Water Pumps

Open, Semi-Open and Closed Impellers

Impellers are often classified first by how their vanes are supported or enclosed. This construction influences efficiency, pressure capability, solids passage, clog resistance, wear, and maintenance.

Guide comparing open, semi-open, and closed impeller construction, with examples of specialized and non-clogging designs in each group.
Visual guide: compare the shrouds around the vanes, then use the quick cards below. Select the image to enlarge it.

Quick comparison

Choose by Construction

Construction changes how the impeller balances efficiency, pressure and solids handling.

Swipe the cards to compare

01

Open

Vanes are exposed without a front shroud, making the passages easier to inspect and clean.

Best for
Fibrous, viscous or solids-laden liquids where clog resistance matters.
Examples
Vortex, channel, grinder and two- or three-vane designs.
02

Semi-Open

One shroud supports the vanes while the opposite side remains open.

Best for
Wastewater, light slurry and process liquids with small to medium soft solids.
Examples
Semi-open vortex, channel, recessed, multi-vane and high-solids designs.
03

Closed

Front and back shrouds enclose the vane passages for controlled flow and high efficiency.

Best for
Clean-water boosting, HVAC circulation, boiler feed and multistage service.
Examples
Standard multi-vane, two-vane closed, high-solids closed and inducer-assisted designs.