What type of valve can show if it is open or closed?

The type of valve that can clearly show whether it is open or closed is an indicating valve. This valve is specifically designed with a mechanism that provides a visual or physical indication of its position. This is particularly important in fire protection systems, where knowing the status of a valve can be critical for maintaining system integrity and ensuring proper operation in an emergency.

Indicating valves typically have a visible pointer or an indicator that moves with the valve stem. When the valve is fully open, the indicator shows one position (often green or "open"), and when the valve is closed, it shifts to reflect that status (often red or "closed"). This feature allows firefighters or maintenance personnel to quickly assess whether a valve is in the correct position without needing to manually operate or check the valve itself.

In contrast, check valves are designed to prevent backflow and do not provide an indication of their open or closed status, pressure relief valves function to release excess pressure without an indication of their position, and flow control valves regulate the amount of fluid that passes through them, but they too do not typically provide visual indicators of their status. This differentiates the indicating valve as uniquely suited for clear status communication in fire protection applications.