For a fire sprinkler system without a Fire Department Connection (FDC), how is hydraulic pressure determined?

For a fire sprinkler system without a Fire Department Connection (FDC), how is hydraulic pressure determined?

• A. 150 psi
• B. 100 psi
• C. 60 psi
• D. Determined by hydraulic calculations to meet the most remote head

Answer: (D)

When a fire sprinkler system has no Fire Department Connection, you can’t rely on a preset pressure for the whole system. Instead, you design it using hydraulic calculations that model how water will flow from the source through the piping to every sprinkler head. These calculations account for pipe sizes and lengths, elevation differences, friction losses, fittings, and the required flow for the sprinklers. The goal is to ensure that, as water is flowing, the pressure at the most hydraulically remote head meets its operating requirement. That farthest point typically drives the design because it experiences the greatest losses; if it’s met there, all other heads should receive adequate pressure as well. Fixed pressures like 150 psi, 100 psi, or 60 psi don’t account for the building’s layout or height differences, so they aren’t universally correct.

When a fire sprinkler system has no Fire Department Connection, you can’t rely on a preset pressure for the whole system. Instead, you design it using hydraulic calculations that model how water will flow from the source through the piping to every sprinkler head. These calculations account for pipe sizes and lengths, elevation differences, friction losses, fittings, and the required flow for the sprinklers. The goal is to ensure that, as water is flowing, the pressure at the most hydraulically remote head meets its operating requirement. That farthest point typically drives the design because it experiences the greatest losses; if it’s met there, all other heads should receive adequate pressure as well. Fixed pressures like 150 psi, 100 psi, or 60 psi don’t account for the building’s layout or height differences, so they aren’t universally correct.