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Pitot tube is a mechanical device which is used to measure velocity of flow at any point in a pipe or a channel. It was invented by French engineer Henri Pitot and modified by French scientist Henry Darcy.
Pitot Tube works on a basic principal of fluid Mechanics and that is, if a fluid stops flowing, all its kinetic energy gets converted into pressure energy. It helps us in measuring that pressure energy of stopped fluid.
Since kinetic energy is directly proportional to square of velocity, we can easily calculate velocity of flow.
Types of pitot tubes
- Simple pitot tube
- Static source
- Pitot-static tube
Types of pitot tube arrangements (in case of Pipe)
- Pitot tube along with a vertical piezometer tube
- Pitot tube connected with piezometer tube
- Pitot tube and vertical piezometer tube connected with a differential U-Tube manometer
- Pitot static tube
Applications of Pitot Tube
- It is used to measure speed of an aircraft
- It is used to measure speed of a boat
- It is used to measure fluid flows in different industries
- It is used where very high accuracy is not required
- It is used to measure flow profile in a duct or channel
- In general pitot tube is used to measure velocity of flow
Advantages of pitot tube
- It is easy and economical to install and remove
- It has no moving parts which helps in minimizing frictional losses
- It is small in size
- It is low in cost
- It causes very less pressure loss
Limitations or disadvantages of pitot tube
- Any foreign material in flow, can change the accurate reading.
- Its accuracy is not that good
- It has low rangeability
- It has low sensitivity
- It works better in high velocity flow
- A change in velocity profile can cause significant changes in readings
- It cannot be used with dirty fluids
- Its sensitivity gets disturbed by flow direction
Image sources:
Tube types: By Chaos386 – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=3301685