All standard products can be used for the exhaust air duct:
- Flexible pipes
- Galvanised metal ducts or pipes
- Connectors, adapters, and diverters for flat duct systems and pipe systems
- Wall boxes for evaporation into the open air or into a ventilation shaft
- Adapters on rectangular ducts
- Rectangular ducts or plastic pipes
- Backpressure flap
The material must be heat resistant up to 80oC and moisture resistant
The type and length of the exhaust air duct, particularly elbows or bends with small radii, can impede the air flow. -> keep diameter reductions and pressure losses(resistance) to a minimum.
The following must be avoided
Pressure losses through friction
- Long exhaust air ducts
- Exhaust air ducts with small diameters
- Exhaust air ducts with many bends and elbows
Duct or pipe friction resistance, i.e. friction on the inside of the exhaust air duct, affects the air flow as follows:
Pressure losses due to pictures
- The smoother the internal wall
- The larger the diameter of the internal wall
- The shorter the pipe, the lower the friction resistance.
The exhaust air encounters further resistance through fixtures built into the pipe, e.g. diverters(bends, elbows, angles), wall boxes with grids or back pressure flaps.
In order to ensure the minimum required air flow, a certain pressure loss(resistance) must not be exceeded.
The permissible total pressure loss in an individual pressure loss values for the straight pieces and fixtures in the exhaust air duct
The value for the maximum premissible total pressure loss for an exhaust air duct is 50*.
If the pipe connection has an inside diameter >100mm and a total pressure loss greater than 50*, increase the inside diameter of the pipe connection