46.02
16397 Rev A Updated 03/2021 © 2021 Victaulic Company. All rights reserved.
5.0 PERFORMANCE (CONTINUED)
Obstructions
The following guidelines outline criteria to minimize critical
obstructions to spray pattern development and to maximize
effectiveness in achieving control.
General
• Structural trusses and web members are not
considered "obstructions" provided a minimum 6"
lateral distance from sprinklers to side of truss/web
member is maintained.
• FL-SA/RE and FL-SA/DS sprinklers may be installed
directly on maximum nominal 2½" (DN65) pipe without
the need for a "Sprig-up". For pipe larger than 2½"
nominal, see NPFA 13 for Sprig requirements.
• Sprinklers shall be positioned away from obstructions
a minimum distance of Four (4) times the maximum
dimension of the obstruction (e.g. Ducts, pipe). This
4X requirement does not apply to truss web members
provided the web members do not exceed 6” and
the minimum lateral distance of 6” from sprinkler to
side of member is maintained.
Obstruction criteria is otherwise grouped into three
categories (See Figure 25, Figure 26 and Figure 27)
•
Vertical Obstructions
Those obstructions which run vertically through the
attic. These may consist of fireplace flues, walls,
vents, stacks, etc. These obstructions will typically
run up to or penetrate the roof deck.
•
Suspended Horizontal Obstructions
Those obstructions which are typically "suspended"
within the attic space itself and run horizontally.
These obstructions will have clearance over and
under the obstruction to allow discharge of water
around the obstruction. These obstructions may
consist of ductwork; walkways; etc. Horizontal
obstructions located within 1’-0” vertically of the
bottom chords or ceiling joists are not considered
“Suspended” Horizontal Obstructions.
•
Obstructions at Upper Deck
Those obstructions which are either attached directly
to the roof deck or to the top chords/joists of the roof
framing in a manner that little to no discharge of water
can pass/clear the top of the obstruction. These
obstructions can have an impact on the upper
portion of the spray pattern from sprinklers.
FL-SA/RE/FL-SA/DS
Should the sprinkler not be able to be located a distance of 4X away
from obstruction, an additional sprinkler must be installed on the
opposite side of the obstruction within 1'-0" from the opposite side
of the obstruction.
FIGURE 25: VERTICAL OBSTRUCTIONS
FL-SA/RE/FL-SA/DS SPRINKLERS
No additional sprinkler required below,
if equal to or less than 48" suspended obstruction.
FIGURE 26A
FIGURE 26B
Additional sprinkler required below,
if greater than 48" suspended obstruction.
FIGURE 26C
FIGURE 26:
SUSPENDED HORIZONTAL OBSTRUCTIONS
FL-SA/RE/FL-SA/DS SPRINKLERS
22
