Understanding EN 14624 and calibration requirements in Europe

The evolution of leak detection and standards

We live in an era of rapid and continuous improvement, driven largely by advancements in technology and tools. In the refrigerant leak detection industry, progress has been especially impressive.  Not long ago, the only practical way to detect refrigerant leaks was with a halide torch—an open flame that changed color when it burned chlorine-based refrigerants like R22. Since then, electronic sensor technology has advanced through key stages: Corona Suppression, Surface Reaction (EMOS or CMOS), Heated Diode, and Infrared absorption.

These innovations have been driven by the need to detect a wider variety of refrigerants at smaller leak rates. Today, the industry’s gold standard is 5 grams per year (5 g/year). Thanks to rapid advancements in sensor technology, modern leak detectors are now capable of identifying incredibly small leaks that were once undetectable.

Now imagine a refrigerant leak detector so sensitive that it can detect a leak of just 0.000000158 grams per second—or 1.58 × 10^-7 grams per second. You’d probably expect a tool this precise to need regular calibration and testing to ensure it’s working properly, right? It may surprise you to learn that 1.58 × 10^-7 grams per second is exactly the same as a 5 g/year leak.

Once you see how tiny that rate really is, it becomes clear why even the most experienced technicians can sometimes miss a small leak—and why it’s critical to choose the right detection technology and regularly verify that your leak detector can reliably sense at least this level.

Where does the 5 g/year recommendation come from?

According to the EN 14624:2020 European standard, 5 g/year is the minimum sensitivity required for electronic refrigerant leak detectors used to service HVAC/R systems. Every detector must be able to reliably detect leaks of at least 5 g/a (grams per year) of R134a — a performance benchmark designed to catch even the smallest leaks before they waste refrigerant, reduce system efficiency, harm the environment, or violate F-Gas regulations.

While the standard sets this high bar for sensitivity, it does not impose a universal, legally mandated annual calibration schedule for every device in every country. In fact, the only place with a strict legal obligation to regularly test these detectors is France. For everywhere else, regular verification is a strong professional recommendation — but one that’s critically important if you want to do your job to the highest standard and protect both your customers and the planet.

Even without laws or potential fines, a leak detector that can’t reliably find a 5 g/a leak is like a smoke detector with dead batteries: it may give you a good feeling to have it, but it fails you when it really counts. That’s why experts strongly recommend testing your detector on a reference leak source at least once per year (and more often in heavy-use environments).

The good news? How often — and how — you actually need to verify performance depends heavily on the sensor technology inside your tool.

Chemical/heated diode sensors and sensitivity degradation

In contrast, detectors that rely on heated diode or surface reaction sensors react chemically with refrigerant. Over time that reaction causes the sensor to lose sensitivity, weaken its response, and potentially miss small leaks. These tools often require more frequent sensor testing (self testing or calibration/repair house) and sensor replacement to stay compliant with EN 14624 performance expectations. Just because you found a leak yesterday with this type of leak detector, does not guarantee it will work the same today.