Which of the following oxygen flowmeters is NOT affected by gravity and can be used in any position when attached to an oxygen cylinder?

• A. Bourdon-gauge flowmeter
• B. Ball-and-float flowmeter
• C. Pressure-compensated flowmeter
• D. Vertical-position flowmeter

Answer: (A)

The main idea is that some oxygen flow devices rely on gravity to work, while others use pressure regulation that doesn’t depend on orientation. A Bourdon-gauge flowmeter is built into the regulator and uses a calibrated orifice with a spring-loaded valve to set flow, so the delivered flow is determined by the regulator setting rather than the height of a float. Because there’s no floating element whose position is gravity-dependent, its performance isn’t affected by how the cylinder is oriented, so it can be used in any position when attached to a cylinder.

In contrast, a ball-and-float flowmeter relies on a float rising in a tapered tube, which requires a vertical orientation to read correctly; tilting or placing it in any other position changes the reading. A vertical-position flowmeter is designed to be upright and would be inaccurate if not. A pressure-compensated flowmeter aims to maintain a constant flow amid downstream pressure changes, but it’s a more complex design and isn’t what’s typically described as a gravity-independent flowmeter for use in any orientation on a cylinder.