A pitot tube can be used to measure fluid flow velocity by converting the kinetic energy in a fluid flow to potential energy. The principle is based on the Bernoulli Equation where each term of the equation can be interpreted as pressure. p + 1/2 ρ v 2 + ρ g h. = p + 1/2 ρ v 2 + γ h.
What is the pressure difference in a pitot tube?
Example Calculation Consider a pitot tube being used to measure air velocity in a heating duct. The air is at 85 oF and 16 psia. The pitot tube registers a pressure difference of 0.021 inches of water (Pstag – P).
When is a pitot traverse of a duct required?
If average duct speeds, or mass or volumetric flow rates are required, it is necessary to perform a Pitot traverse of the duct. This involves taking measurements at various positions across the duct. Before a traverse is conducted, it is necessary to select a suitable location to perform the survey.
How do you measure air velocity in a heating duct?
Consider a pitot tube being used to measure air velocity in a heating duct. The air is at 85 oF and 16 psia. The pitot tube registers a pressure difference of 0.021 inches of water (P stag – P).
What is the density of air in a pitot tube?
The charts below are based on air density 1.205 kg/m3 and water density 1000 kg/m3 . Note that as indicated in the diagram above – pitot tubes are not suited for low velocity flow. Due to low dynamic pressure (head) the readings will be inaccurate.
What is the impact pressure on a pitot tube?
The total impact pressure (PT) is the sum of the static and kinetic pressures and is detected as the flowing stream impacts on the pitot opening. To measure impact pressure, most pitot tubes use a small, sometimes L-shaped tube, with the opening directly facing the oncoming flowstream.
What is a pitot tube used to measure?
The Pitot Tube The pitot tube is a simple and convenient instrument to measure the difference between static, total and dynamic pressure (or head). The head – Δh – (or pressure difference – Δp) can be measured and calculated with the help of u-tube manometers, electronic pressure transmitters or similar instrumentation.
