Which is NOT a valid reading position for the flowmeter ball?

• A. Bottom
• B. Center
• C. Top
• D. Left side

Answer: (D)

The flowmeter ball shows flow by its vertical position inside a clear vertical tube, and the value is read where the ball aligns with the calibrated marks on the scale. The ball can legitimately sit at the bottom (no flow), somewhere around the center (moderate flow), or near the top (high flow), because those positions correspond to the scale values. Reading from the left side isn’t a valid reading position because the scale is laid out for front-on, vertical viewing; looking from the side would introduce parallax and doesn’t align with the calibrated references. So the only non-usable option is reading from the left side.