Compressed Air Pipe Sizing Chart
Sizing compressed air piping by flow, pressure, length, and allowable pressure drop. The capacity per pipe size depends heavily on the pressure drop you design to, so the SCFM values are approximate starting points — the reliable rule is to keep the drop low and oversize when in doubt. One hard safety rule: never use PVC for compressed air.
Approximate SCFM by pipe size
| Pipe size | Approx SCFM |
|---|---|
| 1/2" | ~10 |
| 3/4" | ~20–40 |
| 1" | ~40–80 |
| 1-1/4" | ~50–100 |
| 1-1/2" | ~75–150 |
| 2" | ~150–350 |
| 3" | ~350–700 |
Velocity limits
| Location | Max velocity |
|---|---|
| Compressor room / main headers | ~20 ft/s |
| Plant distribution mains & branches | ~30 ft/s |
| Absolute maximum (drops to machinery) | ~40 ft/s |
Design for pressure drop, not just flow
A compressed air system lives or dies on pressure drop, because unlike water, the air is expensive to make — every psi lost in the piping is a psi the compressor had to generate and then throw away. That is why sizing is driven by the allowable drop, and why the capacity for a given pipe size is a range rather than a number: design to a tight 1 psi drop and a 1-inch line carries less air; accept 3 psi and the same line carries far more, at the cost of energy. The practical answers:
- Keep total pressure drop from the compressor to the farthest point low — ≤1 psi is the conservative target, ~2–3 psi (≈10%) the acceptable maximum.
- A loop (ring-main) layout feeds demand from two directions, cutting pressure drop and roughly adding half again to effective capacity versus a dead-end run.
- Use steel, copper, aluminum, or stainless — never PVC, which can shatter under pressure. Traditional black iron corrodes internally and is discouraged for new work.
Common questions
How do you size compressed air pipe?
By the flow (SCFM), the operating pressure, the length of the run, and the allowable pressure drop — not by flow alone. The conservative target is to lose no more than about 1 psi from the compressor to the farthest point, with roughly 3 psi (about 10% of a 100 psi line) as the acceptable maximum. Capacity per pipe size can swing 2–3× depending on which drop you design to, so the size chart is a starting point.
Can you use PVC for compressed air?
No — never. PVC becomes brittle over time from heat and compressor oils and can shatter catastrophically under pressure, throwing sharp fragments. It is a genuine safety hazard, not a preference. Use steel, copper, aluminum, or stainless; traditional black iron works but corrodes internally and is discouraged for new installs.
Should I oversize compressed air pipe?
Generally yes. Pressure drop is a permanent energy cost — every 2 psi of drop adds roughly 1% to the compressor’s energy use for the life of the system — so going up a pipe size pays back. A loop (ring-main) layout helps too, feeding demand from two directions to cut the drop and add about half again to effective capacity.
RUN THE NUMBERS
Run your whole job on the same numbers
These NORDIX tools are a taste of the full platform — bid pipeline, estimating, and job costing that carry your numbers from the first bid to the final invoice. Our team sets it up for your shop and walks you through your next real job.
Request access →