If a rotameter is calibrated to measure a certain gas, what must be done to use it for a different gas?

To effectively use a rotameter calibrated for a specific gas with a different gas, recalibration is essential. This is due to the varying properties of gases, such as density, viscosity, and flow characteristics, which can significantly affect the accuracy of the flow measurement. A rotameter operates on the principle of buoyancy; therefore, the float's position within the tapered tube is influenced by the physical properties of the gas flowing through it.

When a different gas is introduced, its distinct properties will not correspond to the previous calibration data established for the first gas, potentially leading to inaccurate flow readings. Recalibrating ensures that the rotameter accurately reflects the flow rate of the new gas by adjusting the relationship between the float position and the actual volumetric flow rate specific to the new gas's characteristics.

Using the rotameter without recalibration or assuming that changing the gas does not require any adjustments can lead to significant errors in measurement, which can affect overall system efficiency and safety.