Cyz-a self-priming centrifugal pump, it is of simple structure, convenient operation, smooth operation, maintenance easy, high efficiency, long service life, with strong self absorption capacity, and other advantages. At the end of the valve is not needed in the pipeline, just before work to ensure the pump body certain priming oil. The pump is suitable for marine oil pump, bilge pump, fire pump and ballast pump machine cooling water cycle, etc.. Transporting gasoline, kerosene, diesel oil, aviation kerosene and other petroleum products and sea water, water respectively, medium temperature -20-80 degree and sealed with hard alloy mechanical seal, such as conveying liquid chemical can be converted to resistance to corrosive mechanical seal.