First, follow the standard operating procedures for shutting down the oil-free air compressor; the normal shutdown sequence is the reverse of the startup sequence. Simply reduce the rotational speed gradually to a very low level. Fully open the discharge bypass valve, fully close the main discharge valve, shut down the drive motor, and verify that the entire air compressor unit gradually comes to a complete stop automatically. Do not cut off the cooling water supply within 30 minutes after the equipment has stopped.
Next, after completing operations, inspect the components at each stage, specifically checking the fit between the piston rings and the cylinder walls. If any cracks are found in the piston rings, replace them with spare parts. Inspect the front cylinder covers and the cylinder bore surfaces; if friction marks are visible, identify the cause. Check the friction surfaces of the crosshead slide and the frame guide rails. Remove the connecting rod big-end bushings and crosshead pins to inspect the friction surfaces for wear.
It is also necessary to verify that the oil level indicated by the gauge meets requirements and to check the security of all connections and fasteners; tighten any loose parts immediately. Observe the moving parts to ensure they operate smoothly; manually rotate the flywheel to cycle the compressor two or three times, checking for any binding or collisions.
Finally, monitor the quality of the lubricating oil and change the oil in the crankcase. After the initial run, fine metal particles accumulate in the oil due to the break-in of parts and the cleaning action of the lubricant; therefore, the oil must be changed after the first 24 hours of operation. Change the oil again after 200 hours of operation. Following these two initial changes, adhere to the standard maintenance schedule for subsequent oil changes.
