Which valve type uses a ball inside as the sealing element and is operated by a quarter-turn to open or close?

• A. Ball valve
• B. Globe valve
• C. Gate valve
• D. Butterfly valve

Answer: (A)

A ball valve uses a hollow ball as the sealing element. When you turn the handle a quarter turn (90 degrees), the ball’s bore aligns with the flow to open, and rotates out of alignment to close, creating a quick, tight shutoff. This simple mechanism gives fast operation and reliable sealing, which is why it’s the go-to choice for on/off isolation in wastewater piping. Other valve types—globe, gate, and butterfly—use different internal elements (disk, gate, or disc) and do not rely on a ball inside as the sealing element, so they don’t match this description as closely.