Pneumatic rotary spray gun mounted via manhole and used for cleaning oil storage tank

A pneumatic rotary spray gun mounted via a manhole and used for cleaning an oil storage tank relates to the technical field of oil storage tank cleaning equipment, and comprises a gearbox component and a gun body component connected with the gearbox component. The pneumatic rotary spray gun is characterized in that the gearbox component comprises a shell, a transmission system and a pneumatic system, the transmission system is arranged in the shell, the pneumatic system is connected with the transmission system, the gun body component comprises a gun tube, one end of the gun tube is connected with the transmission system, the other end of the gun tube is connected with a sprayer, and a water inlet flange and a mounting flange are further arranged on a body of the gun tube. Two motors are arranged, so that a large cleaning region covered by an annular cleaning track and a linear cleaning track can be formed and occupies about 2/3 of the area of the bottom of the oil storage tank, and after two spray guns are respectively mounted on two opposite manholes on side surfaces of the oil storage tank, the total bottom of the oil storage tank can be cleaned.