Flow meters act like "speed meters" for measuring the flow of liquids or gases. Common types include:
Mechanical: Measure flow through the rotation of an impeller or piston; simple in structure but prone to wear.
Electromagnetic: Utilizes the principle of electromagnetic induction; suitable for conductive liquids and with no pressure loss.
Ultrasonic: Calculates flow based on the time difference of sound wave propagation; easy to install but more expensive.
Thermal: Measures gas flow based on heat loss; fast response and high accuracy.