Which of the following environmental conditions must be recorded before and after pump performance testing?

The correct choice involves recognizing the significant impact that humidity has on pump performance testing. When testing a pump, humidity is a crucial environmental condition to monitor, as it affects the air density and can influence the performance of water movements and the efficiency of the pump itself.

Humidity levels can change the viscosity of fluids and alter the way that air interacts with the fluid being pumped, potentially skewing the results of the test if not recorded. High humidity may lead to condensation that can introduce water into components where it is not desired, affecting overall performance and longevity.

While temperature is also significant — affecting fluid properties and energy efficiency during testing — humidity provides a different context specifically relevant to how the pump functions in various atmospheric conditions. Wind speed and rainfall, while environmental factors, do not have the direct impact on pump performance testing in the same way humidity does, particularly in controlled testing environments. Thus, focusing on humidity offers valuable insights into the pump’s operational capabilities under testing conditions.