This article was originally featured on H2Tech.
Hydrogen, more specifically Green Hydrogen, is being used increasingly across the globe for a wide range of industrial applications. In the US, forecasters predict that “hydrogen from low-carbon sources could supply roughly 14 percent of the country’s energy needs by 2050, including hard-to-electrify sectors now dependent on natural gas such as high-heat industrial processes and manufacturing fertilizer.” However, hydrogen is a potentially dangerous gas. A hydrogen leak in a refinery can rapidly escalate to a major disaster, and even in small amounts, exposure to hydrogen poses several different hazards to those working with it.
For decades, Catalytic Bead Sensors and Non-Dispersive Infrared (NDIR) Sensors have been staples in the gas detection industry and have increased the safety of dangerous working environments. However, neither of these technologies are effective for use in environments where hydrogen is present. If Pellistor/Catalytic Bead sensors are calibrated to hydrogen, detection readings are not accurate, delivering a reading of +/- 30% of actual concentration. NDIR sensors cannot detect hydrogen because it does not absorb infrared light.
The Evolution of Gas Sensing Technology
Until recently, the gas detection industry has been relatively stagnant for nearly four decades. It was dominated by the use of Pellistor/Catalytic Bead and NDIR sensors. Pellistor/Catalytic Bead sensors were introduced nearly a century ago and still operate using the same principles found in their initial design. They measure the temperature difference between two beads – one inert and one coated in a chemical catalyst. The bead coated with the catalyst will heat more than the inert bead in the presence of many flammable gases.
Pellistor/Catalytic Bead sensors are appealing because they respond to a full range of flammable gases, including hydrogen, methane, butane, propane, and carbon monoxide. They are also relatively low-cost. Unfortunately, though, these sensors have critical limitations. When calibrated to a single gas, they provide inaccurate readings for all other gases. They must also be calibrated frequently to perform properly, consume relatively high power, and do not function in low-oxygen environments. However, their most significant deficiency is that they tend to become ‘poisoned’ when exposed to high concentrations of flammable and combustible gases, or when exposed to even low concentrations of common chemicals like silicones present in many cosmetics and car waxes. When this occurs, the sensors do not work correctly, or at all, even though they may appear to be functioning normally. This is a scenario that can put the user in a hazardous situation where they are unaware of dangerous or toxic gases present in the environment. Read More