What factors determine compressor type selection?

Compressor selection factors: Flow rate - centrifugal for high flow (>1000 cfm), reciprocating for low flow; positive displacement for accurate metering. Pressure ratio - single stage centrifugal up to 3:1, reciprocating handles higher ratios. Gas properties - molecular weight affects centrifugal head, corrosive gases need special materials or diaphragm type. Efficiency requirements - centrifugal 70-80%, reciprocating 75-90% at design point. Turndown - centrifugal limited to 70% (surge), reciprocating more flexible. Reliability - centrifugal fewer moving parts, reciprocating needs more maintenance. Other factors: driver availability, space, noise, pulsation dampening needs. Detailed selection involves head/flow calculations and vendor curves.