In the operation of a laboratory bench, the purity of nitrogen and hydrogen in the cylinder is generally required to be more than 99.999%, and that of ammonia is more than 99.99%. In order to ensure safety, all types of gas cylinders must be tested periodically for compression. Each test must be recorded in detail (such as inspection date, inspection conclusion, etc.) and loaded into the cylinder file. After inspection, gas cylinders that must be used or discarded after being decompressed are inspected by the inspection unit. In recent years, more and more air compressors and various gas generators have been used. The air compressor on the laboratory bench can collect the air in the surrounding environment, and after pressurization, purification and other processing, it can output pure air with a certain pressure. When using the FID, the air is a scavenger gas, the amount is large, and the air purity requirement is not very high, so the air compressor has a tendency to replace the gas cylinder in this respect. The common gas generators are N2 generator and H2 generator. These gas generators can produce the corresponding N2, H2, generally when the detector does not require high purity of the carrier gas. Note that the gas generators and air compressors on different types of laboratory benches produced by different manufacturers may be different. When purchasing, suitable instruments should be selected according to actual requirements.