g
System Resistance
|
|
| return duct |
|
| fan | supply duct |
|
|
| |
damper | cooling |
| return air grille |
|
| ||
| coil |
|
|
|
|
| supply |
|
|
| diffuser |
g EH
x
Now that a typical fan performance curve has been developed, let’s see how the fan will perform within a system.
With each airflow, an air distribution system imposes a certain resistance to the passage of air. The resistance is the sum of all of the pressure losses experienced as air passes through the ductwork, supply air diffusers, return air grilles, dampers, filters, coils, etc. This is the resistance, or
System Resistance
static pressure
2.0 in. H2O
[491 Pa]
3,500 cfm
[1.65 m3/s]
airflow | g EI |
|
Assume that a system is designed to deliver 3,500 cfm [1.65 m9/s], and that to overcome the system pressure losses, the fan must generate 2.0 in. H8O [491 Pa] of static pressure.
To illustrate how a system resistance curve is developed, this point is plotted on the same chart used to develop the fan curve.
caQ3caM6793O[ | 7? |
