A. water-lubricated
B. oil lubrication
C. no lubrication
D. Lubrication with special lubricants
Answer: D
Analysis: Oil-free air compressors usually use special lubricants to cool and lubricate parts to ensure the purity of the compressed air.
A. General Certification B. Medical certification C. Industrial certification D. No certification required answer: B. Medical certification
A. 1-2% B. 3-5% C. 6-8% D. 10-15% Answer: B Analysis: High humidity reduces effective air volume by 3-5%.
A. Higher B. Lower C. Same as oil injection air compressor D. The answer cannot be determined: A Analysis: The manufacturing cost of oil-free air compressors is usually high, and the initial investment is large, but the long-term maintenance cost is low.
A. Portable air compressor B. Industrial air compressor C. Medical air compressor D. Mine air compressor Answer: A. portable air compressor
A. Home use B. Commercial places use C. D. Agricultural production use answer: C. Industrial use