How does a hydraulic accumulator prevent air from entering the fluid system?

A hydraulic accumulator operates by storing energy in the form of hydraulic fluid, often utilizing a gas, typically nitrogen, in a separate chamber. The design of the accumulator features a physical separation between the air (or gas) chamber and the fluid chamber. This physical separation is crucial because it prevents the two fluids from mixing, thereby ensuring that air does not enter the hydraulic fluid system.

By maintaining this separation, the accumulator allows the system to function effectively while also mitigating the risk of cavitation, which can negatively affect performance. The non-flexible barrier approach, often represented in certain types of accumulators, is not the predominant way air is prevented from entering. Instead, the use of a gas cushion above the hydraulic fluid keeps pressure regulated and allows for the absorption of shocks or surges in the hydraulic system.

This physical structure effectively isolates air from the hydraulic fluid, thus ensuring the integrity of the hydraulic system and maintaining performance. Hence, the correct answer reflects the fundamental operational principle of hydraulic accumulators in preventing air from contaminating the fluid system.