AIR DUCTING AND LOSS OF CAPACITY
What are capacity losses in ducting
To transport air from and to the outdoors its necessary to channel the ventilation system using ducting. Once the system has been channelled a loss of capacity will be noted.
To minimize the dispersion of energy and reduce the loss of capacity its necessary to:
- section the duct (1,5 times minimum the diameter of the flange of the fan or exhaust)
- minimize the path of the ducting
- reduce to the minimum the section variations of the duct
- reduce to the minimum the change of directions in the ducts path
- eliminate any corners or turns in the ducts path
THE IN-LINE CHANNELLING OF THE VENTILATION SYSTEM USES:
- rigid ducting
- flexible ducting
- flexible acoustic insulted ducting
Usually, the rigid ducting, being smooth makes the path of the air more efficient and therefor reduces the capacity loss. Regarding changes of direction, its advised to cruve with a radius of at least 1,5-2 times the diameter of the ducting.
CALCULATE THE LOSS OF CAPICITY IN A DUCT
To calculate the loss of capacity per in-line meter in smooth ducts, its necessary measure in mm of column water. When the ducting is not smooth, one must resort to coefficient correction, with a certain approximation, to keep into consideration the rugged surface.
In the below table the capacity losses are indicated mmH20/ml