Butterfly valve for transformers: It is installed at the flange connection between oil tank (or pipeline) of oil-immersed transformer products and detachable assembly parts. It is used to open or block the transformer oil circuit, and also can be used as butterfly valve for emergency oil discharge or maintenance oil discharge. Butterfly valves are usually installed between the oil tank and radiator fin of an oil-immersed transformer to control the oil flow between the transformer tank and radiator fin. When large power transformers leave the factory, radiators are usually individually packaged to reduce the transport size. At this point, the butterfly valve is closed to prevent external air or water from entering the transformer tank. After the transformer is transported to the installation site, install the radiator on the butterfly valve one by one. When the radiator is installed, the butterfly valve can be opened to allow the oil flow between the transformer tank and the radiator to flow, thus providing heat dissipation.