(1) Breathing width should be installed at the highest point in the gas space of the tank to reduce material evaporation losses and to provide the most direct and maximum access to the breathing valve smoothly. Usually for vertical tank, the breathing valve should be installed in the top of the tank roof as far as possible, for the tank roof to be insulated tank, can be installed in the vicinity of the ladder platform; (2) When the need to install two breathing valves, (3) If the respiration valve is used on a nitrogen sealed can, the nitrogen gas supply pipe should be taken away from the breathing valve port and inserted into the tank by the top of the can about 200mm, so that the nitrogen into the tank After the direct discharge, to achieve the purpose of nitrogen seal.