Market trends in refrigerant leakage detection

The Kigali Amendment to the Montreal Protocol, adopted in October 2016 and effective since January 2019, targets an 85% reduction in hydrofluorocarbon (HFC) production and consumption by 2045. This international agreement addresses the climate impact of HFCs through a phasedown approach. Many low-GWP (Global Warming Potential) refrigerants replacing HFCs are mildly flammable, requiring updated safety measures, including leak detection in certain applications. Standards such as UL 60335-2-40 and IEC-60079-29-1 outline these measures, and in the U.S., they will be incorporated into building codes for residential and commercial air-conditioning systems starting in 2025.

This article examines refrigerant classes used in the HVACR industry, trends in their adoption, and leak detection technologies supporting compliance with environmental and safety regulations.

Background on refrigerant transitions

The Montreal Protocol initially phased out ozone-depleting chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs), leading to the adoption of HFCs. Although HFCs addressed ozone concerns, their high GWP has driven global efforts, including the Kigali Amendment, to shift toward lower-GWP alternatives. This transition introduces challenges, particularly as many viable replacements exhibit flammability.

Classifying refrigerants

ASHRAE Standard 34 categorizes refrigerants based on toxicity and flammability, using a letter (A or B) to indicate toxicity and a number (1, 2, 2L, or 3) to denote flammability. Traditional refrigerants like CFCs, HCFCs, and early HFCs (e.g., dichlorodifluoromethane, A1) prioritized low flammability and toxicity. Newer low-GWP options such as hydrofluoroolefins (HFOs), hydrocarbons (e.g., propane), and A2L-class refrigerants tend to be more flammable. The A2L subclass, introduced recently, identifies refrigerants that are flammable but burn slowly.

Safety and low-GWP refrigerants

The shift to A2L refrigerants increases safety considerations due to their flammability. Standards like UL 60335-2-40 and IEC-60079-29-1 address these risks by recommending leak detection in HVACR systems. While not mandatory under the standards themselves, U.S. state building codes will require such systems by 2025, with regions like California accelerating adoption through agencies like the California Air Resources Board (CARB). This timeline challenges manufacturers to adapt quickly.

Common leak detection technologies

Several sensor technologies could be used for refrigerant leak detection, including Photoacoustic NDIR (PA), Non-Dispersive Infrared (NDIR), Thermal Conductivity (TC), Electrochemical (EC), and Metal Oxide (MOx):

PA sensors detect refrigerant gases by measuring acoustic waves generated from pressure changes caused by pulsed IR light absorption. They offer high sensitivity and selectivity, and are particularly well-suited for applications where precision and low cross-sensitivity are critical.
NDIR sensors use infrared absorption to detect refrigerant gases with high selectivity, though they are costlier and reach their limits with the extreme temperature and humidity requirements of the application.
TC sensors measure changes in thermal conductivity, offering fast response times and long-term stability, making them very suitable for high-volume A2L leakage applications.
EC sensors, while effective for some gases, lack the lifetime needed to meet A2L detection requirements, limiting their practicality.
MOx sensors are affordable and adaptable but are prone to drift over time and can degrade after exposure to high refrigerant concentrations, reducing reliability.

The choice of technology depends on factors like cost, durability, and compliance with standards like UL 60335-2-40.

Sensirion’s refrigerant detection technology choice

Sensirion has multiple gas sensor technologies available, which are suitable for refrigerant leak detection, including NDIR, TC, MOx, and others. After evaluating application needs, manufacturability, scalability, and compliance with UL 60335-2-40, Sensirion selected TC technology for A2L leak detection applications. This choice reflects TC’s stability and scalability, supported by Sensirion’s CMOSens® MEMS chip manufacturing platform.

Outlook for refrigerant detection

The rise of flammable low-GWP refrigerants in HVACR systems is inevitable as regulations tighten. As safety standards integrate into legislation, the demand for reliable detection solutions will grow, shaping technological development in the coming years. A2L is an important step towards lower GWP refrigerants, with Sensirion working on enabling other important refrigerants such as propane with reliable sensing.

Related sensors

SGD43S-M3-S7

New

Flexible and complete refrigerant leakage detection system for modern refrigeration systems

The SGD43S-M3-S7 is part of our SGD4x series of A2L refrigerant detection products, specifically designed for the HVACR industry as a complete refrigerant detection system (RDS). It is based on the thermal conductivity measurement principle and features a dual contact relay output that can trigger a signal relay to start a blower, switch off the load or warn a control board. Easy integration and installer-friendly feedback is enabled by a status-indicating LED for quick visual feedback.

With its fast response time and broad compatibility with A2L refrigerants thanks to its versatile multi-refrigerant calibration, it is an essential component for both residential and commercial HVACR systems. The SGD43S-M3-S7 ensures effective leak detection and complies with stringent industry standards, including UL 60335-2-40 and UL 60335-2-89. The single unit is triple calibrated for R-454A, R-454C and R-455A in refrigeration applications.

SGD43S-M3-S5

New

Flexible and complete refrigerant leakage detection system for modern HVAC systems

The SGD43S-M3-S5 is part of our SGD4x series of A2L refrigerant detection products, specifically designed for the HVACR industry as a complete refrigerant detection system (RDS). It is based on the thermal conductivity measurement principle and features a dual contact relay output that can trigger a signal relay to start a blower, switch off the load or warn a control board. Easy integration and installer-friendly feedback is enabled by a status-indicating LED for quick visual feedback.

With its fast response time and broad compatibility with A2L refrigerants thanks to its versatile multi-refrigerant calibration, it is an essential component for both residential and commercial HVACR systems. The SGD43S-M3-S5 ensures effective leak detection and complies with stringent industry standards, including UL 60335-2-40 and UL 60335-2-89. It offers dual calibration in a single device for R-454B and R-32 for HVAC applications.