On June 26, 2018, convened by the Quality Testing Center of a certain petrochemical company, the Beijing Bianhua Electric Instrument Exchange and Learning Class was held at the company's quality inspection center. The attendees were the laboratory directors and technical personnel of each petrochemical plant, and the speaker was Mr. Bian Dongfu, an expert in water quality analysis instruments (President of Beijing Bianhua Electrochemical Analysis Instrument Co., Ltd.).