In gas chromatography analysis, the hydrogen generator used for chromatography has become the preferred solution for laboratory replacement of high-pressure steel cylinders due to its ability to produce high-purity hydrogen gas (purity up to 99.999% or more) on site. However, as a flammable and explosive gas, the safety control of the generation and use process of hydrogen is crucial. Among them, the pressure relief valve and the flame arrester are like "double safety", respectively building a safety defense line from the dimensions of pressure loss control and flame backflow.
1、 Pressure relief valve: the "smart gatekeeper" of pressure
The core principle of a hydrogen generator for chromatography is to produce hydrogen gas through electrolysis of water or metal hydride reaction. If the gas production rate exceeds the gas demand during the process, or if the pipeline is blocked and the gas cannot be discharged in time, the internal pressure will rise sharply, which may cause container rupture or even explosion. At this point, the pressure relief valve takes on the responsibility of "releasing water".
Its working mechanism is based on mechanical balance: the valve body is equipped with an elastic diaphragm or spring-loaded valve core. During normal operation, when the system pressure is below the set threshold (usually 0.3-0.5MPa), the valve core tightly closes under the action of spring force, preventing gas leakage; When the pressure exceeds the threshold due to abnormal increase, the pushing force of gas on the diaphragm exceeds the resistance of the spring, and the valve core is pushed open, excess hydrogen gas is released to a safe area (such as a ventilation duct) through the pressure relief port, until the pressure drops back to the safe range, and the valve core automatically resets and closes. Some generators are also equipped with an "intelligent pressure relief" function, which can be linked to the control system to reduce gas production power and minimize pressure fluctuations from the root.
2、 Flame arrester: the "unidirectional insulator" of flames
Even with proper pressure control, localized combustion may still occur in hydrogen pipelines due to static electricity, friction from impurities, or external sources of ignition. If the flame propagates in the opposite direction along the pipeline to the inside of the generator (i.e. "tempering"), it may ignite unreacted raw materials (such as electrolyte during water electrolysis) or cause equipment explosion. The function of a flame arrester is to block this "flame backflow".
The core of its structure is a chamber filled with multiple layers of fine pore metal mesh (such as stainless steel corrugated mesh) or sintered ceramics. The pore size of these materials is much smaller than the combustion wavelength of hydrogen (the free radical chain reaction of hydrogen combustion requires a certain amount of space transfer). When the flame attempts to pass through the flame retardant layer, the heat will be quickly absorbed and dissipated. At the same time, the heat dissipation effect of the metal mesh lowers the flame temperature to below the hydrogen ignition point (about 570 ℃), interrupting the free radical chain reaction and extinguishing the flame. Experiments have shown that high-quality flame arresters can withstand thousands of tempering impacts without affecting the normal flow of hydrogen gas.