Background

Hydrogen is a highly combustible gas used in a wide range of industries. Despite its usefulness, it is a dangerous gas that can easily ignite and cause an explosion. Therefore, there is a need for efficient sensors that can detect hydrogen leaks and ensure workplace safety.

The importance of hydrogen sensor

Hydrogen detectors are critical to ensuring the safety of industries that use hydrogen. The gas is colorless, odorless and tasteless, making its presence difficult to detect. In addition, hydrogen has a lower explosive limit (LEL) of 4% and upper explosive limit (UEL) of 75%, meaning that even a small leak can cause an explosion if not detected early enough. Hydrogen sensors are therefore essential to detect any leaks and provide early warning signals to avoid accidents.

Types of hydrogen sensor

There are various types of hydrogen detectorrs, including electrochemical, thermal conductivity, solid state and optical sensors. The choice of sensor depends on the specific application and the desired sensitivity and accuracy.

Electrochemical sensor
Electrochemical sensor is the most commonly used hydrogen sensor. They work by measuring the electrochemical reactions that occur when hydrogen gas comes into contact with a sensing electrode. The current generated by the reaction is proportional to the concentration of hydrogen in the air. Electrochemical sensors are so sensitive and accurate that they can detect hydrogen concentrations as low as 10 parts per million (ppm).

Thermal conductivity sensor
The thermal conductivity sensor works by measuring the difference in thermal conductivity between hydrogen gas and the surrounding air. The sensor contains a heating wire wrapped in a hydrogen-sensitive material. When hydrogen comes into contact with the sensor, it cools the wire, which changes its resistance. The change in resistance is proportional to the concentration of hydrogen in the air. The thermal conductivity sensor is very sensitive and can detect hydrogen concentrations as low as 1% by volume.

Solid state sensor
Solid-state sensors are based on the principle of hydrogen adsorption and desorption by metal alloys. The sensor contains a thin film of a metal alloy that absorbs hydrogen when it comes into contact with a gas. The absorption of hydrogen changes the conductivity of the film, which is proportional to the concentration of hydrogen in the air. Solid-state sensors are very sensitive and can detect hydrogen concentrations as low as 10ppm.

Optical sensor
Optical sensors work by measuring the absorption or emission of light from hydrogen gas. The sensor contains a light source and a detector that measures the amount of light passing through the gas. When hydrogen gas comes into contact with the sensor, it absorbs or emits light, changing the intensity of the light detected by the detector. Optical sensors are highly sensitive and can detect hydrogen concentrations as low as 1ppm.

Working principle of hydrogen sensor

How a hydrogen sensor works depends on its type. An electrochemical sensor works by measuring the electrochemical reaction that occurs when hydrogen gas comes into contact with the sensing electrode. The electrodes contain a catalyst that promotes the oxidation of hydrogen, which creates an electric current proportional to the concentration of hydrogen in the air. The current is measured and converted into a signal that can be used to indicate the concentration of hydrogen in the air.