1. Technical Complexity: Unlike simple mechanical flow meters, ultrasonic meters rely on complex electronic circuitry to generate, receive, and process high-frequency sound waves. This involves precision timing and digital signal processing (DSP) to account for transit-time differences or Doppler shifts. This complexity requires specialized knowledge for both installation and troubleshooting.
2. Economic Factors: The sophisticated transducers and electronic components required result in a significantly higher initial purchase price compared to traditional flow-meters like orifice plates or rotameters. The cost is particularly high for "clamp-on" models that require high-precision sensors to transmit through pipe walls.
3. Sensitivity to Fluid Conditions: While not the "main" drawback in terms of generalized hardware, these meters can be severely affected by the presence of bubbles, suspended solids, or turbulence, which can scatter the ultrasonic signal and lead to measurement errors.
Therefore, the combination of advanced electronic requirements and high initial investment makes complexity and cost the primary drawbacks.