Which flowmeter is characterized as the simplest and least expensive device?

The flow restrictor is recognized as the simplest and least expensive device among the various types of flowmeters used for measuring gas flows. This device operates based on a fixed orifice that allows gas to flow through at a specific rate, depending on the pressure differential across the orifice. Its uncomplicated design eliminates the need for complex mechanisms or calibration that are often necessary in other types of flowmeters, such as Bourdon gauges or Thorpe tubes.

Because flow restrictors lack moving parts and digital components, they can be produced at a lower cost, making them a cost-effective solution for basic applications where precise flow measurement is less critical. They are ideal for scenarios where a constant flow of gas is required, allowing for straightforward implementation without the need for extensive maintenance or calibration.

In contrast, other types of flowmeters, such as rotameters and Thorpe tubes, involve more intricate designs that include float mechanisms or calibrated transparent tubes, which contribute to higher production costs and complexity. Hence, the flow restrictor stands out for its simplicity and affordability, making it a practical choice in many medical gas applications where basic flow measurement suffices.