Biochemical oxygen demand refers to the amount of dissolved oxygen consumed by microorganisms during the biochemical process of decomposing certain oxidizable substances, especially organic matter, in water samples cultured at 20 ℃± 1 ℃ for a set period of time. According to the national standard HJ 505-2009 5-day cultivation method, our company has designed and developed the SH series BOD analyzer, which can simulate the biodegradation process of organic matter in nature and measure the BOD value in water using the principle of mercury free pressure difference method. The whole machine is designed with full intelligence and manufactured using advanced research and development technology. The experimental process does not require the presence of experimental personnel, making it easy to operate and safe and reliable.