What is one way to check a watertight closure for pressure/vacuum?

To effectively check a watertight closure for pressure or vacuum, inspecting for visible leaks is a crucial method. This process involves carefully examining the closure for any signs of fluid intrusion or external air entering, which would indicate a failure in the watertight integrity. Checking for visible leaks can often provide immediate evidence of any breaches, helping to assess the closure's performance under pressure or vacuum conditions.

While the other methods listed, such as applying a pressure gauge or checking the sealing mechanism, can be valuable in a broader context of maintenance and testing, the direct observation of leaks is a straightforward and effective means of determining the reliability of a watertight closure. It allows operators to detect issues that could compromise safety and operational efficacy.

Using these methods together, rather than relying on just one, can ensure a comprehensive evaluation of the watertight integrity and performance of closures as part of good damage control practices.