Hydrogen (H2) is a colorless, odorless, odorless, and non-toxic gas. It is only 0.089 grams per liter under standard conditions, which is only 1 / 14.5 of air. It's the lightest gas. It has the smallest viscosity, the highest thermal conductivity, and strong chemical activity, permeability and diffusivity (the diffusion coefficient is 0.63 cm 2 / sec, about 3 times that of methane), so it is prone to leakage in the production, storage and use of hydrogen. Hydrogen is also a strong reducing agent, which can react with many substances to varying degrees to produce various types of hydrides. Hydrogen has a very wide range of uses. Because hydrogen has a strong permeability, when steel is exposed to hydrogen at a certain temperature and pressure, the atomic hydrogen dissolved in the crystal lattice of the steel causes embrittlement in the slow deformation. It reacts with carbon in the microscopic pores of steel to generate methane. As the amount of methane generated increases, the pores expand into cracks, which accelerates the migration of carbon in the microstructure, reduces the mechanical properties of the steel, and even causes material damage. Usually under high temperature, high pressure or liquid nitrogen temperature, it is easy to cause hydrogen embrittlement or hydrogen corrosion. Therefore, equipment and pipelines working in an environment with hydrogen can cause leakage of hydrogen due to corrosion and cracks. The permeability of hydrogen is also manifested in that if a hydrogen gas is contained in a rubber bag, the hydrogen can leak through the rubber bag. Therefore, a container using a rubber pad as a sealing member also easily generates hydrogen leakage.
At the place of use of hydrogen and the storage and transportation of hydrogen, we should also pay great attention to the issue of fire protection and explosion prevention, and to prevent the existence and generation of any ignition source. Eliminate the conditions that cause it to burn and explode. Many uses of hydrogen are carried out under humidification and pressurization, and the ignition energy and tower explosion limit of hydrogen vary with temperature and pressure. In general, as pressure increases and temperature increases, the explosion limit range becomes wider, which is more likely to cause an explosion fire. In addition, hydrogen has strong permeability and diffusivity, and it is easy to cause leakage and equipment corrosion and damage. Therefore, in any place where hydrogen is used, whether it is in the production process, or when cleaning and repairing the equipment using hydrogen, it is necessary to pay great attention to using explosion-proof tools to prevent impact (collision) and friction sparks Explosion accident.
The above is the introduction of the matters needing attention in the selection of explosion-proof tools in a hydrogen environment. I hope it will be helpful to you. If you have other questions and you want to consult, you can contact us.