Because the spherical throttle check valve is simple in construction and has no mechanical parts, both horizontal and vertical installations are suitable. Its working principle is through the free movement of the valve ball in the valve body, even if the fluid in the pump contains solid suspended matter, there is no risk of clogging. When the pump is running, the ball throttle valve is adjusted as needed, turning to the liquid flow side, leaving enough free flow of liquid to reduce load loss. In order to ensure good sealing performance and no noise during operation, the ball is coated with nitrile rubber to prevent fresh water, sea water, wastewater or rain, and corrosion of residual hydrocarbon liquids.