Relay / LDH
Relay / LDH Supply Drill
Set up a relay-style supply evolution with target flow, intake pressure, spacing discussion, and communication. This is an original FireOps Calc drill organizer for NFPA 1410-style training and department-level practice.
Use local standards: Set staffing, time benchmark, PPE, water flow, hose load, and pass/fail criteria from your department SOP and official NFPA documents. This page does not reproduce the official NFPA standard.
Objective
Practice relay pumping decision-making with emphasis on distance, hose size, desired flow, and intake pressure target.
Setup
- Two engine positions or cones marked as source and attack engine
- LDH or simulated supply line
- Desired flow card
- Radio communication between pump operators
Evolution flow
Set desired flow and total distance.
Use relay calculator or pump card to discuss engine spacing.
Source engine establishes discharge pressure.
Attack engine confirms intake pressure and supplies simulated attack lines.
Adjust pressure slowly by radio command.
Debrief target flow, intake pressure, and spacing.
Engineer focus
- Maintain adequate intake pressure
- Make one pressure change at a time
- Communicate clearly between pump operators
- Understand friction loss over long supply hose
- Do not exceed hose/apparatus limits
Common mistakes
- Changing pressure at both engines at the same time
- Ignoring intake pressure
- Using a relay when water supply does not support the desired flow
- Poor radio terminology
Evaluator sheet
Score and debrief
Use this as a printable quick score sheet. Add department-specific time targets and safety requirements before the drill.
Evaluation item
Result
Notes
Water established
Yes / Needs work
Line/device deployed safely
Yes / Needs work
Target pressure selected correctly
Yes / Needs work
Communication clear
Yes / Needs work
Kinks/hazards corrected
Yes / Needs work
Debrief completed
Yes / Needs work
After-action questions
- What was the first delay in the evolution?
- Was water available before the crew needed sustained flow?
- Was the pump pressure chosen from a known source or guessed?
- What did the engineer have to correct during the drill?
- What will the crew do differently on the next repetition?