How is a flowmeter primarily calibrated for reading working pressure?

A flowmeter is primarily calibrated for reading working pressure using a calibrated glass tube with a floating ball. This method allows for a direct visual indication of the gas flow rate. The glass tube is designed to maintain a consistent cross-sectional area, and as gas flows through, the floating ball rises to a level that corresponds to the specific flow rate indicated on the scale printed along the side of the tube. This setup is particularly useful in the welding industry, where precise control of gas flow is crucial for optimal welding performance.

While other devices like digital displays or pressure gauges can provide readings related to pressure and flow, they do not directly measure the flow rate in the same intuitive manner as a glass tube with a floating ball. Manual dials might provide indications of pressure, but they lack the direct flow measurement and are generally less user-friendly for determining gas flow in welding applications.