Through which valve is the pressurizing gas admitted to the refrigeration system?

The pressurizing gas is admitted to the refrigeration system through the charging valve. This valve is specifically designed for introducing refrigerant into the system, allowing technicians to add refrigerant as needed to maintain the desired pressure and system operations.

The charging valve typically connects to a gauge or charging hose, making it easier for service personnel to monitor the system's refrigerant levels. By using the charging valve, technicians can ensure that the refrigerant is filled to the recommended specifications, which is critical for the efficient operation of the refrigeration system.

The other types of valves serve different functions: discharge valves are used for releasing gas from the compressor, service valves are for maintenance operations like checking system pressures, and liquid line valves control the flow of refrigerant in the liquid line of the system. Each has a distinct role, but the charging valve is uniquely suited for the purpose of introducing refrigerant gas into the system.