Which factor makes a propeller type flow meter unsuitable for WWTP?

• A. Gas Bubbles
• B. The Debris in the Liquid
• C. Oil Slicks
• D. High Viscosity

Answer: (B)

Propeller-type flow meters rely on an unobstructed, freely rotating blade to sense flow. In wastewater from a WWTP, solids and debris can readily strike, wrap around, or lodge against the propeller and shaft, causing jamming, bearing wear, or complete seizure. That mechanical interference makes readings unreliable and drives frequent maintenance, which is why debris in the liquid is the factor that makes this meter unsuitable. Gas bubbles, oil slicks, or high viscosity can affect readings in other ways, but debris causing blockage and damage is the primary incompatibility in this context.