A method of unloading a reciprocating compressor is to:

Unloading a reciprocating compressor is a critical process often used to reduce the workload by decreasing or preventing the flow of the compressed gas. By holding the inlet valves in the open position, the compressor can draw in the gas without compressing it, effectively unloading it. This method allows the system to maintain operational readiness while preventing the compressor from building up pressure, which could lead to mechanical stress or damage during low-demand periods.

Keeping the inlet valves open allows the compressor to cycle without the gaseous mixture being compressed, providing a balanced approach to managing energy consumption and avoiding operational hazards associated with over-compression. This can be especially useful during startup or when system demand fluctuates.

The other methods, while they may influence the operation of a compressor, do not effectively achieve the unloading goal. For instance, holding the discharge valve closed would prevent any gas from being expelled, potentially leading to dangerous pressure buildup. Likewise, holding the discharge valve open would allow gas to flow back, which may not be sustainable or safe. Installing a check valve would prevent backflow but does not directly influence the compressor's unloading mechanism. Therefore, having the inlet valves open is the most effective method for unloading a reciprocating compressor.