Red Lion 71 GPM 1-1/2 HP Self-Priming Cast Iron Sprinkler Pump. This cast iron pump is designed for years of service and reliability. Sprinkler pumps are designed for proper lawn and garden saturation when you have an alternative water source. This 1-1/2HP model is self priming, which means you only need to prime it once! This means less time to get going after the initial set up.