Hvac Duct Fittings Equivalent Length Chart

Use the friction chart at 1000 cfm in 9 4 inch diameter to friction loss is 0 5 in water 100 ft.

Hvac duct fittings equivalent length chart. 12 x 7 flat oval 1000 cfm solution. Ordinary heating ventilating and air conditioning duct systems read air pressures at 0 4 psi or less often much less. Equivalent duct sizes for same friction loss from. The strength of the equivalent length method is that it is very simple to calculate.

This article details the calculation of pressure losses through pipe fittings and some minor equipment using the equivalent length method. Equivalent lengths become important to the hvac system designer who is looking to ensure proper airflow distribution with the equal friction method of duct sizing. From table a 3 the equivalent round size is 9 4 inches. A common duct pressure of 0 25 inches water column is equal to 0 25 divided by 27 7 in wc psi 0 009.

Each fitting has an effective length that equates its pressure drop to an equivalent amount of straight duct. 1 psi equals 27 7 inches of water gauge. Fittings such as elbows tees and valves represent a significant component of the pressure loss in most pipe systems. Energy vanguard this duct design shows the layout of a duct system including the fittings and duct sizes.

The weakness of the equivalent length method is that.