Why are low-pressure systems unlikely to have air and moisture enter the system?

Low-pressure systems are designed to operate below atmospheric pressure, which creates conditions that naturally inhibit the ingress of air and moisture. When a system is at a pressure lower than that of the surrounding atmosphere, a pressure differential exists; this means that air and moisture outside the system are less likely to enter since they would have to move against that pressure differential.

The design of low-pressure systems focuses on maintaining this negative pressure to ensure efficiency, prevent contamination, and protect the integrity of the refrigerant cycle. This characteristic is vital for maintaining optimal performance, as the presence of air and moisture can lead to system inefficiencies and potential damage.

While other options might suggest various methods or features that could influence system operations, they do not directly address the impact of operating below atmospheric pressure in preventing air and moisture entry to the same extent.