Minnesota Boiler License Practice Exam 2025 - Free Boiler License Practice Questions and Study Guide

In an automatic non-return valve, the valve stem is typically not connected to the disc. This design allows the disc to move freely in response to the flow of fluid, permitting it to open when fluid is moving in the correct direction and close against backflow. The separate movement ensures that pressure changes do not inadvertently transmit to the stem, which is crucial for the valve's operation and function.

The automatic non-return mechanism relies on the weight or spring action of the disc rather than a direct mechanical connection to the stem, allowing for independent operation. This feature prevents the risk of the valve opening unintentionally due to pressure fluctuations or changes in flow direction, thus maintaining system integrity and preventing backflow.

Understanding this mechanism is crucial for ensuring proper maintenance and operational efficiency when working with such valves in boiler systems.