Compressed Air Receiver Tank Size Calculator
Size a compressed air receiver tank to cover peak demand during a pressure drop: V = t × Q × Pa ÷ (P1 − P2), the next standard tank, how long it lasts and the rule-of-thumb sizes for your compressor.
How it works
V = t × Q × Pa ÷ (P₁ − P₂) (t in minutes, Q free-air flow, Pa atmospheric pressure, P₁ − P₂ allowed pressure drop; US: gal = 7.48 × ft³) · duration = V × (P₁ − P₂) ÷ (Pa × Q) · rules of thumb: 1 gal/cfm (fixed speed), 3–5 gal/cfm (load/unload rotary screw)
An air receiver stores compressed air so short peaks can be met without starting another compressor and so the pressure stays stable. The air it can release equals its volume times the allowed pressure drop divided by atmospheric pressure (Boyle’s law, isothermal), which gives the drawdown sizing formula used by the Compressed Air Challenge and compressor manufacturers. Separately, load/unload screw compressors need storage to avoid short cycling — commonly 3–5 gallons per cfm of compressor capacity — while variable-speed units need less. Pressure vessels must carry a code stamp (ASME, PED) rated above the compressor’s maximum pressure.
Worked example
To supply an extra 2 m³/min for 1 minute while the pressure falls from 8 to 6 bar, the receiver must hold 1 × 2 × 1.01325 ÷ 2 = 1.013 m³, i.e. 1,013 L. The next standard tank is 1,500 L, which covers that peak for 1.48 minutes. For a 5 m³/min compressor the rules of thumb suggest 668 L (1 gal per cfm) or 2,674 L for a load/unload screw compressor.
Sources: Compressed Air Challenge — Best Practices for Compressed Air Systems (storage sizing) · US DOE — Improving Compressed Air System Performance: A Sourcebook for Industry
Frequently asked questions
How do I size an air receiver tank?
Use V = t × Q × Pa ÷ (P₁ − P₂): the minutes of peak demand times the extra flow, times atmospheric pressure, divided by the pressure drop you can accept. In US units, gallons = 7.48 × minutes × cfm × 14.7 ÷ psi drop.
What is the rule of thumb for receiver size?
About 1 gallon per cfm (134 L per m³/min) for reciprocating and variable-speed compressors, and 3–5 gallons per cfm for load/unload rotary screw compressors to keep cycle times reasonable.
Is a bigger tank always better?
Storage smooths peaks and reduces compressor cycling, but it cannot make up for a compressor that is too small on average. The tank also takes longer to fill at start-up.
Wet or dry receiver — where should it go?
A wet receiver right after the compressor cools the air and drops out water before the dryer; a dry receiver after the dryer supplies peaks with clean dry air. Many plants use both.
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This calculator is for educational purposes. Double-check important results before acting on them.