New York Low Pressure Boiler COF Practice

How many complete turns does a slow opening valve require to go from full close to full open?

1. 3 turns

2. 5 turns

3. 7 turns

4. 10 turns

The correct answer is: 5 turns

A slow opening valve is designed to control the flow of fluid in a system more gradually than a quick-opening valve. The typical design of a slow-opening valve usually requires several complete turns of the handle to move from the fully closed position to the fully opened position. In this case, five complete turns is generally recognized as the standard for many slow-opening valves. This gradual adjustment allows for careful control over the flow rate, which is essential for systems that need precise flow regulation, such as in heating systems or process piping. A slow opening helps prevent water hammer and sudden changes in pressure that could be detrimental to the system. Valves that require only three or particularly larger numbers such as seven or ten turns are less common for slow-opening applications. This standard not only helps in operational consistency but also ensures that operators are familiar with valve control intervals. Understanding the requirements for slow-opening valves is crucial for maintaining safety and efficiency in boiler operations and related systems.