ASHRAE and SMACNA standards specify the duct sealing requirements in terms of seal classes A, B and C.
- Seal Class A - All transverse joints and longitudinal seams and duct wall penetrations shall be sealed. Pressure sensitive tape shall not be used as primary sealant. Max. 2 to 5 percent total system leakage.
- Seal Class B - All transverse joints and longitudinal seams shall be sealed. Pressure sensitive tape shall not be used as primary sealant. Max. 3 to 10 percent total system leakage.
- Seal Class C - All transverse joints shall be sealed. Max. 5 to 20 percent total system leakage.
- Unsealed - 10 to 40 percent total system leakage.
Systems for ventilation and air handling - air change rates, ducts and pressure drops, charts and diagrams and more.
Minor loss (pressure or head loss) coefficients for air duct components.
A major friction loss diagram for air ducts - Imperial units ranging 10 - 100 000 cfm.
Head loss or major loss in air ducts - equations and online calculator for rectangular and circular ducts - Imperial and SI units.
Calculate velocities in circular and rectangular ducts - imperial and SI-units - online calculator.
Thickness of sheet metal used in ductwork.
Recommended distance between ductwork support hangers.
Rectangular equivalent diameter for air flows between 100 - 50000 cfm.
Recommended air velocities in HVAC ducts.
Estimate noise generated by air flow in ducts.