Every refrigerating system must be protected by which of the following?

Every refrigerating system must be protected by a pressure relief device to ensure safe operation. This device plays a critical role in preventing dangerous pressure build-up within the system. If the system experiences a malfunction or blockage, the pressure can rise to unsafe levels, potentially leading to equipment failure or even explosions. The pressure relief device is designed to open at a predetermined pressure, allowing some of the refrigerant to escape safely, thus relieving excess pressure and protecting the integrity of the entire system.

While a temperature gauge, expansion valve, and compressor are also essential components of a refrigerating system, they do not serve the specific safety function that a pressure relief device provides. The temperature gauge monitors system performance, the expansion valve regulates refrigerant flow, and the compressor compresses the refrigerant, but none of these aspects address the critical need for pressure regulation to ensure safety during operation.