When measuring flow pressure with a hand-held pitot gauge, the tube should be:

When measuring flow pressure with a hand-held pitot gauge, the tube should be:

• A. Even with the end of the hydrant outlet
• B. Parallel to the outlet opening
• C. At a distance equal to the diameter of the outlet
• D. 1-1/4" from the end of the outlet

Answer: (B)

When you measure flow pressure with a hand-held pitot gauge, you want the sensing opening to sample the moving water without disturbing or blocking the flow. Positioning the tube so that it runs in line with the flow—i.e., parallel to the outlet opening—lets the tip face the oncoming water and measure the true stagnation pressure the jet carries. This orientation keeps the measurement within the main flow rather than at the edge or away from the center, which can distort the reading. If the tube were flush with the end of the hydrant outlet or placed at a fixed distance from the end, the reading could be affected by turbulence from the edge, boundary layer effects, or an incomplete sampling of the jet. Keeping it parallel to the outlet ensures the probe encounters a representative portion of the flow and yields a more accurate pressure reading.

When you measure flow pressure with a hand-held pitot gauge, you want the sensing opening to sample the moving water without disturbing or blocking the flow. Positioning the tube so that it runs in line with the flow—i.e., parallel to the outlet opening—lets the tip face the oncoming water and measure the true stagnation pressure the jet carries. This orientation keeps the measurement within the main flow rather than at the edge or away from the center, which can distort the reading.

If the tube were flush with the end of the hydrant outlet or placed at a fixed distance from the end, the reading could be affected by turbulence from the edge, boundary layer effects, or an incomplete sampling of the jet. Keeping it parallel to the outlet ensures the probe encounters a representative portion of the flow and yields a more accurate pressure reading.