How many complete turns does a slow opening valve require to be fully opened or closed?

A slow opening valve typically requires a specific number of complete turns to achieve full operation, either opened or closed. In this case, five complete turns allows the valve to move through its full range of motion in a controlled manner. This design helps to provide gradual flow adjustments, making it particularly suitable for applications where precise flow control is essential.

The reason five turns is the standard for slow opening valves relates to the mechanics of the valve's internal components. The design ensures a stable and slow adjustment of flow, which helps prevent water hammer and reduces stress on the piping system. Understanding the mechanics behind slow opening valves enhances the ability to select the proper valve for different applications in a piping system.

The other options do not meet this requirement, as three, four, or six turns are either insufficient for the nuanced control required or exceed the standard parameters typically associated with slow opening valves. Hence, five turns is recognized as the correct choice for achieving the full range of motion necessary for effective operation.