What Should Be Noted in the Verification of Combustible Gas Detectors and Toxic Gas Detectors?
Everyone knows that a gas detector is an instrument that detects gas concentration. Suitable for hazardous areas with combustible or toxic gases, capable of continuously detecting the lower explosive limit of the tested gas in the air for a long time. In the process of verifying combustible gas detectors, it is inevitable to use flammable and explosive gas standard substances. Therefore, in this work, explosion prevention is more important than the verification work itself. The three elements of gas explosion are explosive substances, ignition sources, and auxiliary gases. Explosive substances include substances that can react with oxygen (air), including gases, liquids, and solids. Gases: hydrogen, acetylene, methane, etc; Liquids: alcohol, gasoline; Solid: dust, fiber dust, etc.
In the process of verifying toxic gas detectors, in order to prevent occupational hazards to personnel during work, it is first necessary to pay attention to personnel protection and use high-efficiency exhaust facilities. If conditions permit, all detection equipment should be installed in the exhaust system and an airflow balance port should be set up to facilitate the rapid diffusion of harmful gases outdoors or into the exhaust gas treatment system. If an automated detection system can be used, personnel can control the on/off of gas with a computer, which is a great protection for personnel.
In all calibration work using toxic and harmful gas standard substances, it is recommended that calibration personnel wear portable gas alarms to ensure their own safety.
Toxic and harmful gases have different characteristics, some have adsorption properties, while others are highly soluble in water. In order to avoid affecting the accuracy of measurement values when standard gases pass through, stainless steel pipes should be selected as much as possible, kept dry, reduced pipeline length, and ensured gas flow rate and pressure. Meanwhile, due to the varying densities of each gas relative to air, different exhaust methods are required.
Different gases: Hydrogen sulfide is a colorless gas with irritant and suffocating properties, and is corrosive to metal materials. Hydrogen embrittlement often causes instrument explosion and accelerates the aging of non-metallic materials. Therefore, metal pipelines must be avoided in the gas pipeline of the hydrogen sulfide detector, and polytetrafluoroethylene pipelines must be used instead.
Polytetrafluoroethylene is widely used in the detection of gas detectors due to its excellent chemical stability, corrosion resistance, sealing, high lubrication, non viscosity, electrical insulation and good anti-aging endurance. However, due to the hardness of polytetrafluoroethylene tubes, latex tubes are required for connecting different gas paths. When connecting, latex tubes are used as auxiliary connections outside the polytetrafluoroethylene tubes to avoid contact with gases and prevent corrosion and aging. The density of hydrogen sulfide gas is 1.19 times that of air, slightly heavier than air, so it is advisable to use exhaust air.
