The DH-20 circulating constant temperature oil tank adopts a microcomputer intelligent control system. There is a circulating pump that can draw out the constant temperature liquid in the tank and establish a second constant temperature field. Widely used in research departments such as petroleum, chemical, electronic instruments, physics, chemistry, bioengineering, medicine and health, life sciences, light industry and food, physical property testing, and chemical analysis, as well as in higher education institutions, enterprise quality inspection, and production departments, providing users with a controlled cold and hot liquid environment with uniform and constant temperature during work. Fluctuations of ± 0.05 ℃ and ± 0.1 ℃ can be selected. LED dual window traffic light dual color digital display, also available with large frequency screen LCD display, touch soft key for quick temperature setting, easy to operate. The microcomputer corrects the deviation of temperature measurement values, and the temperature digital display accuracy can be selected as 0.1 ℃ or 0.01 ℃. Equipped with an over temperature alarm system.