Auto-prime pumps and self-priming pumps both operate above the waterline — but they work differently and suit different site conditions.
Auto-prime pumps (Cosmos CAP range) use a dedicated priming chamber that automatically evacuates air before each start. This means the pump can run dry without damage — critical on intermittent dewatering jobs where sumps empty unpredictably. The CAP delivers flows up to 74,483 LPM at heads up to 169 metres, powered by diesel engines (KOEL, Eicher, Baudouin, or CAT). That makes it the right choice for remote sites without electricity, large flood-control deployments, and mining applications where the pump will move sites repeatedly.
Self-priming pumps (Cosmos CSP range) prime manually on first use and require electricity. They deliver 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.
Quick rule of thumb:
- Choose auto-prime when power is unavailable, portability matters, or the pump will run intermittently
- Choose self-priming when electricity is available, flow requirements are moderate, and the installation is fixed
Suction lift is the same for both: up to 9.8 metres from water surface to pump inlet.