Propeller meters use multiple blades made of rubber, plastic, or metal. The propeller rotates on a horizontal axle geared to a totalizer that displays total volume that has passed the meter. The propellers are sometimes hung from a sealing plate with a gasket to seal around a saddle opening on the top of the pipeline. Others have propellers supported by spiders in short, permanent tubes for connection into pipeline flow.
Some meters also display instantaneous discharge rate with indicator hands on dials.
The meters are available for a range of pipe diameters from 2 to 72 in. Small changes of frictional resistance of bearings and other mechanical parts caused by wear can cause large deviations from calibration, especially at the low discharge end of measurement range. Propeller meters should be selected to operate near the middle of their design discharge range. This equipment can be a problem in existing irrigation systems with oversized pipes relative to delivery needs. Sections of the oversized pipe may need to be replaced with smaller pipes to provide enough velocity and approach pipeline length to allow development of velocity profiles.