A. Screw B. Piston C. Centrifugal wheel D. Scroll disk answer: B. piston
A. Higher B. Lower C. Same as oil injection air compressor D. The answer cannot be determined: B Analysis: Oil-free air compressors do not need to replace lubricants and oil filters, so the maintenance cost is low.
A. Volume efficiency loss B. Air compressor brand premium C. Intake air temperature D. Filter pressure loss answer: B Analysis: Gas production is affected by mechanical efficiency, environmental factors and system matching, and has nothing to do with the brand.
A. Price and brand B. Performance, price and brand C. Market demand and technological development D. Production date and transportation method Answer: C. Market demand and technological development
A. Oil injection air compressor B. Oil-free air compressor C. Both can be D. The answer cannot be determined: A Analysis: Oil injection air compressors have low initial investment and are suitable for companies with limited budgets.