What is the difference between auto-prime and self-priming dewatering pumps?

Auto-prime pumps (Cosmos CAP range) and self-priming pumps (Cosmos CSP range) both operate above the waterline but differ in performance and design. Auto-prime pumps feature a dedicated priming chamber that automatically evacuates air before each start, enabling suction lifts up to 9.8 metres and the ability to run dry without damage — critical for intermittent dewatering applications where sumps empty unpredictably. The CAP range delivers flows up to 74,483 LPM at heads up to 169 metres, powered by diesel engines (KOEL, Eicher, Baudouin, CAT), making them ideal for remote sites without electricity, large flood-control deployments, and mining applications. Self-priming pumps like the CSP prime manually on first use and require electricity, delivering up to 4,500 LPM at 28 metres head — well-suited for smaller construction sites, basement dewatering, and foundation drainage where power is available and the installation is fixed. Choose auto-prime when power is unavailable, portability matters, or the pump runs intermittently. Choose self-priming when electricity is available, flow requirements are moderate, and the installation is fixed. Suction lift is up to 9.8 metres for both.