Which statement about anesthetic gas flowmeters is NOT true?

The chosen statement that the diameter of the flowmeter tube is smaller at the top than at the bottom is indeed not accurate. In flowmeters, the tube is typically designed with a consistent diameter that facilitates a predictable flow of gas. The tapering design, if present, generally allows for accuracy in measuring gas flow.

Understanding the construction of flowmeters is essential for safe anesthetic practices. The flow of gas is actually visually monitored by a bobbin or float, which moves through a flow tube. In terms of orientation, the safest position for an oxygen flowmeter is downstream from other gases, ensuring that oxygen is delivered last, which minimizes the risk of hypoxia.

The manipulation of the control knob is designed for ease of use, and turning it counterclockwise typically engages the gas flow, allowing practitioners to adjust the flow rate as needed. The bobbin's rotation within the flow tube reflects changes in gas flow, but it is not engaged constantly — it moves in response to the dynamic conditions of gas flow.