What is the requirement for nozzles in a dry chemical extinguishing system?

The requirement for nozzles in a dry chemical extinguishing system focuses on their ability to ensure effective coverage of the protected area. This is crucial because an extinguishing system's effectiveness greatly depends on how well the extinguishing agent can be distributed over the intended surface that needs protection. Proper nozzle design and positioning play a significant role in achieving thorough and efficient coverage, which in turn maximizes the suppression of fire in the designated area.

Using nozzles that fail to provide comprehensive coverage could result in inadequately protected spaces, allowing the fire to persist or even grow. Therefore, ensuring that the nozzles are configured to deliver appropriate amounts of dry chemical agent uniformly across the area is a foundational safety requirement outlined in the NFPA 17 standards. This attention to coverage guarantees that the system functions effectively when called upon during a firefighting event.

The other options may suggest materials or functions that might seem relevant, but they do not capture the primary purpose of the nozzles within the context of system design and effectiveness. Therefore, effective coverage is a decisive factor in the requirements for nozzles in these systems.