A self-priming pump is a type of fluid pump that needs to be filled with liquid within the pump cavity or pump body to start the pumping process. This design feature provides an opportunity for the pump to better handle air pockets or accumulations of air bubbles in the pumps operating mechanism that can impair its proper operation. Self-priming pumps can be automatically self-priming, meaning they feature close tolerance working parts that trap fluids in the pumps body, preventing them from returning from the discharge side of the pump to the suction side when the pump is not in operation. Self-priming centrifugal pumps overcome air binding by initially mixing any residual air in the pumps working mechanism with fluid during the priming process. This blending allows the resulting mix to move readily through the pumps body on initial start-up, removing the air and aiding product flow on the suction side of the pump. The "self-priming" capability of this type of centrifugal pump comes from the ability of the reservoir to retain liquid after its very first prime. Self-priming pumps are used in various industrial and commercial facilities, from steel mills, power plants, and sewage treatment facilities to wineries, breweries, and more.