Difference between Ultrasonic Flow Meter and Electromagnetic Flow Meter

- Ultrasonic Flow Meter
It operates based on the propagation characteristics of sound waves:- Transit-Time Method (mainstream): Calculates the fluid flow velocity by measuring the time difference of sound wave propagation in downstream and upstream directions.
- Doppler Method: Calculates the fluid flow velocity by measuring the frequency shift of sound waves reflected by particles/bubbles in the fluid.
- Electromagnetic Flow Meter
It operates based on Faraday's Law of Electromagnetic Induction:
When a conductive liquid flows through a magnetic field, it cuts the magnetic induction lines and generates an induced voltage proportional to the flow velocity, which is then converted into the fluid flow velocity.

- Applicable Medium- Ultrasonic Flow Meter: No limitation on fluid conductivity
✅ Applicable to pure water, oil, alcohol, chemical solvents, sewage, and slurry.
✅ Compatible with partial gas media (special configuration required).
- Electromagnetic Flow Meter: The fluid must be conductive (conductivity ≥5μS/cm)
✅ Applicable to water, sewage, slurry, acid and alkali liquids, and paper pulp.
❌ Not applicable to pure water, deionized water, oil, gasoline, and gas.
- Measurement Accuracy- Ultrasonic Flow Meter: ±0.5%～±1% (Transit-Time Method)
- Electromagnetic Flow Meter: ±0.2%～±0.5% (higher accuracy)
- Installation Method- Ultrasonic Flow Meter: Clamp-on type is the core advantageous installation form
✅ No pipe cutting, no production shutdown required, and it can be installed only by being adsorbed on the outer wall of the pipe.
✅ Supports portable use and temporary flow measurement.
- Electromagnetic Flow Meter: The mainstream type is in-line with flange connection
✅ Must be installed by cutting the pipe and connecting it to the pipeline system.
- Installation Requirements- Ultrasonic Flow Meter: Full pipe condition is required; low requirement for straight pipe sections (10D upstream and 5D downstream, where D is the nominal pipe diameter).
- Electromagnetic Flow Meter: Strict full pipe condition must be met; higher requirement for straight pipe sections (5D upstream and 3D downstream, where D is the nominal pipe diameter).
- Cost Characteristics- Ultrasonic Flow Meter: The equipment cost has a low correlation with the pipe diameter, and it has extremely high cost performance in large-diameter working conditions.
- Electromagnetic Flow Meter: The equipment cost increases significantly with the rise of pipe diameter, and it is more economical in small-diameter working conditions.

Prefer Ultrasonic Flow Meter when:
Measuring non-conductive media (oil, pure water);
Non-shutdown and clamp-on installation is required;
Working conditions of large-diameter pipes (DN1000 and above);
Temporary/portable flow measurement scenarios.
- Prefer Electromagnetic Flow Meter when:
Measuring conductive media with impurities (slurry, mineral pulp, sewage);
Higher requirements for measurement accuracy are needed;
Working conditions of long-term fixed installation and small/medium-diameter pipes.