If you need to include a reducing elbow in your PIPE-FLO model, but don’t have any K factor data, you can use a combination of a reducer and elbow.
The standard table shipped with PIPE-FLO contains all of the valves and fittings found in the Crane Technical Paper No. 410. The Crane paper does not include K factor data for reducing elbows.
If your system contains a reducing elbow and you don’t have any K factor data for this type of fitting, you can conservatively model the elbow as a combination of the resistance due to a straight size elbow and a sudden enlargement (Ref. Crane Technical Paper No 410, Page 4-8).