A ___________ seat ring is a ____________ ring mounted in the body of a ____________, against which the moving disc of the valve closes.

• A. Bronze, machined, hydrant, or valve
• B. Bronze, cast, hydrant, or valve
• C. Brass, machined, hydrant, or valve
• D. Bronze, rough, hydrant, or valve

Answer: (D)

The seal inside a valve or hydrant is created by a seat ring, which provides the mating surface for the moving disc as it closes to stop flow. Bronze is a common choice for this seating surface because it stands up well to repeated contact with metal, resists corrosion in potable water, and can be finished to a durable wear surface. A rough finish on the seat ring is typical in hydrants and valves, offering reliable seating and wear characteristics in field service where debris and wear are factors; the ring is mounted inside the body of the hydrant or valve, serving as the fixed surface that the disc presses against to seal. While a machined, very smooth seat can be used in some designs, the standard description you’re studying emphasizes bronze with a rough seating surface for these components.