Which type of test examines the tightness of the pump, including its valves and fittings?

The correct answer is a vacuum test, which is a method used to assess the tightness and integrity of a pump, valves, and fittings. This testing process involves creating a vacuum inside the pump system and monitoring for any loss of vacuum, which would indicate leaks. The vacuum test is particularly effective in identifying small leaks that could compromise the performance and reliability of the pump system.

In contrast, other testing methods have different focuses. A pressure test typically involves applying pressure to test for leaks, while a flow test measures the actual output of the pump in terms of flow rate and pressure under operational conditions. A hydrostatic test, on the other hand, involves filling the system with water and pressurizing it to examine for leaks, but it does not assess the tightness in the same specific manner as a vacuum test. Each of these tests serves an important role in the overall maintenance and assurance of pump functionality, but the vacuum test is specifically designed to evaluate tightness, making it the correct choice for this question.