Pumping equipment selection: Which pump type is commonly termed a non-clog pump because it permits passage of solids present in raw sewage?

Introduction / Context:

Sewage contains rags, grit, and fibrous materials. Pumps in lift stations must pass such solids without frequent blockage. Special impeller designs and pump selections address this practical need.

Given Data / Assumptions:

• Raw municipal sewage with suspended solids and fibrous matter.
• Goal: select a pump that can handle solids passage.

Concept / Approach:

Centrifugal sewage pumps with non-clog impellers (e.g., single-vane, two-vane, recessed/vortex impellers) are widely used. They provide sufficient passage diameter and hydraulic design to reduce ragging and clogging. Reciprocating pumps are unsuitable for debris-laden flows, and pneumatic ejectors are niche devices, not mainstream pumps.

Step-by-Step Solution:

Verification / Alternative check:

Manufacturers market “non-clog” centrifugal pumps specifically for wastewater service, corroborating the choice.

Why Other Options Are Wrong:

• Reciprocating pump: Sensitive to solids; maintenance-intensive.
• Pneumatic ejector: Uses compressed air; limited capacity and not a general-purpose pump.
• Axial-flow only: Used for high flow/low head clean water; not the standard solids-handling sewage pump.

Common Pitfalls:

• Ignoring solids passage diameter when selecting pumps.
• Overlooking ragging tendency and need for chopper/vortex options.

Final Answer:

Centrifugal pump (non-clog impeller)