Cryogenic Level Sensor for Liquid Nitrogen Tank Level Indicator

The Cryogenic Level Sensor is a capacitance-based level transmitter for cryogenic liquid level measurement. Cryogenic Level Sensor is a customized product for liquid level measurement in low temperature environments such as liquid nitrogen, LNG, and liquid ammonia. Also called liquid nitrogen level sensor. This product has no moving parts and is not disturbed by the external environment. It has the advantages of long-term operation, high sensitivity, good linearity, low temperature resistance, etc. The cryogenic level sensor provides a variety of output signals. It is used in LNG liquid natural gas, petroleum, chemical industry, metallurgy, electric power, papermaking, pharmaceutical and other fields.

Cryogenic Level Sensor for Liquid Nitrogen Tank Level Indicator

Features of Cryogenic Level Sensor

  • Working temperature: -196℃-80℃
  • Working pressure: 0-32MPA
  • Power supply: 5V 12-24V
  • Output: RS232 \ RS485 \0-5V\4-20mA
  • The length of the sensor and the junction box part can be customized according to customer requirements.

Remarks: The picture of this product does not represent the appearance of the product, everything is subject to the actual product

Extended reading: Low temperature Turbine Flowmeter-The Best Liquid Nitrogen Flow Meter

Technical Parameters

1Operating VoltageDC 10V~30Vcustom made
2Probe working temperature-196℃~80℃custom made
3ambient temperature-40℃~80℃——
4scope of testcustom madecustom made
5Pressure range——Special can be customized
6Probe diameterΦ16custom made
7Installation methodcustom-madeSpecial can be customized
8Explosion-proof grade304 metal shellcustom made
9Precision class2.0/3.0Customized type is subject to use
10Analog output0~5V/RS232/RS485 /0-3.3VSpecial can be customized

Extended reading: Nitrogen(N2) Flow Meter Types

Liquid Nitrogen Level Measurement and Control

The intelligent control system of liquid nitrogen tank is based on ultra-low temperature application technology. It adopts the design method from qualitative to quantitative. It integrates the integrated application system of liquid nitrogen monitoring, equipment control, data communication, computer and alarm.

The liquid nitrogen tank intelligent control system uses technological means such as networking, communication, database, cloud storage, etc. to provide users with intelligent solutions that serve the entire life cycle of liquid nitrogen tank control.

Extended Reading:

Laser Level Transmitter is a large-range, high-accuracy explosion-proof level measurement product supplied by Sino-Inst.

The liquid nitrogen tank automatic liquid supply system solution can realize the control, monitoring, monitoring and fault diagnosis of all aspects of the entire liquid nitrogen supply system. Meet the requirements of liquid nitrogen tank intelligent control system for liquid supply system in various fields. Including liquid nitrogen residual monitoring, centralized liquid supply, separate liquid supply, fault diagnosis and alarm and system information integration and other requirements.

The system has powerful monitoring functions, data calculation and analysis and diagnosis capabilities. It can realize mutual communication control between various devices.

Read More About: Monitoring liquid volume solutions

Differential Pressure Measurement for Cryogenic Tanks

The differential pressure transmitter is difficult to measure the liquid level of the medium below -20℃. If it is necessary to measure the liquid level of low-temperature media such as liquid ammonia and liquid nitrogen, indirect measurement of gas isolation can be used.

As shown in the figure, the purpose of measuring the liquid level of low temperature medium is achieved by measuring the gas pressure in the pressure guiding pipe.

Because the liquid in the high-pressure side pressure guiding pipe is in a normal temperature state above the boiling point.

Therefore, the liquid in the pressure guiding tube evaporates into gas until saturated gas is formed in the pressure guiding tube.

The differential pressure transmitter should be installed above the maximum liquid level. The high pressure side is connected to the liquid phase pressure guiding pipe. Not only can the transmitter be in a working environment at room temperature, but also the low-temperature liquid can be fully vaporized.

In order to easily adjust the zero position of the instrument and replace the instrument, a balance valve should be installed between the high and low pressure sides of the differential pressure transmitter.

After the differential pressure transmitter is installed, the zero position should be adjusted, then the gas phase pressure pilot valve PL should be opened, and the zero position should be adjusted again under the working pressure.

Then open the liquid phase pressure pilot valve PH. Wait for a while for the cryogenic liquid to fully vaporize. Then close the balance valve to put the transmitter into operation.

When checking or adjusting zero during use, first open the balance valve to balance the pressure on the high and low pressure sides of the differential pressure transmitter, and then close the liquid phase pressure guide valve to check or adjust the zero position.

If the vaporized gas of the liquid to be tested is dangerous in contact with the air, certain safety measures should be taken during maintenance.

Differential pressure type level transmitter working principle

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The Most Common Types Of Level Indicators

Principle: The principle of the connector. Developed according to the principle of buoyancy and magnetic coupling.

When the liquid level in the container under test rises and falls. The permanent magnet steel in the float is transmitted to the magnetic flip column indicating panel through magnetic coupling. Flip the red and white columns over 180°.

The column turns from white to red when the liquid level rises.
The column turns from red to white when the liquid level drops.

The junction of red and white on the panel is the actual height of the liquid level in the container, so as to realize the liquid level display.

The structure of the float level meter is mainly designed and produced based on the principles of buoyancy and static magnetic field.

The position of the float with a magnet (abbreviated as float) in the measured medium is affected by buoyancy: changes in the liquid level lead to changes in the position of the magnetic float.

The magnet and sensor (reed switch) in the floating ball act to change the number of components (such as fixed-value resistors) connected in series to the circuit, thereby changing the electrical quantity of the instrument circuit system.

That is, the change of the position of the magnetic float causes the change of the electrical quantity.

The liquid level in the container is reflected by detecting the change of the electrical quantity.

Extended Reading: What is level transmitter working principle?

It is designed and manufactured using the principle of mechanical balance.

When the liquid level changes, the original mechanical balance will reach a new balance through the movement of the steel belt under the disturbance of the buoyancy of the float.

The liquid level detection device (float) drives the steel belt to move according to the liquid level. The displacement transmission system drives the transmission pin to rotate through the movement of the steel belt. It then acts on the counter to display the liquid level.

The radar level meter 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 emits high-frequency pulses and propagates along the cable probe. When the pulses meet the surface of the material, they are reflected back and received by the receiver in the instrument. The distance signal is converted into a level signal.

Extended Reading: Influence of Dielectric Constant on Liquid Level Measurement | Radar-Guided Wave Radar Level Meter

When the sensor of the magnetostrictive level transmitter works, the circuit part of the sensor will excite a pulse current on the waveguide wire. When the current propagates along the waveguide wire, a pulse current magnetic field will be generated around the waveguide wire.

There is a float outside the sensor rod of the magnetostrictive liquid level gauge. This float can move up and down along the rod with the change of the liquid level.

Inside the float there is a set of permanent magnetic rings.

When the magnetic field of the pulse current meets the magnetic field of the magnetic ring generated by the float, the magnetic field around the float changes so that the waveguide wire made of magnetostrictive material generates a torsional wave pulse at the position of the float. The waveguide wire is returned and detected by the detection mechanism.

By measuring the time difference between the pulse current and the torsional wave, the position of the float, that is, the position of the liquid surface, can be accurately determined.

Extended reading: Oil-water interface measurement-Magtech magnetic level indicator

The radio frequency admittance level meter is composed of a sensor and a control instrument. The sensor can be installed on the roof of the warehouse using rod-type, coaxial or cable-type probes.

The pulse card in the sensor can convert the material level change into a pulse signal and send it to the control instrument. After the control instrument is processed and converted into engineering quantity and displayed, it realizes the continuous measurement of the material level.

Read more about: Capacitive Level Measurement System

The working principle of the tuning fork level controller is to make the tuning fork vibrate at a certain resonance frequency through a pair of piezoelectric crystals installed on the tuning fork base.

When the tuning fork is in contact with the measured medium, the frequency and amplitude of the tuning fork will change. These changes are detected, processed and converted into a switching signal by an intelligent circuit.

The glass plate type liquid level meter is connected to the container through the flange to form a communication device, and the height of the liquid level in the container can be directly read through the glass plate.

The pressure level transmitter adopts the principle of static pressure measurement.

When the liquid level transmitter is put into a certain depth in the measured liquid.

At the same time as the pressure on the liquid surface of the sensor, the pressure of the liquid is introduced into the positive pressure chamber of the sensor through the air-conducting stainless steel. Then the atmospheric pressure Po on the liquid surface is connected to the negative pressure chamber of the sensor to offset the Po on the back of the sensor.

The pressure measured by the sensor is: ρ .g.H , and the liquid level depth can be obtained by measuring the pressure P .

Capacitive level meters measure the level of liquid level by measuring changes in capacitance.

It is a metal rod inserted into the liquid container. The metal rod is used as one pole of the capacitor. The wall of the container is used as the other pole of the capacitor.

The medium between the two electrodes is the liquid and the gas above it.

Because the dielectric constant ε1 of the liquid and the dielectric constant ε2 on the liquid surface are different. For example: ε1>ε2.

Then when the liquid level rises, the total dielectric constant value between the two electrodes of the capacitive liquid level gauge increases accordingly and the capacitance increases.

Conversely, when the liquid level drops, the value of ε decreases, and the capacitance also decreases.

Therefore, the capacitive liquid level meter can measure the level of the liquid level through the change of the capacitance between the two electrodes.

The intelligent electric displacer liquid level meter is a liquid level measuring instrument designed according to Archimedes’ law and the principle of magnetic coupling. The instrument can be used to measure the liquid level, boundary level and density, and is responsible for the output of upper and lower limit alarm signals.

It is designed and manufactured using the principle of mechanical balance.

When the liquid level changes, the original mechanical balance will be disturbed by the buoyancy of the float. The new balance will be achieved by the movement of the steel belt (rope).

The liquid level detection device (float) drives the steel belt (rope) to move according to the liquid level. The displacement transmission system drives the on-site indicating device through the movement of the steel belt (rope), and then displays the liquid level on the display device.

The pontoon is submerged in the liquid in the pontoon chamber and is rigidly connected to the torsion tube system. The force on the torsion tube system is the net weight of the pontoon minus the buoyancy on the pontoon. Under the action of this combined force, the torsion tube is twisted by a certain angle.

Changes in the position, density or boundary level of the liquid in the buoyancy chamber cause the buoyancy force of the buoyancy immersed in the liquid to change, so that the twisting angle of the tube also changes.

This change is transmitted to a sensor rigidly connected to the torsion tube. Change the sensor output voltage. Then it is amplified by electronic components and converted into 4-20mA current output.

Displacer level transmitters use microcontrollers and associated electronics to measure process variables. Provides current output. Drive LCD display and provide HART communication capability.

The magnetic-sensitive electronic two-color liquid level meter is made of high-quality stainless steel and imported electronic components.

The display part adopts high-brightness LED two-color light-emitting tube to form a columnar display screen.

Through the red and green changes of the LED light column, the upper and lower limit alarm and control of the liquid level can be realized.

The external liquid level meter is an instrument that measures the liquid level from the outside of the container using the principle of sonar ranging and “micro-vibration analysis” technology.

Two small external level gauge ultrasonic sensors are installed on the bottom of the tank and the other on the side wall of the tank to compensate for density changes.

The signal of the external level meter sensor is converted by the microprocessor and output to the local display or user control system. Can calculate the height of the liquid in the tank and the volume of the liquid in the tank

The hydrostatic level transmitter encapsulates the diffused silicon oil-filled core in a stainless steel shell.

The front protective cap protects the sensor diaphragm. It can also make the liquid contact the diaphragm smoothly. The water wire is sealed with the housing. The ventilation tube is connected to the outside world in the cable. The internal structure is designed to prevent condensation.

Ultrasonic level Sensor is composed of a complete ultrasonic sensor and control circuit.

The ultrasonic wave emitted by the ultrasonic sensor is reflected by the liquid surface. The time required to return is used for calculation.

The temperature influence in the ultrasonic transmission process is corrected by the temperature sensor, which is converted into the distance between the liquid surface and the ultrasonic sensor.

Output 4mA-20mADC analog signal through LCD screen. Realize remote reading of field instruments.

Read More about: How to Choose Explosion Proof Ultrasonic Level Sensor?

The differential pressure liquid level transmitter is an electrical component that measures the high and low pressure difference, and then converts it into a current signal by the conversion component and transmits it to the control room.

Differential pressure liquid level transmitter is mainly used for liquid level measurement of closed pressure vessels.

The size of the differential pressure also represents the size of the liquid level height.

Use a differential pressure gauge to measure the differential pressure between the gas and liquid phases to know the liquid level.

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The general liquid nitrogen tank can have its own liquid level indicator.
Some industrial liquid nitrogen storage tanks, without liquid level display, can be equipped with our very low temperature liquid nitrogen liquid level sensor. Local display is supported. At the same time, it supports signal output, which can be connected to the recorder or the user’s monitoring system.

Extended reading: Nitrogen Gas Rotameter

The design temperature of the liquid nitrogen tank is -196°C. There are two kinds of conventional pressures designed, one is 0.8MPa and the other is 1.6MPa. These two design pressures are based on usage needs.

When nitrogen is under pressure, the temperature reaches -196°C. It will become a dark blue liquid, which is liquid nitrogen. Liquid nitrogen can be stored under pressure or without pressure.

Of course, users can also measure the pressure for liquid nitrogen storage tanks according to their own needs. Just use our Cryogenic Pressure Transducer.

If you want to divide the level sensor into two categories. Then it can be divided into contact type and non-contact type liquid level sensor according to the measurement of whether it is released from the medium.

Extended reading: Non Contact Level Transmitters: Types & Industrial Applications

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.

Read more about: What is level transmitter working principle?

Sino-Inst is Manufacturer of Cryogenic Level Sensors for Liquid Nitrogen Tank Level Indicator. We supply more than 10 kinds of liquid nitrogen measure instruments.

Cryogenic Level Sensors are mainly used for level measurement of low temperature liquids.
It can measure even liquids such as Liquid Nitrogen, Liquid Oxygen, etc.

Cryogenic Level Sensors enable stable level measurement. This greatly meets the measurement needs of many applications. Can be used from small to large tanks.

Sino-Inst’s Cryogenic Level Sensors, made in China, Having good Quality, With better price. Our level measurement instruments are widely used in China, India, Pakistan, the US, and other countries.

The entire team at Sino-Inst’s has received excellent training, so we can ensure that every client’s needs are met. For assistance with your product requirements, whether it’s a Cryogenic Level Sensor, flow sensor, or other device, give us a call.

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This entry was posted in Level Measurement Solutions, Blog, Capacitive Level by KimGuo11. Bookmark the permalink.

About KimGuo11

Wu Peng, born in 1980, is a highly respected and accomplished male engineer with extensive experience in the field of automation. With over 20 years of industry experience, Wu has made significant contributions to both academia and engineering projects. Throughout his career, Wu Peng has participated in numerous national and international engineering projects. Some of his most notable projects include the development of an intelligent control system for oil refineries, the design of a cutting-edge distributed control system for petrochemical plants, and the optimization of control algorithms for natural gas pipelines.