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Difficulty: MediumDirect Fact Retrieval

During structural firefighting operations, nozzle operators must adjust variable gallonage fog nozzles depending on interior thermal conditions. When transitioning from direct attack to hydraulic ventilation, crews set the nozzle to a 30-degree wide fog pattern while operating at a standard nozzle pressure of 100 psi. To effectively draw smoke and toxic gases out of an opening, the nozzle tip must be positioned between four and six feet back from an open window or doorway. Placing the nozzle closer disrupts the entrainment airflow and forces heated gases back into the compartment.

According to the passage, how far from an open window or doorway should the nozzle tip be positioned during hydraulic ventilation?

  1. A
    Thirty feet away
  2. Between four and six feetAnswer
  3. C
    One hundred feet away
  4. D
    Directly against the sill to seal the opening

Answer

Between four and six feet
The author directly states that during hydraulic ventilation, the nozzle tip must be positioned between four and six feet back from an open window or doorway to draw out smoke and gases effectively.

Step-by-Step Solution

1
Locate the portion of the passage addressing the physical positioning of the nozzle tip during hydraulic ventilation.
Identified sentence: 'To effectively draw smoke and toxic gases out of an opening, the nozzle tip must be positioned between four and six feet back from an open window or doorway.'
Direct fact retrieval requires matching the specific condition in the stem with the explicit statement in the text.
2
Extract the exact measurement specified for distance.
The specified distance is between four and six feet.
Other numerical figures in the text (30 degrees and 100 psi) describe spray angle and pressure rather than distance.

Key Concept

Direct Fact Retrieval
Estimated Time:1m 0s
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Topics

Direct Fact Retrieval

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