An operating SSTG must be secured when vacuum decreases to how many inches?

When operating a Ship Service Turbine Generator (SSTG), it is crucial to maintain a certain vacuum level to ensure efficient performance and prevent damage to the system. The vacuum level is measured in inches of mercury (inHg), and a decrease in this vacuum can indicate a potential issue.

The correct answer of 15 inches is critical because it reflects the operational guidelines established for maintaining optimal conditions in the SSTG. If the vacuum level drops to 15 inches or below, it signals that the system may not be able to operate effectively, which could lead to overheating, reduced efficiency, or even mechanical failure. Therefore, securing the SSTG at this threshold is a preventive measure to ensure the reliability and safety of the equipment.

Understanding the significance of maintaining proper vacuum levels is essential for machinists and engineers. Each operational standard, like the 15 inches guideline, plays a vital role in the overall performance and longevity of marine equipment. By securing the SSTG when vacuum levels drop to this point, personnel can mitigate risks and ensure a steady operation.