Air Compressor

Rotary screw compressors use two intermeshing helical rotors to compress air continuously — designed for 100 percent duty cycles, high CFM output, and quiet operation in production environments. Reciprocating piston compressors use pistons driven by a crankshaft and are designed for intermittent duty cycles, typically 50 to 75 percent. Piston compressors are more economical for lower-demand applications; rotary screws are preferred for continuous production shop air demand.

Single-stage piston compressors compress air from atmospheric pressure to tank pressure in one stroke — typically rated to 135 PSI maximum. Two-stage piston compressors compress air in two steps with an intercooler between stages, reaching 175 PSI or higher with greater efficiency at sustained high pressure. Two-stage models are the standard for heavy-duty automotive shop air requiring continuous high-pressure output.

A rough guide: a single-bay shop with basic air tools runs well on 5 to 7.5 HP. A shop with two to three bays running impact wrenches and spray equipment typically needs 10 to 15 HP. High-volume shops with four or more bays should plan for 20 to 30 HP. Total all tools CFM requirements and add 25 percent headroom for demand spikes and future tool additions.

CFM is cubic feet per minute — the volume of air a compressor delivers at a specific PSI. Add the CFM requirements of all tools you may run simultaneously, then add 25 to 30 percent safety margin. Air impact
wrenches typically use 4 to 8 CFM, spray paint guns 10 to 25 CFM, and general blow guns 1 to 5 CFM. Always size to peak simultaneous demand, not average.

Larger tanks reduce compressor cycling frequency — the motor runs less often, extending pump and motor life while handling demand spikes without pressure drop. A 60-gallon tank suits light intermittent demand. An 80-gallon tank is standard for most 2 to 3 bay shops. 120 and 240-gallon tanks are used for high-demand applications or where reduced cycling and longer run intervals are priorities.

Single-phase 115V or 230V is standard in residential and small commercial buildings. Three-phase 208V, 230V, or 460V is available in commercial and industrial facilities and delivers more efficient motor
operation, especially above 5 HP. Three-phase compressors run cooler, last longer, and cost less to operate than single-phase equivalents at the same HP rating.

Yes, for most automotive shop applications. Unprocessed compressed air contains moisture that corrodes air tools, contaminates spray finishes, and damages pneumatic controls. A refrigerated air dryer paired with an aftercooler and coalescing filter is the standard treatment setup for automotive service shops. Alamo Equipment can configure a complete treatment system alongside your compressor purchase.

Alamo Equipment carries Atlas and FS Curtis compressors — two of the most established commercial compressor brands in the U.S. market. Both manufacturers offer a full range of reciprocating piston and rotary screw compressors sized for small shop through large industrial applications, with nationwide service and parts support available.

Follow manufacturer scheduled maintenance intervals — typically oil changes every 500 to 1,000 hours for piston compressors and air/oil separator changes every 2,000 hours for rotary screws. Running hot, increased cycling frequency, reduced CFM output, or unusual noise are signs that service is needed before the next scheduled interval. Alamo Equipment can assist with service planning.