The diameter of the manifold pipe shall be determined by the following equation:
For SI: 1 inch = 25.4 mm.
Fi = 9.8 × 10-4 Qi
Q = Nq
The fraction of the total head loss at the manifold segment, f, shall be less than or equal to 0.1. The in-line pressure at the distal end of the lateral, hd, shall be not less than 2.5 feet (762 mm) of head. Distribution pipes shall be connected to the manifold with tees or 90-degree (1.57 rad) ells. Distribution pipes shall have the ends capped.