Compressed Air Resources
Engineering reference tables and tools for compressed air system design, pipe sizing, and pressure drop analysis.
Pipe Sizing & Flow Capacity Reference
Proper pipe sizing is critical to compressed air system efficiency. Undersized piping causes excessive pressure drop, forcing compressors to work harder and wasting energy. The reference table below calculates the maximum recommended airflow (SCFM) for each Schedule 40 steel pipe size based on your acceptable pressure drop per 100 feet of piping. Industry best practice recommends keeping header pressure drop below 1 PSI per 100 feet, with total system drop under 3 PSI from compressor discharge to the point of use.
Adjust the pressure drop input below to see how flow capacity changes across pipe sizes from ½″ single-tool drops up to 12″ large plant mains. Use these values alongside the Sizing Tool for complete system design calculations including fittings, branch take-offs, and dryer losses.
Maximum Recommended Flow by Pipe Size
Schedule 40 steel pipe at 100 PSIG. Flow is calculated as a function of acceptable pressure drop per 100 feet of pipe using the empirical formula ΔP = C × L × Q1.85 / (d5 × P).
Industry guideline: ≤1 PSI drop per 100 ft for headers, ≤3 PSI total system drop.
| Nominal Pipe Size | Inside Dia. (in) | Max Flow @ 1 PSI drop (SCFM) | Typical Application |
|---|---|---|---|
| ½" | 0.622 | 17 | Single tool drop |
| ¾" | 0.824 | 35 | Point-of-use branch |
| 1" | 1.049 | 68 | Small branch line |
| 1¼" | 1.38 | 142 | Branch line |
| 1½" | 1.61 | 216 | Branch / sub-header |
| 2" | 2.067 | 424 | Sub-header |
| 2½" | 2.469 | 686 | Small header |
| 3" | 3.068 | 1,233 | Header (50–150 HP) |
| 4" | 4.026 | 2,571 | Header (150–400 HP) |
| 6" | 6.065 | 7,782 | Header (400–1,000 HP) |
| 8" | 7.981 | 16,342 | Main header (1,000+ HP) |
| 10" | 10.02 | 30,224 | Large plant main |
| 12" | 11.938 | 48,521 | Very large plant main |
Flow values calculated at 100 PSIG, sea level (14.7 PSIA atmospheric), per 100 ft of Schedule 40 steel pipe. Actual pressure drop varies with fittings, bends, and system conditions. Use the Sizing Tool for detailed system calculations.