Resources, Tools and Basic Information for Engineering and Design of Technical Applications!
mobile - visible on handheld devices - alternatively go to www.engineeringtoolbox.com!
Engineering ToolBox > Friction Loss - Temperature and Pressure
Most of the friction loss diagrams and tables available for air ducts are estimated for air at Normal Temperature and Pressure - NTP - conditions (20oC and 1 bar).
If the actual temperature condition is otherwise the friction loss can be compensated like
Δp = kt ΔpNTP (1)
where
Δp = actual friction loss (pressure or head)
kt = temperature compensating coefficient
ΔpNTP = friction loss at NTP conditions (pressure or head)
The temperature compensating coefficient can be estimated with the diagram below:
If the actual pressure is otherwise the friction loss can be compensated like
Δp = kp ΔpNTP (2)
where
Δp = actual friction loss (pressure or head)
kp = pressure compensating coefficient
ΔpNTP = friction loss at NTP conditions (pressure or head)
The pressure compensating coefficient can be estimated with the diagram below:
1000 mbar = 1 bar = 105 Pa (N/m2) = 0.1 N/mm2 = 10,197 kp/m2 = 10.20 m H2O = 0.9869 atm = 14.50 psi (lbf/in2) = 106 dyn/cm2 = 750 mmHg