Refrigeration valves, specifically the suction valve and discharge valve, prevent liquid refrigerant from entering the compressor by their design and location within the refrigeration system.

1. Suction Valve: The suction valve is located at the inlet of the compressor. It is designed to only allow refrigerant in gaseous state to enter the compressor while preventing any liquid refrigerant from passing through. This valve is usually a reed or plate-type valve that opens and closes based on the pressure difference between the evaporator (low pressure) and the compressor (higher pressure). When the compressor operates, it creates a pressure drop at the suction side, which helps in drawing in gaseous refrigerant and prevents liquid refrigerant from entering the compressor.

2. Discharge Valve: The discharge valve is located at the outlet of the compressor. It is designed to facilitate the flow of the compressed refrigerant gas out of the compressor and into the condensing unit. This valve is designed to be unidirectional, allowing the flow of gas only in one direction, preventing any backflow of refrigerant into the compressor. While its primary function is not to prevent liquid refrigerant from entering the compressor, it indirectly assists in maintaining the integrity of the system by ensuring that only gas is expelled from the compressor.

In addition to the valves, other components and features within the refrigeration system also play a role in preventing the liquid refrigerant from entering the compressor. These include the suction line and pipework, which are designed to promote the proper vaporization of refrigerant before reaching the compressor, and the proper sizing and control of the expansion device, which regulates the flow of refrigerant into the evaporator.

Overall, the combination of the suction valve, discharge valve, proper piping, and system design helps prevent liquid refrigerant from reaching the compressor, as it can cause damage to the compressor and reduce its efficiency.