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Checking for refrigerant leaks in air conditioning and refrigeration systems is a regular part of a service technician’s job. And it’s an important one, as refrigerant leaks not only represent a financial and operational burden to end users, they’re not great for the environment either.

Fortunately, there are numerous ways to check for leaks, including everything from soap bubbles to fluorescent dyes to feature-laden handheld electronic detectors that can be used with a wide variety of refrigerants. There are arguments to be made for each method, but for technicians trying to decide which handheld model to purchase, there are some important factors to consider.

Current Technology

There are many different types of electronic leak detector technologies that can be used to pinpoint system leaks, and each technology offers different benefits. Heated diode, heated electrolyte, infrared (IR), metal-oxide semiconductor (MOS), and ultrasonic are among the most common electronic leak detectors used for HVACR service applications, said Matt Lindorfer, technical product manager with Ritchie Engineering Co. Inc. – Yellow Jacket Products Division.

“Heated diode and heated electrolyte leak detectors heat the refrigerant to the point that the gas molecules are broken apart for analysis,” he said. “Since they rely on the presence of these specific molecules, heated diode leak detectors are more sensitive to some refrigerants than others. The heated electrolyte sensor technology works in a similar manner to heated diode sensors but uses less heat, which gives the sensor longer life. These technologies are typically the lowest in cost when compared to other leak detector technologies, making this technology the most popular in the market.”

IR leak detectors are a newer technology that utilize a beam of infrared light to analyze the type of refrigerant gas present. According to Lindorfer, this technology has good sensitivity and accuracy across all refrigerant types since it does not rely on specific molecules. These detectors are also less susceptible to false-positive alarms and triggers due to other gases in a given environment since light absorption in the IR spectrum is very gas-specific. He noted that these leak detectors are typically higher in cost when compared to heated diode/electrolyte equivalents, but they are gaining popularity due to their increased sensitivity to newer refrigerants and longer sensor life.

When comparing heated diode and IR leak detectors, the important differences to keep in mind between the two types of technology are sensor life, sensor degradation, and triggers on false positives, said Tony Gonzalez, technical training manager at Fieldpiece.

“When it comes to sensor life, the IR detector has approximately 10 years, while the heated diode leak detector has approximately 300 hours,” he said. “The IR leak detector also maintains high sensitivity throughout the life of the sensor, while the heated diode leak detector’s sensitivity degrades over time. Lastly, IR models minimize false positives on soap bubbles and oils, while the heated diode models are more prone to trigger false positives.”

Another type of technology is the MOS leak detector, which utilizes oxidation/reduction reactions on a metallic oxide substrate to detect present gases. MOS sensors are sensitive to many chemicals and gases other than the target refrigerant, often resulting in false-positive alarms if leak detection is taking place in the presence of these other chemicals, said Lindorfer. Generally, they are also less sensitive to smaller leaks than heated diode/electrolyte and IR technologies, so small leaks can go unnoticed.

Finally, there are ultrasonic leak detectors that sense the noise created when a gas is leaking from a pressurized vessel, which cannot be heard by the human ear. According to Lindorfer, these detectors work well across all refrigerants, and they are less susceptible to false-positive alarms since they utilize sound waves instead of the gas composition. However, as with the MOS leak detectors, their sensitivity is limited, and they may not detect smaller leaks that can be found with heated diode/electrolyte and IR leak detectors.

How to Choose

For most technicians, the decision comes down to purchasing either a heated diode or an IR leak detector. Gonzalez believes that even though an IR leak detector may have a higher upfront cost, it more than pays for itself because the sensor does not need to be replaced.

“Plus, the IR sensor maintains its high sensitivity throughout its lifespan and minimizes false triggers to soap bubbles and oils,” he said. “All these factors ensure technicians pinpoint the exact location of leaks in the field, saving them time and hassle.”

STATE OF THE ART: Fieldpiece’s DR82 IR leak detector features a state-of-the-art infrared sensor that detects all HFCs, CFCs, HCFCs, HFOs, and blends. (Courtesy of Fieldpiece)

Fieldpiece offers both an IR leak detector (DR82) and a heated diode leak detector (DR58). Both models help to pinpoint the exact locations of a leak with a numerical leak size indicator, increasing bar graph, and audible and visual alerts, said Gonzalez.

Yellow jacket also offers both heated electrolyte and IR leak detectors for conventional refrigerants. Their newest leak detector is the Accuprobe™ IR, which utilizes IR technology for good sensitivity to all CFC, HCFC, HFC, and HFO refrigerants, said Lindorfer.

“It is important to note that many of the newer HFC and HFO refrigerants are comprised of fewer chlorine and fluorine atoms, which the heated diode/electrolyte technology relies on for leak detection,” he said. “That is why IR technology offers the best overall sensitivity and accuracy across all refrigerant types.”

Some of these newer refrigerants, such as R-32 and R-454B, are also classified as being mildly flammable (A2L), so technicians should always check with the manufacturer to make sure that the leak detector they purchase (or currently own) can be used with them. As for A3 refrigerants such as R-290, these are highly flammable and require the use of a combustible leak detector that is certified for use with those types of refrigerants.

When it comes to deciding which leak detector to purchase, technicians should do their research and select a leak detector brand and technology that is considered to be of good quality. In addition, they should consider not only the types of refrigerants they’re currently using, but the refrigerants that will be in the field in just a few years.

“We are in the midst of another widescale refrigerant transition as traditional HFCs are being phased down and lower-GWP alternatives are being introduced around the world,” said Lindorfer. “This should guide technicians in determining which leak detector makes the most sense for their line of work. Technicians also rely on their leak detectors to perform well for many years to come, so quality counts. While high-quality leak detectors can be a bigger investment up front, they typically have a longer life and require less maintenance, making them a better financial option in the long run.”