Evolution 4 — Attack Line with Elevation Change

Overview

Introduces elevation head pressure into the PDP calculation. The attack line runs to an upper floor, and the operator must account for the additional pressure needed to push water uphill. Every 10 feet of elevation adds approximately 4.34 PSI of back-pressure that the pump must overcome. This is a common real-world scenario for any department that responds to multi-story structures — apartments, commercial buildings, hotels. Forgetting to account for elevation is one of the most common PDP calculation errors, and it results in the crew on the upper floor receiving inadequate nozzle pressure. They call for more pressure, the operator increases throttle without understanding why, and the cycle of guesswork begins.

Training Objective

Supply an attack line to the third floor of a structure, correctly accounting for elevation pressure loss in the PDP calculation. The operator must deliver adequate nozzle pressure at the elevated position, not just at the pump panel.

Skills Practiced

• Elevation pressure calculation (0.434 PSI per foot of elevation)
• Multi-story operational awareness and floor-counting
• Adjusted PDP for vertical hose lays including standpipe friction
• Maintaining pressure under elevation demand without over-pressurising
• Understanding the difference between pump panel pressure and nozzle pressure at elevation
• Communicating with crews about floor changes that affect pressure

Setup

Hydrant supply with a single 1¾" attack line running to the third floor of a structure (approximately 30 feet of elevation). The elevation change adds roughly 13 PSI of back-pressure that must be factored into the pump discharge pressure on top of friction loss and nozzle pressure.

Scenario

A fire on the third floor of an apartment building. The attack crew has stretched a line up the interior stairwell and is preparing to make entry on the fire floor. They need water at the correct nozzle pressure despite the vertical distance from the pump to the nozzle. If the operator does not account for elevation, the crew will have a weak stream that cannot knock down the fire.

What to Expect

The simulation adds elevation pressure to the required PDP. Operators who forget to account for elevation will under-pressure the line by 10-15 PSI — enough to make the difference between an effective attack and a failed one. The scoring reflects whether the nozzle receives adequate pressure at the elevated position, not just whether the pump panel gauge looks correct.

Tips

• The rule of thumb: 5 PSI per floor above the pump (approximately 10-12 feet per floor)
• Elevation adds to your PDP — you need more throttle, not less
• Verify your calculation before opening the line — add NP + FL + elevation
• Watch for pressure changes if the crew moves between floors — going up one floor adds another 5 PSI of demand
• If the crew reports weak pressure, check your elevation calculation first before blindly increasing throttle
• On the fireground, always confirm which floor the crew is operating on — assumptions cause errors