What are the two most common methods of compressor cleaning?

• A. Fluid wash and an abrasive grit blast
• B. Water wash and chemical wash
• C. Ultrasonic cleaning and cryogenic cleaning
• D. Oil flush and varnish removal

Answer: (A)

Cleaning a compressor during overhaul aims to remove varnish, oil films, and carbon so airflow and cooling surfaces perform like new. The two most common methods are fluid wash and abrasive grit blast.

Fluid wash uses liquids—solvent or detergent solutions—to dissolve and rinse away deposits. It’s effective for removing varnish, oil residues, and light carbon without aggressive contact, and when done with the right cleaners and temperatures, it can reach complex passages and internal passages that mechanical cleaning alone might miss.

Abrasive grit blast relies on a controlled stream of abrasive media to physically strip away heavy deposits, scale, and old coatings. It’s fast and thorough for stubborn buildup and also leaves a clean, slightly roughened surface that helps any coatings or inspections that follow. It does require careful masking and process control to protect tight tolerances and delicate features.

Other methods exist, but fluid wash covers routine solvent- or detergent-based cleaning, and grit blast handles heavier cleaning and surface prep, making them the standard pairing in most overhaul environments.