Measuring sludge flow: which device is generally not used for sludge flow rate measurement?

Introduction / Context:
Sludge streams can be viscous, non-Newtonian, and contain suspended solids. Flow devices must tolerate solids, reduce clogging risk, and remain accurate at low Reynolds numbers. Open channel primary elements (weirs, flumes) are common, whereas devices designed for clean, high-speed fluids are unsuitable.

Given Data / Assumptions:

• “Sludge” implies solids-laden, often slow-moving flow.
• Measurement can occur in open channels (weirs/flumes) or in pipes with suitable elements.
• Kennison nozzle is a nozzle-type DP element used mainly for clean, high-velocity fluids (often gases/steam).

Concept / Approach:
Devices with narrow throats and high susceptibility to fouling are poor choices. Weirs and Parshall flumes handle solids better and are widely used in wastewater and sludge handling. Orifice plates can be used but may clog and are generally less favoured unless solids are minimal and maintenance is frequent. Kennison nozzles are particularly unsuited to sludge because they are intended for clean service and can foul quickly.

Step-by-Step Solution:

Verification / Alternative check:
Wastewater practice standards specify weirs and flumes for sludge/effluent; nozzle DP elements are for clean, high-Re service.

Why Other Options Are Wrong:

Common Pitfalls:
Assuming all DP elements are interchangeable; sludge demands solids-tolerant primary devices.

Final Answer:
Kennison nozzle