Plans, Calculations, and Working Drawings
What this domain tests
This domain tests whether you can prepare and review working plans, hydraulic calculations, and submittal packages. The exam emphasizes remote-area selection, node analysis, scale and legend requirements, and coordination with architectural and structural drawings.
Core rules and concepts
- Working plans typically show floor plans, elevations, riser details, pipe sizes, sprinkler locations, hanger locations, and the location of control valves and test connections.
- Hydraulic calculations must identify the remote area, the nodes, pipe lengths, elevations, fittings, and the supply curve. The calculation must match the plans.
- The remote area is the hydraulically most demanding area, not simply the farthest area on the drawing.
- Dry-pipe and double-interlock preaction systems increase the design area by 30 percent; the calculation must show that increase.
- Plans must be drawn to a stated scale and include a north arrow, legend, and revision block.
- Submittals must be coordinated with the AHJ's plan review requirements and with other trades.
Worked example
A hydraulic calculation for an Ordinary Hazard Group 1 dry-pipe system shows 1,500 ft2 at 0.15 gpm/ft2. That is the wet-system area. For a dry system, increase the area by 30 percent: 1,500 x 1.30 = 1,950 ft2. Sprinkler demand becomes 1,950 x 0.15 = 292.5 gpm, plus 250 gpm hose allowance, for 542.5 gpm total. If the calculation still shows 1,500 ft2, the submittal is deficient regardless of how clean the drawing looks.
Traps that cost marks
- Selecting the physically farthest area instead of the hydraulically most demanding area.
- Forgetting the 30 percent dry-system area increase.
- A calculation that does not match the pipe sizes or sprinkler locations on the plan.
- Missing elevation nodes, fitting losses, or the supply curve.
- Submitting without the AHJ-required scale, legend, or revision information.
Exam approach
Compare plan, calculation, and supply data as a set. Check the remote area, system type, hose allowance, and node-by-node consistency before accepting the package.