What is the name of the valve on sprinkler systems that shows open or closed by a center screw in the valve stem?

What is the name of the valve on sprinkler systems that shows open or closed by a center screw in the valve stem?

• A. PIV
• B. Fusible Link
• C. Sprinkler
• D. OS&Y

Answer: (D)

OS&Y, Outside Screw and Yoke, is the valve type where the stem and its center screw extend outside the valve bonnet. The stem’s position rises when the valve is opened and lowers when it’s closed, providing a clear visual cue of open or closed status. This direct stem indication is why inspectors recognize it as the valve that shows its position by the screw in the stem. Other devices don’t use the stem in this way—the Post Indicator Valve shows status on a separate post, fusible links are heat-activated devices, and a generic sprinkler valve isn’t a specific stem-indicating type.

OS&Y, Outside Screw and Yoke, is the valve type where the stem and its center screw extend outside the valve bonnet. The stem’s position rises when the valve is opened and lowers when it’s closed, providing a clear visual cue of open or closed status. This direct stem indication is why inspectors recognize it as the valve that shows its position by the screw in the stem. Other devices don’t use the stem in this way—the Post Indicator Valve shows status on a separate post, fusible links are heat-activated devices, and a generic sprinkler valve isn’t a specific stem-indicating type.