Explosion Proof Ultrasonic Level Sensor| Hazardous Area-Non Contact

Explosion proof ultrasonic level sensor is a non-contact, easy to install and maintain liquid level measurement instrument.

It is used to measure flammable and explosive liquids such as diesel oil and crude oil. Or used to measure the height of liquids in explosion-proof environments. It is widely used in explosion-proof environments such as oil exploration, oil refining, chemical industry, and medicine.

Explosion Proof Ultrasonic Level Sensor

Featured Explosion Proof Ultrasonic Level Sensors

Intrinsically Safe/Explosion Proof

It is often necessary to use explosion-proof instruments in industrial sites. The general industrial explosion-proof instruments are mainly explosion-proof and intrinsically safe. So, how to understand the difference between them?

Flameproof definition:

It can withstand the explosive pressure of internal explosive gas mixture. And can prevent the internal explosion from spreading to the explosive mixture around the enclosure of electrical equipment enclosure (zone I explosion-proof technology).

Dangerous gases are allowed to enter the flameproof enclosure, which may cause an explosion. However, the enclosure must have sufficient strength. And each shell joint surface must have a sufficiently long engagement length and a sufficiently small gap. To ensure that the internal explosion will not pass through the flameproof joint and cause the external environment to explode.

Clearance explosion-proof technology. Rely on the gap and mesh length to achieve the effect of cooling and flameout.

Definition of intrinsic safety:

Any electric spark or any thermal effect generated under the conditions specified in the standard (including normal operation and specified fault conditions) cannot ignite the circuits in the specified explosive gas environment (Zone 0/I explosion-proof technology).

It is a “safe” technology that uses suppression of ignition source energy as an explosion-proof method. It is required that the electric spark or thermal effect that the equipment may produce under normal operation or failure state are respectively less than the minimum ignition energy and self-ignition temperature of the explosive dangerous gas. For example: hydrogen 19uJ 560℃.

Intrinsically safe technology is actually a low-power design technology. Therefore, it can be well applied to industrial automation instruments.

Explosion-proof applicable area: It can only be installed in hazardous locations in Zone 1 or Zone 2.

Intrinsically safe application area:

Exia: Equipment that can maintain explosion-proof performance until two components or other types of failures. Intrinsically safe equipment can be installed in hazardous locations in Zone 0, Zone 1, and Zone 2. Exia intrinsically safe equipment is the only explosion-proof electrical equipment that can be installed in zone 0.

Exib: Equipment that can maintain explosion-proof performance until a component or other type of failure. Intrinsically safe equipment can be installed in hazardous locations in Zone 1 and Zone 2.

Extended Reading: How many types of level transmitters are there?

Read more about: What Is the Difference Between Class 1 Div 1 and Class 1 Div 2 ?

Two-wire Explosion Proof Ultrasonic Level Sensor

  • Measurement range: 5m, 10m, 15m, 25m (selected according to the actual measurement range)
  • Blind area: 0.25m~0.8m
  • Ranging accuracy: 0.25% to 0.5% (standard conditions)
  • Ranging resolution: 1mm
  • Pressure: Below 4 atmospheres
  • Instrument display: Built-in LCD to display liquid level or space distance
  • Analog output: 4~20mA
  • Digital output: none
  • Power supply voltage: DC24V/1W, built-in lightning protection device
  • Ambient temperature: -20℃~+60℃ High temperature needs to be customized (customizable temperature resistance 90℃)
  • Protection class: IP65 or IP68

Extended reading: Case Study: Automatic Sludge Blanket Level Detector

Four-wire Explosion Proof Ultrasonic Level Sensor

  • Measurement range: 5m, 10m, 15m, 25m (selected according to the actual measurement range)
  • Blind area: 0.25m~0.8m
  • Ranging accuracy: 0.25% to 0.5% (standard conditions)
  • Ranging resolution: 1mm
  • Pressure: Below 4 atmospheres
  • Instrument display: Built-in LCD to display liquid level or space distance
  • Analog output: 4~20mA
  • Digital output: RS485, Modbus protocol or custom protocol
  • Relay output: two independent outputs
  • Power supply voltage: DC24V/AC220V, built-in lightning protection device
  • Ambient temperature: -20℃~+60℃ High temperature needs to be customized (customizable temperature resistance 90℃)
  • Protection class: IP65 or IP68

More about Factors To Consider When Choosing Explosion Proof Ultrasonic Level Sensors.

External Explosion Proof Ultrasonic Level Sensor

  • Range specifications optional: 3m, 5m, 10m, 20m, 30m
  • Display resolution: 1mm
  • Short time repeatability: 1mm
  • Measurement error: ±1‰FS (too thick tank wall, unstable pressure and temperature may affect the accuracy)
  • Migration amount: ±10 m
  • Current output: 4~20mA, maximum load 750Ω
  • Communication: RS-485, infrared interface
  • The ambient temperature of the liquid level gauge host: -30℃~+70℃
  • Ultrasonic probe using ambient temperature: -50℃~+100℃, (wide temperature probe can be provided according to customer needs)
  • Operating environment humidity: 15%~100%RH
  • Explosion-proof mark: Ex d IIC T6 Gb
  • Shell protection: IP67
  • Liquid level display: 6-digit OLED display (unit: m)
  • Blind zone: There is a measurement blind zone in the ultrasonic level gauge

Extended reading: Non contact level measurement

Ultrasonic Level Sensor Working Principle

The working principle of the ultrasonic liquid level sensor is:

Ultrasonic transducer (probe) emits high-frequency pulse sound waves, and the surface of the measured level (material) is reflected back. The reflected echo is received by the transducer and converted into an electrical signal. The propagation time of the sound wave is proportional to the distance from the sound wave to the surface of the object.

The relationship between the sound wave transmission distance S and the sound speed C and the sound transmission time T can be expressed by the formula: S=C×T/2.

The probe part emits ultrasonic waves, which are then reflected by the liquid surface. The probe part is received again. The distance from the probe to the liquid (object) surface is proportional to the elapsed time of the ultrasonic wave:
hb = CT2
Distance [m] = time × speed of sound/2 [m]
The temperature compensation formula of sound velocity:
Ambient sound velocity = 331.5 + 0.6 × temperature

Extended reading: Amazing Solutions for Continuous Liquid Level Measurement

Ultrasonic Level Sensor for Tanks

Ultrasonic fuel tank level sensor, also called non-contact fuel meter. Ultrasonic level sensor measure continuous liquid level, fluid level, or oil level.

Ultrasonic level sensors measure the distance between the transducer and the surface. Using the time required for an ultrasound pulse to travel from a transducer to the fluid surface and back (TOF).  These sensors use frequencies in the tens of kilohertz range; transit times are ~6 ms/m.  The speed of sound (340 m/s in air at 15 degrees C, 1115 fps at 60 degrees F) depends on the mixture of gases in the headspace and their temperature.

More about Ultrasonic level measurement

Ultrasonic sensors work without the need to touch the medium being measured. Ultrasonic sensors are ideal for difficult or corrosive liquids such as acids, wastewater, and others. Ultrasonic level sensors are also ideal for continuous level measurement. While float switches and other sensors are adept at measuring when liquid levels are above or below a certain point. The nature of ultrasonic level measurement is such that levels can be sensed and displayed in real-time.

Read more about: Top 5 Ultrasonic Level Sensor Applications

Features of Ultrasonic Tank Level Sensor

  • Non-contact – nothing touches the liquid
  • Easy to install at the top of the tank into standard fittings
  • Use indoors or outside, in metal or plastic tanks
  • Connects to other industrial equipment
  • Measures a wide variety of liquids and liquid environments
  • Accessories to display, alarm, and control liquid levels
  • Wireless option sends tank levels to a LAN or the cloud
  • MRO & OEM tank setup duplication without re-calibration

Read more about: Ultrasonic Tank Level Sensor-External Mounted


Application variables to avoid using ultrasonics are extreme foam, vapor, turbulent flow or installation in tall fittings with narrow risers.

Foam, steam and turbulence can absorb and/or deflect most of the return signal.

Tall riser fittings can disrupt the acoustic signal path. Proper product selection and installation is important.

Extended reading: Ultrasonic Oil Level Sensor-External Paste-Truck Fuel Tank

The reason for the measurement failure of Ultrasonic Level Sensor is that the measurement distance of the ultrasonic level gauge refers to the calm liquid level. When the liquid level in the container fluctuates or is stirred, the liquid level is not calm and the reflected signal will weaken. to less than half of the normal signal, so the measurement value of the ultrasonic level gauge will be disturbed.

We want to eliminate the influence of agitation in the container on Ultrasonic Level Sensor measurement. We need to choose an ultrasonic level gauge with a larger range. If the actual range is 5 meters, use an ultrasonic level gauge with a range of 10 meters or 15 meters to measure.

If the Ultrasonic Level Sensor is not replaced, and the liquid in the tank is non-viscous. A still-pipe can also be installed. Place the Ultrasonic Level Sensor probe in the still-pipe to measure the height of the level gauge. Because the liquid level in the waveguide is basically stable. At the same time, it is recommended to change the two-wire Ultrasonic Level Sensor to a four-wire one.

Extended reading: Magnetostrictive Level Transmitter Working Principle

The ultrasonic sensor is an ultrasonic pulse signal sent by an ultrasonic probe, which propagates in the gas and is reflected after encountering the interface between the air and the liquid. high.

Extended reading: Radar Level Sensor Working Principle

More Explosion Proof Transmitters

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Sino-Ins offers 20 Explosion Proof Ultrasonic Level Sensors products.

About 13% of these are ultrasonic level transducers, 4% are ultrasonic level indicators.

A wide variety of Explosion Proof Ultrasonic Level Sensor options is available to you, such as free samples, paid samples.

Sino-Inst is an Explosion Proof Ultrasonic Level Sensor supplier, located in China.

Explosion Proof Ultrasonic Level Sensor products are most popular in North America, Mid East, and Eastern Europe.

The United States, and India, which export 99%, 1%, and 1% of ultrasonic level transmitters respectively.

You can ensure product safety by selecting from a certified supplier, with ISO9001, ISO14001 certification.

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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.