When testing positive displacement meters for accuracy, how many different flows are usually used?

• A. 2
• B. 3
• C. 4
• D. 5

Answer: (B)

Testing a positive displacement meter’s accuracy relies on checking its readings across the range of flows it will encounter in service. Because these meters can behave a bit differently at very low, intermediate, and high flows, you don’t want to rely on a single flow rate. Using three different flow rates—covering low, mid, and high portions of the meter’s operating range—lets you verify that the meter’s indication stays within tolerance throughout typical use and can reveal any nonlinearity or bias.

Three flow rates provide enough coverage to assess accuracy without overcomplicating the test. Using only two could miss errors that appear at one end of the range, while four or five flow points are more than what’s usually required for standard testing.