Questions and Answers
What is the total friction loss in psi for 300 feet of 3” hose flowing at 400 GPM?
How is the friction loss calculated for 2½” hose?
Which type of 2½” hose is used primarily during standpipe operations?
What is the average coefficient used for friction loss in a 3” hose?
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What is the maximum friction loss for 500 GPM through a 3” hose?
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During which conditions do most accidents involving fire apparatus occur?
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What type of license must drivers of authorized emergency vehicles possess in Florida?
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What does 'due regard' mean in the context of emergency vehicle operation?
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Which of the following factors is NOT considered when assessing reasonable safety for emergency vehicle operations?
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What potential consequences does a driver face for violating state statutes while operating emergency vehicles?
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Study Notes
Friction Loss in Hose
- Friction loss in 3” hose calculated for a flowing rate of 100 to 500 GPM ranging from 1 psi to 25 psi per 100 feet.
- Average coefficient for friction loss in 3” hose is 0.72.
- Total friction loss formula: FL = Q² x L, where Q is flow rate and L is hose length in hundreds.
Friction Loss for Different Sizes
- Friction loss in 2½” hose: calculated as 2 x Q² x L.
- Two types of 2.5” hose, Hi-Combat® (200 ft long) is pre-connected on the right rear of engines; Tru-ID 2.5® is available in four 50 ft bundles for easy deployment.
- Primary use of 2.5” hose includes standpipe operations.
Driving Operations and Responsibilities
- In Florida, emergency vehicle operators are not required to have a CDL but must possess a Class E license.
- Drivers must operate firefighting apparatus defensively and safely according to state laws and policies.
- “Due regard” means exercising caution and care similar to reasonable persons in similar circumstances.
Locating Water Sources
- Communication Center can assist in locating water sources.
- Water Source Locator software provides information on hydrants and static sources.
Relay Pumping Operations
- Used when the water source is remote; involves transferring water through hoses to the fire scene.
- The “source” engine pumps from the water source, while the “attack” engine is located at the fire scene.
- Larger pumps at water sources reduce friction loss; prefer using 5” hoses for less loss and maximum GPM.
Setup and Management of Dump Tanks
- Must be placed on level ground to maximize capacity; should include a salvage cover for protection.
- Supply engines should flow water back into dump tanks to maintain priming.
- A Water Supply Officer may be needed to coordinate relay pumping and water supply operations.
Friction Loss Calculations for Various Hoses
- Friction loss for flows less than 95 GPM is negligible; should round up to 100 GPM for calculations.
- For 5” hoses, use the 5” Hand Method in practical settings though coefficients are preferred in classrooms.
Practical Calculations Examples
- Calculating friction loss: For 400 ft of 3” hose flowing 300 GPM results in a loss of 25.92 psi.
- Using the coefficient method in practical settings enables standardized friction loss evaluations across hose sizes.
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Description
Test your understanding of friction loss calculations in hoses with this quiz. You'll explore how different flow rates affect the friction loss over a distance and apply the average coefficient for accurate calculations.
