Podcast
Questions and Answers
What should be done to prevent violent movement during relay operations?
What should be done to prevent violent movement during relay operations?
- Increase the pressure at the intake source.
- Monitor the GPM targets throughout the operation.
- Ensure all personnel are evacuated from the area.
- Secure the bleed-off lines effectively. (correct)
What is the maximum rated capacity of a Source Apparatus operating at a residual intake pressure of 20 PSI?
What is the maximum rated capacity of a Source Apparatus operating at a residual intake pressure of 20 PSI?
- The capacity cannot be determined from this information. (correct)
- 180 PSI EDP
- 150 PSI EDP
- 100 PSI EDP
Why is slowly opening and closing valves important in relay operations?
Why is slowly opening and closing valves important in relay operations?
- To adjust the water temperature during operation.
- To prevent water hammer and unexpected pressure changes. (correct)
- To maintain a constant pressure throughout the system.
- To ensure quick adjustments to flow rates.
At what EDP pressure does the maximum capacity of Source Apparatus from draft start to decrease?
At what EDP pressure does the maximum capacity of Source Apparatus from draft start to decrease?
What risk is associated with utilizing portable hydrants in place of hydrant assist valves?
What risk is associated with utilizing portable hydrants in place of hydrant assist valves?
What should the initial pressure be set at when the target GPM is unknown?
What should the initial pressure be set at when the target GPM is unknown?
What happens to the capacity of Source Apparatus at 200 PSI EDP while operating from draft?
What happens to the capacity of Source Apparatus at 200 PSI EDP while operating from draft?
Which of the following is not a recommended practice when coordinating a relay pumping operation?
Which of the following is not a recommended practice when coordinating a relay pumping operation?
What is the primary purpose of relay pumping in fire suppression?
What is the primary purpose of relay pumping in fire suppression?
What does the constant pressure relay method rely on to function effectively?
What does the constant pressure relay method rely on to function effectively?
Which riding position is responsible for operating the pump on a suppression apparatus?
Which riding position is responsible for operating the pump on a suppression apparatus?
In the context of relay pumping, what is a 'bleed-off line' primarily used for?
In the context of relay pumping, what is a 'bleed-off line' primarily used for?
Which method of relay pumping allows for the greatest distance of water flow?
Which method of relay pumping allows for the greatest distance of water flow?
What does the spacing and number of relay apparatus depend upon?
What does the spacing and number of relay apparatus depend upon?
Which of the following statements is true regarding personnel riding the apparatus?
Which of the following statements is true regarding personnel riding the apparatus?
What is the role of relay apparatus in relay pumping?
What is the role of relay apparatus in relay pumping?
What is the maximum distance allowed between apparatus for a GPM of 1500?
What is the maximum distance allowed between apparatus for a GPM of 1500?
Which valve must be used to connect a 5” supply line to the discharge during relay operations?
Which valve must be used to connect a 5” supply line to the discharge during relay operations?
During relay operations, which pressure governs the setting for the Source Apparatus?
During relay operations, which pressure governs the setting for the Source Apparatus?
What should be done if the intake pressure falls below 20 PSI during relay operations?
What should be done if the intake pressure falls below 20 PSI during relay operations?
Which action is NOT recommended when shutting down relay operations?
Which action is NOT recommended when shutting down relay operations?
What indicator should be watched to prevent cavitation during relay operations?
What indicator should be watched to prevent cavitation during relay operations?
What must be connected to every apparatus from the Source Apparatus to the Attack Apparatus?
What must be connected to every apparatus from the Source Apparatus to the Attack Apparatus?
What is the maximum operational pressure required for relay operations if it exceeds 200 PSI?
What is the maximum operational pressure required for relay operations if it exceeds 200 PSI?
Which factor is essential for determining the need for a relay pumping operation?
Which factor is essential for determining the need for a relay pumping operation?
Which of the following is a key component of the relay apparatus?
Which of the following is a key component of the relay apparatus?
What is indicated when a 20 PSI residual pressure is reached on the intake gauge?
What is indicated when a 20 PSI residual pressure is reached on the intake gauge?
What is the purpose of the crank handle on the hydrant assist valve during operations?
What is the purpose of the crank handle on the hydrant assist valve during operations?
Which GPM can sustain a maximum distance of 2000 feet between apparatus?
Which GPM can sustain a maximum distance of 2000 feet between apparatus?
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Study Notes
Relay Pumping Overview
- Relay pumping is essential when waterflow requirements and hose lay lengths exceed a single apparatus's capacity.
- It involves multiple apparatus positioned strategically to ensure water delivery to a fire scene.
- Spacing and number of units depend on waterflow demands and hose length needed.
Apparatus Designation
- Four designated positions on suppression apparatus:
- Unit Officer
- Driver/Operator (D/O)
- Hydrant Firefighter (behind D/O)
- Nozzle Firefighter (behind Unit Officer)
- Riding on the tailboard of Miami-Dade Fire Rescue apparatus is prohibited.
Key Components
- Attack Apparatus: The unit utilized directly at the fire scene for fighting the fire.
- Bleed-Off Line: A 50' x 3" hose section to discharge excess water, aiding pressure management and pump temperature control.
- Constant Pressure Relay Method: Maintains maximum flow using consistent pressure.
- Maximum Distance Relay Method: Pumps a predetermined volume for the maximum possible distance through the hose.
Relay Pumping Procedures
- Determination of relay necessity is based on friction loss and pressure capabilities of 5" hose.
- A chart outlines maximum distances for various flow rates (GPM):
- 1000 GPM: 2000 ft
- 1250 GPM: 1300 ft
- 1500 GPM: 900 ft
- 2000 GPM: 500 ft
Conducting Hose Lay
- Source Apparatus connects to hydrant or drafting source.
- Relay Apparatus lays the maximum hose length permitted and connects through the hydrant assist valve.
- Involves various connections including a 4½" NST male x 5" Storz adapter and additional 5" supply connections.
Starting Relay Operations
- Begin at the Source Apparatus, gradually working toward the Attack Apparatus.
- Set proper Engine Discharge Pressure (EDP) which equals friction loss + 20 PSI.
- Notify key personnel when water volume is depleted.
Relay Apparatus Role
- Receives and delivers water downstream while managing bleed air as necessary.
- Must maintain adjusted pressure and be aware of end-point capacities.
Stopping Relay Operations
- Reverse order of starting procedure, ensuring controlled throttling and safe shut down of discharges.
- Essential to prevent over-pressurization and system damage.
Cautions and General Information
- Coordination is crucial to avoid high pressures that could rupture hoses.
- Continuous radio communication is vital between Driver/Operators (D/Os) for operational safety.
- Adjustments to pressures must be minimal, as minor changes can affect the entire relay.
- Ensure bleed-off lines are secured to prevent hazardous movement.
Alternate Connection Method
- Use of portable hydrants instead of hydrant assist valves is possible but not advised due to operational interruptions.
- Mechanical failure in Relay Apparatus can disrupt water flow entirely through this method.
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