In refrigerant gas detection for fluorinated gases, including HFCs, HFOs, and A2L refrigerants, two primary sensor technologies—semiconductor sensors and infrared sensors—vie for prominence. Understanding the strengths and limitations of each is crucial for making informed decisions in both commercial and industrial settings. This is achieved by delving into a comparative analysis of semiconductor sensors and infrared sensors.

Semiconductor Sensors – How Do They Work?

Semiconductor sensors, also known as metal oxide sensors, are celebrated for their versatility and cost-effectiveness in detecting a wide range of gases, including refrigerants. These sensors operate by heating the surface of a silicon wafer coated with metallic oxides to temperatures ranging from 300 to 800ºF (149 to 426ºC). During normal operation, oxygen molecules adhere to the sensor’s surface, creating a resistance barrier. However, upon exposure to reducing gases like refrigerants, a redox reaction occurs, altering the resistance and increasing electrical conductivity.

Despite their versatility, semiconductor sensors lack selectivity and may produce false alarms in response to various gases – they will react to any reducing gas, not only refrigerants. Factors such as water vapor, high humidity, temperature fluctuations, and low oxygen levels can further impact their accuracy.

Infrared Sensors – How Do They Work?

Infrared sensors, on the other hand, have an operating principle based on the absorption of infrared radiation by target gases, including refrigerants like HFCs and HFOs. These sensors excel in precision and accuracy, operating by directing infrared light through a gas sample onto a detector element. The reduction in intensity of the infrared light source, attributed to the presence of the target gas, correlates directly with gas concentration. Infrared sensors boast immunity to cross-gas effects and environmental interferences, making them highly reliable in refrigerant applications. They offer excellent stability, resistance to poisoning, and minimal drift over time, ensuring long sensor lifetimes of typically around 10 years.

Comparative Analysis

Semiconductor sensor-based refrigerant gas detectors offer a cost-effective solution for a wide range of refrigerant gas detection applications and meet the neees of the majority of users. However, while semiconductor sensors offer cost-effectiveness and versatility, their lack of selectivity and susceptibility to false alarms can pose challenges in demanding commercial refrigeration and industrial refrigeration environments. In contrast, infrared sensors provide superior precision, accuracy, and immunity to environmental factors, making them ideal for critical applications where precise measurement is paramount and false alarms cannot be tolerated. Although infrared sensors may come with a higher price point, their exceptional performance in achieving lower minimum detectable levels compared to semiconductor sensors makes them an attractive choice for gas detection scenarios requiring heightened sensitivity and immunity to cross-sensitivity.

Conclusion:

In HFC, HFO, and A2L refrigerant gas detection, the choice between semiconductor sensors and infrared sensors ultimately hinges on the specific requirements and challenges of the application. While semiconductor sensors offer affordability and versatility, infrared sensors provide unmatched precision, reliability, and immunity to environmental factors. Understanding the distinct advantages and limitations of each technology is essential for ensuring accurate and reliable gas detection in commercial and industrial settings.