Which of the following is true about pressure controllers?

Pressure controllers are crucial components in refrigeration systems, serving to regulate and maintain appropriate pressure levels to ensure operational efficiency and safety. The correct choice reflects that pressure controllers can indeed be classified into high and low pressure categories.

This classification helps in understanding their application within different parts of a system, where high pressure could be related to the refrigerant in the condenser section, while low pressure pertains to the evaporator. Recognizing the distinction between high and low pressure controllers allows technicians to select the right device for specific needs, ensuring that the system operates within designed pressure limits.

The other options do not accurately represent the capabilities of pressure controllers. For instance, stating that they can only measure high pressure systems overlooks the fact that low pressure controllers are equally common and necessary in many applications. Similarly, the assertion that they are exclusively digital devices dismisses the variety of pressure controllers, which can also be mechanical. Finally, stating that they only control temperature would misinterpret their fundamental function; pressure controllers primarily manage pressure and may assist indirectly in maintaining temperature through the refrigeration cycle but are not solely focused on temperature control.