21 CFM Air Compressors for Sale

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Start by totaling the airflow your work requires, then use the 21 cfm air compressor category to filter for units rated at this output. Compare the delivered CFM at your required working PSI on each listing, and size above your calculated demand so the compressor is not running all of the time.

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Checking Air Demand At 21 CFM

Filtering for 21 CFM works best once you have added up what your tasks actually draw. Total the air demand of every tool or job running at the same time, not just the largest single tool, then apply a sizing buffer before comparing that figure against the delivered CFM on each product page. Because a compressor sized right at its rated output has little margin, a single-stage piston compressor should generally deliver about twice the application's required CFM, while a two-stage piston typically needs roughly 25 to 40 percent more. Before choosing, make sure it can handle the load.

Matching Duty Cycle To Airflow At 21 CFM

How often you draw air matters as much as the total figure. Intermittent use, where a tool runs briefly and then rests while the compressor recovers, places a lighter sustained demand than continuous operation does. Sustained draw or running more than one tool at once raises the continuous demand and can push your real requirement past 21 CFM. Total the airflow for everything running at once, apply your buffer, and compare the result against the delivered CFM at your working PSI so the delivered output covers real demand.

FAQ:

Should I compare 21 CFM with the lower or higher linked category?
If your verified demand at working pressure falls below 21 CFM, compare the 20 CFM air compressors page; if your totaled demand or sizing buffer runs higher, step up to the 25 CFM air compressors choices for more delivered airflow.

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21 CFM

Quincy QGS 7.5 TMD-1 7.5 HP 230 Volt Single Phase 60 Gallon Tank Mount Rotary Screw Air Compressor with Dryer

Quincy QGS 7.5 TMD-3 7.5 HP 230/460 Volt Three Phase, 60 Gallon Horizontal Rotary Screw Air Compressor with Dryer

Chicago Pneumatic QRS 7.5 BM-1 7.5 HP Base Mount Rotary 1 Ph

fiac NS 5.5 /270 Silver Series 5.5 HP 208/240 Volt 3 Phase Tank Mount Rotary Screw Air Compressor

fiac NS 5.5 Silver Series 5.5 HP 208/240 Volt 3 Phase Base Mount Rotary Screw Air Compressor

fiac NS D 5.5 /270 Silver Series 5.5 HP 208/240 Volt 3 Phase Tank Mount Rotary Screw Air Compressor with Dryer

Jenny W11HGB-30P 11 HP Honda Gasoline Driven Two Stage 30 Gallon Air Compressor with Wheels

NUAIR MERCURY 7.5-10 M 72G D 7.5 HP 208-230 Volt Single Phase Tank Mount Rotary Screw Air Compressor with Dryer

Quincy QGS 7.5 BM-3 7.5 HP 230/460 Volt Three Phase Base Mount Air Compressor

Quincy QGS 7.5 TM-1 7.5 HP 230 Volt Single Phase, 60 Gallon Horizontal Rotary Screw Air Compressor

Quincy QGS 7.5 TM-3 7.5 HP 230/460 Volt Three Phase, 60 Gallon Horizontal Rotary Screw Air Compressor

Checking Air Demand At 21 CFM

Matching Duty Cycle To Airflow At 21 CFM