Friction loss for reducer in sprinkler calculation

[morgan.z]

Can somebody please shed light on me about friction loss calculation for reducer in sprinkler calculation: NFPA 13 mentions elbow reducer in hydraulic calculation, but miss out on the equivalent length for reducer.It is common to use reducer after a tee in the branches. it is said equivalent length is not fit for reducer in some case . Do we need to calculate the friction loss for reducer in sprinkler pipe?
I look up other handbooks, a 3"/2" reducer is about 3 feet equivalent length , seems too big too ignore.
Really appreciate your help!

 

[UFT12]

Hydraulics for fire sprinklers are not like other hydraulics. For example, the turn of sprinklers directly screwed to tees or elbows is already accounted in the sprinkler K factor and therefore ignored. That typically includes the reducer as well. An other reason for such allowance is the hazen-williams equation which introduces error always on the safe side.

 

[morgan.z]

Thanks for your explanation.
i have not seen software like Elite fire has a equivalent length for reducer, not sure if to put in added equivalent length to the pipe. the NFPA 13 has mentioned the sprinkler nozzle directly screwed fittings to tees or elbows, reducer, but it says nothing about reducer in other places.
So i can interpret it that even the reducers after a tee in the branches DIRECTION can be ignored?