What is the primary purpose of a non-return stop valve in a steam system?

The primary purpose of a non-return stop valve in a steam system is to isolate the boiler from downstream equipment. This valve is designed to prevent backflow, ensuring that steam can only flow in one direction—from the boiler to the system—while also allowing for safe maintenance or operation of the downstream components without affecting the boiler. By providing a means to isolate the boiler, it protects the system from potential damage due to reverse flow and prevents issues related to pressure fluctuations.

Understanding this function is crucial for maintaining the safety and efficiency of steam operations, as it ensures that any disturbances in the downstream system do not impact the boiler or create unsafe conditions. It's also important to recognize that while isolating the boiler is essential, the other options do not align with the primary function of the non-return stop valve; they refer to different aspects or functions within a steam system.