Hydrogen is highly flammable, and leakage poses a serious fire hazard. Therefore, it is crucial to detect hydrogen leaks early or even prevent them. Since hydrogen is invisible, odorless, and tasteless, this is not an easy task without specialized equipment.
Hydrogen is one of the lightest elements on Earth, so it quickly rises to the ceiling in a closed space and eventually fills the entire room. Even a spark of static electricity in the presence of hydrogen in the air is enough to cause an explosion. Therefore, it is important to detect hydrogen leaks immediately or, even better, prevent them.
Hydrogen leakage causes sound and vibration, so you can detect hydrogen leakage in various ways. We have compared three methods to explain how to detect hydrogen leakage quickly and safely.
Gas Sensors
Hydrogen can be detected with gas sensors, also known as ‘sniffers’, but this technique is not fail-safe. Gas sensors do not work well in oxygen-depleted environments and can even fail. Sensor malfunction is only detected when test gas is applied.
Gas sensors are also not specific. Although gas sensors often detect the presence of gas before an incident occurs, they only sound an alarm when there is a significant amount of gas in the space. This exposes maintenance workers to a high level of risk.
Gas sensors are almost always combined with other measurement methods, such as leak detection, body worn gas detection, and fixed gas detection. The disadvantage of this is that there are different data sources, so different solutions need to be purchased and maintained. For fixed detection, multiple detectors need to be installed, at least one per 40m3 or per 10 meters of wall.
Vibration Sensors
Hydrogen leaks and improperly functioning machines cause vibrations that can be measured with vibration sensors. Although these sensors work well in oxygen-depleted environments and are not affected by sensor poisoning, they do have several other disadvantages.
Vibration sensors have a limited frequency range in which they generate accurate measurement data. Depending on the sensor type, but especially the mounting method, the usable frequency range is often limited to 5 kHz. An incipient leak causes vibrations that lie in the higher frequency range (>20 kHz). Therefore, a vibration sensor only detects a leak at a later stage when the leak has already become larger and a significant amount of hydrogen has been lost.
Vibration sensors are wired, and multiple vibration sensors are needed in a room. Vibration sensors are specific to a floor or space, and a network of multiple sensors is needed for different measurement directions. This means that a lot of cabling must be installed to use this solution. Like gas sensors, when using vibration sensors, you know that hydrogen is leaking, but you do not know where the leakage is. Therefore, you will always need to conduct further investigation and take safety risks to find the cause and solve the problem.
Like gas sensors, when using vibration sensors, you know that hydrogen is leaking, but you do not know where the leakage is. Therefore, you will always need to conduct further investigation and take safety risks to find the cause and solve the problem.
Thermal Imaging Camera (OGI)
A thermal imaging camera is capable of detecting and visualizing gas leaks. The operating principle is based not so much on temperature differences but on differences in the absorption of infrared light by different gases. Therefore, this camera is also called an OGI (optical gas imager) to avoid confusion. The method allows gas leaks to be detected from tens of meters away.
The biggest drawback of this method is that it is unable to detect noble gases. Therefore, to detect hydrogen leaks, it is necessary to add a small amount (<5%) of detectable gas to the system. However, these added gases, such as SF6 or CO2, contribute to global warming and also add an extra cost in the industry.
Acoustic Camera
An acoustic camera, such as the Sorama CAM iV64Ex, has a series of 64 microphones that work together. These microphones use a wide frequency range to localize and quantify sound sources and sound pressure levels. An acoustic camera measures contactlessly at distances of 10 meters and sometimes even tens of meters.
Acoustic cameras can measure audible as well as ultrasonic sound. This is sound with a frequency of 20 kHz and higher, which is not audible to humans. Because the acoustic camera measures this high-frequency sound, it is possible to detect incipient problems early. Detection of hydrogen leakage is thus possible before vibrations or gas concentrations can be measured.
For operator surveillance, you can use a handheld acoustic camera, such as the Sorama CAM iV64Ex. When it is not feasible or desirable to have personnel walk rounds, you can opt for a fixed installation using the Sorama L642Ex or the use of an autonomous robot. A robot, combined with Sorama sensors, ensures that you are much more in control and that personnel are not exposed to unnecessary risks. This offers benefits in terms of safety, emissions, and uptime; a win-win-win situation.
Autonomous robots with visual and acoustic cameras are the eyes and ears in the factory, but also the nose as they can also be equipped with gas sensors (sniffers). Fixed surveillance rounds provide consistent measurements, and a robot is often equipped with multiple sensors. For example, both thermal and acoustic inspections can be carried out to see if there is a leakage.
The Future of Hydrogen Leak Detection
The use of Ex acoustic cameras in combination with autonomous robots will bring about significant changes in the way inspections are carried out in hazardous zones. Unwanted emissions are reduced, while costs are lowered, and above all, safety for maintenance and operating personnel is improved.
Unlike manual inspections or stationary sensors, the robotic acoustic camera provides complete coverage of the facility in a scalable, safe, and cost-effective manner. Robots can tirelessly detect gas leaks, freeing personnel from this complex and potentially dangerous task, allowing more time to be spent on actually solving the leaks. This progress represents a significant step towards safer, more efficient, and more sustainable industrial activities.
