Which sprinkler system valve uses a threaded shaft to indicate the position of the valve?

The outside stem and yoke valve is designed with a threaded shaft that extends through the yoke, which allows the user to see the open or closed position of the valve from a distance. When the valve is opened, the threaded stem moves outward, providing a clear visual indicator. This design is particularly beneficial in firefighting applications because it allows personnel to quickly assess the status of the valve without needing to be in close proximity, which could be essential if visibility is poor or if the area is hazardous.

In contrast, the inspector's test valve is used primarily to verify that the sprinkler system is operating correctly, but it does not utilize a threaded shaft mechanism for position indication. The wall post indicator and post indicator valves also serve as visual indicators of valve status, but they typically use a different mechanism, such as a disc or pointer, to show whether the valve is open or closed. The outside stem and yoke valve's design provides an effective and easily recognizable method for monitoring valve status, making it a reliable choice in fire protection systems.