They easily become blocked when used with fluids carrying particles.Ī convergent-divergent duct has a maximum diameter of 150 mm, and a Pitôt-static tube is placed in its throat. They can measure the flow rate only at a particular position in the cross-section of the pipe (iii) They produce only a small pressure loss in the tube (iv)ĭue to the small pressure difference, they are only suitable for high velocity fluids (ii) A development of the Pitot tube, a pitometer, tests the flow of water in water mains and detects leakages. In these cases, the tube is connected to a Bourdon pressure gauge which can be calibrated to read velocity directly. However, the main use of Pitot tubes is to measure the velocity of solid bodies moving through fluids, such as the velocity of ships and of low speed aircraft. Another use is the measurement of ventilating-duct air flows in mines. The device is generally unsuitable for routine measurements and in industry is often used for making preliminary tests of flow rate in order to specify permanent flow measuring equipment for a pipeline. The tubes canbe made very small compared with the size of the pipeline and the monitoring of flow velocity at particular points in the cross-section of a duct can be achieved. Most tubes incorporate a short external rod to ensure the probe is aligned to the axis of the duct.Ī Pitot-static tube may be used for both turbulent and non-turbulent flow. Alignment of the probe relative to the flow direction affects accuracy, though this amounts to about only 1% error in the recorded velocity pressure for up to 10° for both yaw and pitch. Normally it is not suitable for use below duct velocities of about 3.5 m/s. For site work, coefficient C may be taken as unity and the other corrections ignored.īecause of its simplicity and ease of use, the Pitot-static tube, connected to a suitable manometer, is used extensively in testing ventilation systems. These corrections, amounting to a total of approximately 2% in terms of the mean velocity resulting from a traverse, are usually reserved for laboratory work. In determining the flow rate from a Pitot-static tube traverse, additional corrections for effects such as tube blockage and turbulence are applied to the mean velocity.
#Using a pitot tube iso#
Values of C are published in ISO 3966:2008.
Due to change in velocity profile, it develops a very low differential pressure which is difficult to measure.Where C is the calibration coefficient for the tube. There is no standardization for pitot tubeĬhange in velocity profile may cause significant errors.
Pitot tubes have found limited applications in industries because they can easily become clogged with foreign materials in the liquid. Not suitable for dirty or sticky fluid like sewage disposal. Difference between pitot tube and Pitot-static tube Combined pitot tube (Prandtl Tube) and Double tip pitot tube Some types can also be easily removed from the pipeline. Due to its small size, It can introduce to fluid flow without shutting down the flow.Ĭan be easily installed in extreme environment, high temperature and pressure conditions They are used for mapping flow profile in a channel or duct.Īdvantages and Disadvantages of pitot tubes Advantagesĭo not contain moving parts this minimizes the frictional loss.Įasy to install. It is used in aircraft to measure air flow velocity. It is used in the air duct and pipe system.
Applications of pitot tubeThe pitot tube is used in utility streams where high accuracy is not necessary.