Flow measurement is the quantification of the movement of a fluid (liquid or gas) through a pipeline or open channel. Accurate flow measurement is crucial in various industries, including water treatment, oil and gas, chemical processing, HVAC, and manufacturing, to ensure efficient operation, process control, and safety.

Types of Flow Meters:

1. Differential Pressure Flow Meters: Measure the pressure drop across an obstruction in the flow path.

   • Orifice Plate: Uses a flat plate with a hole, creating a pressure drop that is proportional to the flow rate.
   • Venturi Tube: Features a gradually narrowing throat that increases fluid velocity and decreases pressure.
   • Flow Nozzle: Similar to a venturi tube but with a simpler design and higher pressure drop.

2. Positive Displacement Flow Meters: Measure the volume of fluid passing through by repeatedly filling and emptying chambers.

   • Rotary Vane: Utilizes a rotor with vanes that trap fluid and move it through the meter.
   • Gear: Uses interlocking gears to measure the fluid flow.
   • Piston: Features pistons that move in response to fluid flow, measuring the volume directly.

3. Velocity Flow Meters: Measure the velocity of the fluid to determine the flow rate.

   • Turbine: Uses a rotor that spins with the flow; the rotational speed is proportional to the flow rate.
   • Electromagnetic: Measures flow rate using Faraday's law of electromagnetic induction; suitable for conductive liquids.
   • Ultrasonic: Utilizes ultrasonic waves; can be Doppler-based (measuring the frequency shift) or transit-time-based (measuring the time difference between pulses).

4. Mass Flow Meters: Measure the mass flow rate directly rather than volume.

   • Coriolis: Uses the Coriolis effect to measure the mass flow rate; highly accurate for a wide range of fluids.
   • Thermal: Measures the cooling effect of the fluid as it flows past a heated sensor; commonly used for gases.

5. Open Channel Flow Meters: Measure flow in open channels, such as rivers or drainage systems.

   • Weirs: Use a barrier with a notch to measure flow based on the height of the fluid passing over it.
   • Flumes: Use a specially shaped channel to measure flow based on the height and velocity of the fluid.

Selection Criteria:

• Fluid Type: The nature of the fluid (liquid, gas, slurry) and its properties (viscosity, conductivity, etc.).
• Flow Range: The expected flow rate range that the meter needs to measure.
• Accuracy: The precision required for the application.
• Pressure and Temperature Conditions: Operating conditions of the system.
• Installation Requirements: Space, orientation, and connection types.
• Output Signal: Type of electrical signal output needed for the control system.

Contact EML for flow measurement.