What is the purpose of the King valve in an ammonia refrigeration system?

The King valve plays a critical role in an ammonia refrigeration system as a stop valve, typically located at the outlet of the high-pressure liquid receiver. This means it can be used to isolate the high-pressure liquid refrigerant from the rest of the system when maintenance is needed or during particular operational scenarios.

By using the King valve to control the flow of refrigerant, operators can prevent potential leaks or other hazards during maintenance. This also helps in switching between different components of the system, providing operators the ability to manage refrigerant flow with ease and safety. The design allows for a practical way to handle the high-pressure liquid refrigerant and ensures that the system operates efficiently without unnecessary exposure to pressure fluctuations.

The other options presented do not accurately represent the function of the King valve. While flow regulation, pressure relief, and metering are important functions in refrigeration systems, these roles are typically managed by different components, such as expansion valves and safety relief valves. The distinguishing feature of the King valve is its role in isolating sections of the system for safe operation and maintenance.