Hydrogen detector is used to monitor hydrogen gas levels in vehicles, fuel cells, storage tanks and other environments where flammable hydrogen gas may be present. Hydrogen is colorless, odorless and tasteless but is highly flammable at concentrations greater than 4% in air. It is also explosive when it comes into contact with chlorine, oxygen or other oxidizers. The hydrogen gas detection monitor detects the presence of this flammable, poisonous and toxic gas by monitoring its vapor in the atmosphere.

These hydrogen gas detectors usually have two principal components – the sensor and the alarm system. The sensor consists of a thick layer of some semiconductor material, typically made of semiconductor metal oxides (SnO2, In2O3) deposited on a glass or ceramic substrate and enhanced with catalytically active additives like noble metals and metal oxides (CoxOy) to accelerate the oxidation reaction that produces hydrogen. The sensor is surrounded by a matrix that carries the signal to the measurement system.

Detecting the Invisible: Hydrogen Detectors and Their Crucial Role in Safety

The sensors are normally calibrated at the factory to ensure accuracy and performance for the life of the device. They require regular bump testing to ensure that they perform correctly, especially in harsh environments where temperature and humidity extremes create sensor drift.

Recently, optical sensing technology, which is based on the use of optical fibers as carriers to sense and transmit light wave signals, has been developed to measure the concentration of hydrogen gas. These sensors are called evanescent wave type hydrogen sensor. Tabib Azar et al [86] reported the development of this new class of hydrogen sensor by using an optical fiber written with a Bragg grating structure. When the sensor is loaded with hydrogen, the Pd film inside the fabricated Bragg slot expands and induces a shift in the wavelength of the light passing through the grating. The sensor measures this shift in light intensity to calculate the concentration of hydrogen gas in the environment.