4 Most Common Types of Gas Sensors

The presence of toxic or explosive gases is a common enemy in most global and manufacturing industries.

Industries are increasingly required to respond to incidents with the risk of exposure to explosive atmospheres, low or enriched oxygen, or lethal toxic vapors.

Gas detection is fundamental to emergency response, and the core element in each gas detector is the sensor. Today, I will explain the four most common types of gas sensors.

What are Gas Sensors?

Gas sensors detect specific gases and measure the presence and concentration of gases in the air surrounding the sensor.

They are essential in safety systems, providing information on combustible, flammable, and toxic gases, as well as the area’s oxygen consumption and carbon dioxide proportions.

What are the Most Common Types of Gas Sensors

Catalytic bead sensors

Common Types of Gas Sensors

Catalytic bead sensors, a crucial tool in gas detection, are specifically designed to detect combustible gases.

They use a heated wire to detect a wide range of flammable gases, from natural gas leaks to gasoline spills.

In catalytic combustion, power is applied to a special wire coil in much the same way as a traditional light bulb.

Any combustible gas exposed to the sensor will react on the wire surface, producing a display reading.

 These detectors are commonly used to detect combustible gases. 

  • Methane (CH4)
  • Propane (C3H8)
  • Butane (C4H10)
  • Hydrogen (H2)
  • Acetylene (C2H2)

Advantages of catalytic bead sensors

A catalytic combustion gas sensor selectively detects flammable gas; it does not respond to anything that cannot be burned.

The response is fast, the service life is longer, and it is less affected by temperature, humidity, and pressure.

The sensor’s output is directly related to the environment’s explosion hazard, making it a leading sensor in safety detection.

Disadvantages of catalytic bead sensor

There is no selectivity. It will detect all flammable gases. The sensor is susceptible to poisoning, and most elemental organic vapors poison the sensor.

Electrochemical sensors

Electrochemical sensors are used in the gas detection industry to detect the presence of toxic hazards.

An electrochemical sensor is similar in design to a small battery, except that the chemical component required to produce the electric current is not present in the sensor cell.

As the target gas diffuses into the sensor’s membrane, it reacts with chemicals on the sensing electrode to produce an electrical current.

These detectors often detect toxic gases like carbon monoxide, hydrogen sulfide, and chlorine.

Common gases detected by Electrochemical sensors.

  • Carbon Monoxide (CO)
  • Hydrogen Sulfide (H2S)
  • Sulfur Dioxide (SO2)
  • Ammonia (NH3)
  • Chlorine (Cl2)
  • Nitrogen Dioxide (NO2)
  • Phosphine (PH3)
  • Formaldehyde (CH2O)
  • Hydrogen Cyanide (HCN)
  • Chlorine Dioxide (ClO2)
  • Ozone (O3)

Advantages of electrochemical sensors

It has a small size, low power consumption, good linearity and repeatability, a resolution generally reaching 0.1 ppm, and a long life.

Disadvantages of electrochemical sensors

Prone to interference, sensitivity is greatly affected by temperature changes.

Applications of electrochemical sensors

Electrochemical sensors can be applied in various fields, including environmental monitoring, biosensing, medical diagnosis, food safety testing, and industrial production.

Infrared Sensors (IR)

Infrared sensors commonly detect less reactive gases, which cannot be detected using typical electrochemical cells (such as CO2 or hydrocarbons).

Instead of relying on a chemical reaction, infrared sensors determine the amount of gas present by measuring how much light the specific gas absorbs.

Common gases that Infrared sensors can detect

  • Carbon dioxide
  • Flammable gas
  • Refrigerant gas
  • Exhaled alcohol

Advantages of Infrared sensors

  • Good selectivity only detects specific wavelength gases that can be customized according to the gas.
  • The optical detection method makes it less susceptible to the influence of harmful gases, preventing poisoning and aging; fast response speed and good stability;
  • Physical properties utilized, no chemical reaction, good explosion-proof properties.
  • High signal-to-noise ratio and strong anti-interference ability.
  • Long service life.
  • High measurement accuracy.

Disadvantages of Infrared sensors

  • Narrow measurement range
  • Vulnerable to dust and moisture
  • Cannot detect gas flow on-site
  • Higher cost

Applications of Infrared sensors

Infrared gas sensors are commonly used in industrial and commercial settings to detect and measure the levels of various gases.

They are essential in monitoring gas concentrations in hazardous environments, such as coal mines, oil refineries, and chemical processing plants.

Infrared gas sensors are also used in automotive and environmental applications, such as measuring vehicle exhaust emissions and determining air quality.

Additionally, they are used in medical equipment to monitor patients’ breath for the presence of certain gases.

Photoionization Detectors (PID)

The Photoionization Detectors (PID) detect volatile industrial compounds (VOCs) such as Benzene, which can be present during industrial spills.

PIDs rely on the specific chemical properties of the VOCs, but instead of absorbing light, they use a light source in the UV spectrum to ionize electrons off gas molecules.

PID detectors detect volatile organic compounds (VOCs) and other gases with ionization potentials below those of the air.

Advantages of Photoionization Detectors

  • High sensitivity
  • No poisoning problems.

Disadvantages of Photoionization Detectors

  • non-selective.
  • Greatly affected by humidity,
  • The short life of UV lamps, and
  • Expensive.
  • What is the most common gas sensor?

FAQ: 4 Common Types of Gas Sensors

What is the most common gas sensor?

Catalytic sensors are the most widely used devices for detecting combustible gases and vapors.

What is the difference between a gas sensor and a gas analyzer?

The simple distinction between the two devices is that a gas detector alerts a user when the level of a certain gas is too high in a confined space. In contrast, a gas analyzer provides accurate readings of the immediate atmosphere.

Do gas sensors detect CO2?

The most common principles for CO2 sensors are infrared gas sensors (NDIR).

Conclusion

These four gas sensor types, Infrared sensors and Photoionization Detectors (PID), are the most prevalent and widely used in the gas detection industry.

While numerous other gas sensors are available, these four stand out for their reliability and effectiveness in various applications.

 

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