Six compressor types, one decision. What's the duty cycle, what does the air touch, where does the unit live, and how much downtime can the plant absorb? This page walks the spec from "I need a compressor" to the right type, size, and brand tier on the quote — comparison first, decision tree second, questions to ask third.
Rotary Screw Compressor Fixed Speed 
Rotary Screw Compressor Vfd 
Reciprocating Compressor 
Oil Free Compressor 
Portable Contractor Compressor Duplex Triplex Compressor System Tap any type to jump to its page. The Decision Guide further down asks three questions that funnel the spec to one of these.
Six compressor types make the air every other layer is sized, treated, and stored against. Start here or nothing downstream is right.
Intermittent shop work routes to reciprocating or portable; continuous plant duty routes to rotary screw — fixed-speed if steady, VFD if demand swings.
Food, pharma, medical, electronics, fine finishing where air touches product = Class 0 oil-free, full stop. Downstream filtration never substitutes for it at the source.
Undersized starves the plant on every peak; oversized short-cycles and burns power; the wrong type for the duty overheats and dies young.
Size duplex/triplex so one pump out still covers full demand, against a receiver sized on combined output — not nameplate.
Oil, filters, separators, rebuilds — the quote sets both the energy bill and the MRO cadence for the life of the plant. Quote the full stack.
Distributor-facing reading. The trade-off column is the one that closes the loop — every type buys something and gives something up. Knowing what each type costs you is how the right one gets on the quote without a callback.
Reading the brand bench column — the bar shows how many of SPC's tier slots (Industry Leader · Emerging · Economical · adjacent) carry an option at that product type. A deep bench means a price-driven and a spec-driven option both close cleanly; a narrow bench means the available brands map closely to the technical requirements and the comparison stops being a tier choice. Generation has SPC's deepest brand bench in the whole system on the reciprocating and fixed-speed-screw rows; the bench narrows deliberately on oil-free (Class 0 architecture has real engineering content that economical-tier makers don't deliver reliably) and on portable (most contractor portables in the field are Castair-class regardless of badge).
Draw a line from the customer's answer at the top to the type name at the bottom. This is the page distributors screenshot and send to a customer the day before a quote call — so the customer comes prepared with the answers, and the call is about the brand and the budget, not the basics.
If the customer doesn't know the answer to the root question, work it backward from the tool list and the production schedule: "Across an average hour, how many minutes is the compressor actually compressing — not just powered on?" Under ~40 minutes is intermittent (recip or portable). Over ~40 minutes is continuous (rotary screw — fixed-speed or VFD). Oil-free is layered on top regardless: if the air touches food, drug product, medical patients, semiconductor wafers, paint, or breathing air, route to oil-free first and pick the size second. Redundancy is the same overlay logic: if a day's outage scraps a batch or fails a customer contract, duplex / triplex is the right form factor for whichever type the duty cycle picks.
The compressor decision sets the air system. Get it wrong and every other piece of the system gets compromised — get it right and the rest of the layers have a clean foundation to work against.
If the customer answers most of these at the first call, the second call is the quote. If they can't answer any, the compressors are rarely the only spec gap — flag it and push for a site walk.
Generation is the head of the line in any compressed air system — everything downstream is sized, treated, stored, and distributed against whatever the compressor actually produces. Get this layer wrong and there is no fix downstream: an undersized compressor starves the plant on every demand peak; an oversized one short-cycles and burns electricity making air nobody is using; the wrong type for the duty cycle overheats and dies young; the wrong type for the air-quality requirement contaminates product the first shift and fails the audit the next. Generation is also where the recurring service relationship begins — every compressor sold is a seven-to-fifteen-year stream of oil, filters, separators, and rebuilds — so the decision made at the quote sets both the energy bill and the MRO cadence for the life of the plant. Get it right once and the rest of the system has a clean foundation to work against.
The heart of the system — where atmospheric air becomes usable compressed air. Everything downstream is sized, treated, and stored against whatever the compressor produces.
First stage downstream — aftercoolers and water separators pull the bulk water and heat out of the discharge before it ever reaches the dryer. Quote with every rotary-screw install.
→The core of treatment — drops the air's dew point to whatever the end use can tolerate. Refrigerated for indoor general industrial; desiccant for pharma, outdoor, or sub-freezing distribution; deliquescent for off-grid portable.
→Polishes out the remaining oil aerosol, particulate, and (on Class 0 systems) hydrocarbon vapor. Always quoted as a stack — particulate pre-filter → coalescing → carbon if the application needs it.
→Handles the water and oil-water emulsion the compressor and treatment stages pull out. Electronic-timer drains on every drain point; oil-water separator on the discharge — sanitary-sewer dumping of oily condensate is a regulatory violation in most jurisdictions.
→Tell us the end-use, the rough flow, and what climate the unit would sit in. We'll come back with a configured quote — the right type, the right tier, and the upstream gear the warranty assumes.
—. We reply within one business day with pricing, lead-time, and configured parts.