Arizona Plumbing Practice Exam 2025 - Free Plumbing Practice Questions and Study Guide

The type of valve that must be installed at each building water supply line is the full open gate valve. This valve is specifically designed to allow for unrestricted flow of water in the supply line when in the open position. Its primary purpose is to serve as a shutoff valve, enabling the water supply to be easily turned on or off for maintenance or emergency situations. Furthermore, a full open gate valve does not create significant flow resistance, making it ideal for scenarios where water needs to flow freely without pressure loss.

In comparison, other types of valves like butterfly valves and globe valves may be used in specific applications but are not generally required at the water supply line entry. Butterfly valves are commonly used for throttling and regulating flow but may not provide the complete shutoff capabilities as effectively as a gate valve. Globe valves are designed for flow regulation and can restrict the flow path, making them less suitable for a direct supply line where minimal resistance to flow is desired. A check valve, while important for preventing backflow, does not serve as a shutoff valve and cannot be relied upon solely for isolating a water supply line.