What component indicates an element change is needed in dry air systems?

The correct answer pertains to the function of telltale oil filters in dry air systems. These filters are designed to indicate when there is a need for maintenance or a change in elements within the system. When the telltale shows signs of blockage or requires servicing, it serves as a clear sign to the operator that the oil or its filtering components are deteriorating, which can affect system performance.

In the context of dry air systems, maintaining optimal performance is essential, and a well-functioning telltale oil filter can prevent potential issues by signaling when intervention is necessary. This proactive approach helps ensure that the system operates efficiently, preventing damage that could result from prolonged neglect.

The other components mentioned each serve different purposes, such as measuring pressure or temperature, but they do not specifically indicate when an element change is required in the same way that telltale oil filters do. Thus, the telltale oil filters are specifically vital for monitoring the quality and effectiveness of the oils used, making them crucial for identifying when a change is warranted.