Duct fitting pressure drop 1

[HVAC68]

The traditional method of calculation of duct fitting (bends, elbows, etc.) is based on equivalent length calculation.

There is also another method wherein we use the velocity pressure and multiply the same with a coefficient (k).

(h/4005) square x k.

Needless to say, both produces different results, the second one producing a higher static pressure drop through the duct.

Which one do we follow ?

HVAC68

 

[willard3]

SMACNA uses the velocity pressure method and so do I.

Velocity effects are very important in air systms.