Making sense of refrigerant leaks

Refrigerant leaks in HVAC systems are a quiet yet costly threat to both the environment and operational budgets. As global regulatory bodies implement stringent standards, building owners face increased pressure to accurately detect refrigerant leaks. Refrigerant leak sensors have, thus, become vital components, but selecting the appropriate sensor technology and ensuring proper maintenance pose considerable challenges.

Michael Ahrendt, Assistant Manager: Sales and Marketing, Figaro USA, identifies regulatory compliance as one of the primary challenges facing building owners today. “With things changing in 2025, especially with the mandatory use of A2L refrigerants, building owners must adapt significantly more than they previously did,” he notes, highlighting the complexities introduced by shifting regulatory landscapes.

Achieving accurate detection

Accurate leak detection hinges largely on the choice of sensor technology and proper sensor positioning. Zachary Ziegler, Global Product Line Manager, MSA Safety, emphasises the importance of precise installation and regular maintenance: “Common issues arise when systems are improperly installed, inadequately commissioned or irregularly calibrated. Ensuring sensors are positioned correctly, especially considering airflow patterns, is crucial for accurate leak detection.”

Ziegler says it leverages aspirated systems, particularly the Chillgard 5000, to significantly enhance detection capabilities. “Our aspirated systems are capable of detecting refrigerant leaks down to one part per million, providing early detection before minor leaks become major problems,” Ziegler explains. This contrasts with diffusion-type sensors, which typically detect leaks only at higher concentrations, potentially missing smaller leaks, he adds.

Sensor calibration frequency is another critical factor. Ziegler says MSA’s aspirated systems generally require annual calibration, although frequency may vary depending on environmental factors. “Ambient conditions don’t usually affect sensor operation directly, but high particulate or moisture levels might necessitate more frequent end-of-line filter replacements,” Ziegler adds.

Ahrendt outlines how Figaro’s metal oxide semiconductor (MOS) sensors detect leaks through a chemical reaction. “There’s a slight delay in detection, caused partly by the chemical reaction itself and partly by the time it takes for refrigerant concentrations to build up to the sensor’s detection threshold,” Ahrendt clarifies. Despite this minor latency, MOS sensors offer a highly cost-effective solution, with reasonable sensitivity and response times compared to more expensive alternatives, Ahrendt says.

Technology advancements and long-term stability

Technological advancements continue to refine sensor capabilities, particularly concerning response times and interference minimisation. Ahrendt says Figaro has been enhancing its MOS sensor technology by improving internal sensing elements and filters, specifically designed to reduce interference from other gases commonly found in HVAC environments. “Our proprietary filter technology significantly reduces cross-sensitivity,” Ahrendt says, reinforcing the reliability of Figaro’s sensors.

Posifa Technologies offers an alternative technology based on thermal conductivity (TC), which the company says significantly extends sensor lifespan. Peng Tu, Co-founder and CEO, Posifa Technologies, describes how TC sensors provide substantial advantages in long-term stability. “Thermal conductivity-based sensors have lifespans rated between 15 and 20 years, significantly surpassing optical-based NDIR sensors, which typically last 5-10 years,” Tu notes. “The simpler, semiconductor-based design of TC sensors makes them more robust and less prone to operational failures.”

Tu underscores the practical benefits for building owners: “Long-term stability means fewer replacements, reducing both operational worries and long-term costs. This makes TC sensors highly attractive from an economic standpoint, especially for applications where low maintenance and longevity are paramount.”

Addressing cross-sensitivity and environmental adaptability

Cross-sensitivity remains a critical concern, particularly in environments with diverse gas profiles. MSA Safety says it addresses this through rigorous cross-sensitivity testing. “Our infrared sensors undergo comprehensive calibration and testing to ensure minimal interference from other gases commonly present in HVAC environments,” Ziegler says.

Adaptability to varying environmental conditions is also essential. Ziegler elaborates that sensor placement is pivotal in maintaining accurate detection in varying humidity and temperature levels. Ziegler advises that sensors should be strategically positioned in areas most prone to leaks, such as condensers and evaporators, to ensure reliable performance regardless of ambient conditions.

Figaro says its sensors meet stringent UL 60335-2-40 standards, enabling robust performance across diverse conditions. “Our modules are compounded to resist condensation and liquid ingress, ensuring consistent reliability,” Ahrendt says.

Preparing for the A2L regime

As the industry shifts towards using environmentally friendly A2L refrigerants, sensor compatibility has become crucial. All three companies affirm their preparedness for the transition. Ahrendt says Figaro’s MOS sensors – specifically developed for A2L refrigerants, such as R-454B – illustrate the industry’s proactive response. Likewise, MSA Safety’s infrared-based sensors already effectively detect these emerging refrigerants, Ziegler points out.

According to Posifa Technologies, its TC sensors offer a distinct advantage in addressing new refrigerants. “Our technology inherently adapts easily to new refrigerant compositions without significant recalibration or redesign,” Tu notes, demonstrating the company’s readiness for evolving market requirements.

Conclusion

Refrigerant leak detection sensors are indispensable tools in safeguarding HVAC operations, environmental compliance and economic viability. Selecting suitable sensor technology, ensuring precise installation and adhering to regular maintenance schedules significantly reduce the risks associated with refrigerant leaks. Representatives from Figaro USA, MSA Safety, and Posifa Technologies underline the importance of technological advancement, regulatory compliance and sensor durability as key factors in addressing refrigerant leak challenges effectively.

As sensor technologies evolve, building owners and facility managers can expect enhanced operational reliability and cost-efficiency, ensuring they remain compliant with current and future regulatory landscapes.