from the device itself. Although invented much earlier, wide deployment of radar was done by Britain during the Second World War to detect oncoming German bombers.
Radar level measurement is a safe solution. Even under extreme process conditions (pressure, temperature) and vapors. Various antenna versions for every kind of radar applications are available.
In continuous non-contact level measurement with radar, the sensor sends microwave signals towards the medium from above. The surface of the medium reflects the signals back in the direction of the sensor. Using the received microwave signals, the sensor determines the distance to the product surface and calculates the level from it.
What is the difference between level switch and level transmitter?
Liquid level transmitter: It is used for liquid level measurement. It converts the change of liquid level into the corresponding 4 ~ 20ma current signal. And transmits it to the operation room for display, control and other operations.
Liquid level switch: It is used for liquid level alarm or interlock. It sets a value in advance (for alarm or interlock). If the high level value is set to 80%, then when the liquid level reaches the set value (Ie at 80%). Output a digital signal as an alarm or interlocking signal source.
Level Transmitter Price
When choosing a level transmitter, we must first understand what our measurement conditions are like.
What is the measurement range?
What is the measurement medium?
What is the measurement pressure?
What is the measurement temperature?
Does it need explosion protection?
Are there any material requirements?
Do you need a local display?
What is the installation method and installation size?
Signal output requirements?
Then we choose which type of level transmitter is suitable for our level measurement. If you have difficulty in product selection, please feel free to contact us!
Based on the product selection, we can determine the price of the level transmitter. Sino-Instrument is a manufacturer of level transmitters, so we offer the best price.
For example: The reference price of a differential pressure level transmitter is around USD 400.
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