Sorry - I was just responding to an inquiry about side by side obstructions less than 4'-0" in ESFR system. Was supposed to be linked to thread but didn't turn out that way...
8.12.5.3.2 Bottom Chords of Bar Joists or Open Trusses.
ESFR sprinklers shall be positioned a minimum of 1 ft
(300 mm) horizontally from the nearest edge to any bottom
chord of a bar joist or open truss.
8.12.5.3.2.1 The requirements of 8.12.5.3.2 shall not apply
where upright sprinklers are...