Which safety device prevents excessive pressure buildup in a refrigerating system?

The pressure relief valve is the safety device that prevents excessive pressure buildup in a refrigerating system. Its primary function is to release excess pressure that may occur due to various factors such as high temperatures or malfunctioning components. This is crucial for protecting the system from damage, ensuring safe operation, and preventing potential hazards such as leaks or explosions.

In a refrigerating system, maintaining proper pressure levels is essential for efficient operation. If pressure exceeds safe limits, the pressure relief valve automatically opens to allow some of the refrigerant to escape, thereby relieving the pressure. This mechanism is vital, especially in systems where the pressurization could lead to critical failures.

Other components mentioned, like the thermostatic expansion valve and capillary tube, serve important roles in controlling refrigerant flow and system efficiency but do not specifically function as safety devices for pressure relief. A sight glass is used to observe the refrigerant flow and level, but it does not contribute to pressure regulation. Thus, the pressure relief valve is the key safety feature in this context, making it the appropriate choice for preventing excessive pressure buildup.