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Pressure drop in circular ventilation channels.

Ventilation pipe with circular section

Calculates the pressure drop or the dynamic pressure drop of a channel part suction or blowing air (ventilation channel).
For circuits composed by different parts with different sections is necessary calculate separately and sum the results of each part.

Data input
Pipe characteristic.

Selection of tube material

Notes on the material

Absolute roughness of the inner wall

Wait roughness value.


Inner diameter of the tube

Ø i (mm)

Gas velocity in the channel.

Required flow rate


Normal values for civil and silent applications..
Conditioning public places, home and office, space heating in general, air recirculation system, fume exhaust.
Normal values for industrial applications.
Heating or cooling system, circulating ovens at a low temperature, air recirculation system for environments, fume extraction and harmful gases.
Normal values for special applications.
Suction shavings, pneumatic conveying of solids (eg plastic granules), pieces cooling after molding, power cyclones separators powders, implants for compressed air and other gases.
Gas characteristics.

Selection of the gas to be carried

Gas density

Wait load gas parameter.


Circuit components.
Circular straight pipe.

Channel lenght


Right deviation angle.

Angle deviation


Circular curve of 90 degrees realized by three straights.

90 degrees curve (in 3 parts)


Ratio R/D

R (mm)

Circular curve of 90 degrees with started flow.

90 degrees curve


Ratio R/D

R (mm)

Wait calculate
Gas velocity in the pipe m/s
Relative roughness on the inner wall r/d
Reynolds number
Friction coefficient (Colebrook)
Result of dynamic pressure drop mm H2O


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