Does the thickness and material of the insulation layer affect the measurement accuracy when a clamp-on ultrasonic flowmeter is installed on an insulated pipeline? Are special treatments required?

It has an indirect impact, but the core issues are not the insulation layer itself, but the air gaps between the insulation layer and the outer wall of the pipeline, as well as the coupling effect.

• If the insulation layer (e.g., rock wool, polyurethane) fits tightly against the outer wall of the pipeline and has a thickness ≤ 50mm, its impact on ultrasonic attenuation is minimal (with an error usually < 0.3%).
• If the insulation layer ages and forms internal air gaps (air has extremely strong attenuation on ultrasonic waves), or if the thickness > 100mm, the signal strength will drop sharply, and the accuracy error can expand to more than ±5%.

Treatment Methods:

1. Preferred method (when insulation removal is feasible): Strip off the insulation layer at the installation point (the stripped area should be slightly larger than the sensor base), clean rust and oil stains from the outer wall of the pipeline, and then use a special coupling agent (instead of ordinary butter) to fit the sensor tightly against the outer wall of the pipeline.
2. Alternative method (when insulation cannot be stripped): Select a high-temperature compatible sensor and match it with an extended probe (the length of the probe should be slightly longer than the thickness of the insulation layer) to make direct contact with the outer wall of the pipeline.