Which type of water meter has no moving parts?

The type of water meter that has no moving parts is the ultrasonic meter. Ultrasonic meters operate by sending ultrasonic sound waves through the water flow and measuring the time it takes for the sound waves to travel downstream and upstream. By calculating the difference in travel time, the meter can determine the velocity of the water flow, allowing it to accurately measure the flow rate without the need for any mechanical components that could wear out or malfunction over time.

In contrast, the Venturi meter, while effective for measuring flow, relies on the principle of differential pressure and has physical components that interact with the flow, which can be considered moving parts, especially if the design incorporates elements that adjust to variations in flow. Positive displacement meters function by trapping water in a measuring chamber and physically moving mechanisms to tally the volume, meaning they rely on moving parts. Magnetic meters measure flow based on magnetic fields but also contain parts that interact with the water flow, which does not align with the characteristic of having no moving parts.