Which type of valve is permissible between a boiler and a water column?

The use of outside screw and yoke or lever lifting type gate valves between a boiler and a water column is ideal due to their specific design characteristics that ensure reliability and safety in high-pressure environments.

These valves are designed to provide a tight seal when closed, minimizing the risk of leaks that could be dangerous in a boiler system. The outside screw mechanism allows for easy operation and provides a visual confirmation of whether the valve is open or closed. Additionally, their robust construction can withstand the temperature and pressure fluctuations typically occurring in boiler systems.

Due to these advantages, outside screw and yoke or lever lifting type gate valves are the preferred choice in this application, as they enhance safety and operational efficiency. Other types of valves, while useful in different applications, may not meet the stringent requirements needed for use in this critical location.