Which material is NOT typically used in fire sprinkler systems?

Fire sprinkler systems are designed using materials that can withstand high pressures, corrosion, and the potential for fire exposure. Black steel pipe, CPVC pipe, and stainless steel are commonly used because they offer the necessary durability and resistance to the environment in which they operate.

Black steel pipe is favored for its strength and ability to withstand high pressures, making it suitable for underground and above-ground fire sprinkler applications. CPVC pipe is a plastic material specifically designed for fire protection systems, providing a lightweight and corrosion-resistant option. Stainless steel is also used due to its anti-corrosive properties and overall strength, especially in environments where moisture and chemicals may be present.

In contrast, fiberglass is not typically utilized in standard fire sprinkler systems. While fiberglass has applications in other industries due to its lightweight and corrosion-resistant qualities, it does not meet the established standards and codes required for fire sprinkler systems. This makes it unsuitable for reliable performance in the high-stress conditions that fire sprinkler systems may encounter. Therefore, D is the correct choice, as fiberglass is not a common or standard material used in fire sprinkler installations.