What are the two basic types of relieve valves used in refrigeration systems?

The correct choice identifies the two fundamental types of relieve valves used in refrigeration systems as automatic relief valves and one-time relief valves. Automatic relief valves are designed to respond to excessive pressure within a system, functioning continuously to release pressure and maintain safety by preventing potential over-pressurization. These valves activate based on pressure changes, making them reliable for ongoing system operation.

On the other hand, one-time relief valves are typically used in applications where a single discharge is needed, usually in situations where a specific circumstance, such as an emergency or certain maintenance operations, requires the system to relieve pressure just once. This type of valve is crucial for situations where transient conditions might lead to dangerous pressure levels, providing a safety mechanism during those specific instances.

Understanding these types of relief valves is essential for ensuring the safe operation of refrigeration systems, as they play a critical role in managing pressure and protecting equipment from potential failures. The other options may describe types of valves or functions that are not standard classifications for refrigeration systems' relieve valves, making them less applicable in this context.