Couplings and unions not of the screwed type should be...

Couplings and unions that are not of the screwed type need to be specifically listed for use in sprinkler systems to ensure they meet the necessary safety and performance standards. This requirement helps to guarantee that all components of the sprinkler system are compatible and reliable under the conditions they will face during operation, including pressure, temperature, and the potential for exposure to water or other substances.

Using components that are specifically listed ensures that they have been tested and approved for the intended use, providing confidence that they can handle the demands of a fire suppression system. This standardization is crucial in maintaining the integrity and effectiveness of the overall sprinkler system in protecting life and property.

On the other hand, options suggesting that these components could be ignored or made from any material do not prioritize safety and structural integrity. Additionally, while cost and availability are practical concerns, they should not compromise the quality or suitability of the fittings used in fire protection systems.