How should a mag flowmeter be installed?

• A. Horizontally
• B. Vertically, upward
• C. Any orientation
• D. Diagonal

Answer: (B)

Magnetic flowmeters measure flow by detecting a voltage induced as a conductive liquid moves through a magnetic field. The accuracy relies on having a fully filled pipe so the electrical path between the electrodes is continuous; any gas pockets, air, or vapor disrupt the conduction path and distort the signal.

Installing the meter with the flow upward helps keep the line filled and allows any entrained air to rise to the top and be vented, preserving a single-phase liquid in the sensing region. This orientation reduces the chance of air pockets forming in the measuring section, which supports stable, accurate readings. While a fully filled pipe is the key requirement that can be met in other orientations under proper piping design, vertical upward flow is a common best practice to maximize reliability.