Same-reference arithmetic only
Compressed-Air Flow Aggregation
Sum explicit end-use free-air flows on one declared reference basis. The duty-weighted value is a time-average estimate; the all-listed sum is a simple coincidence envelope. Neither is a compressor-sizing verdict.
Flow arithmetic
Two different sums
The first is an arithmetic time average if each duty fraction is valid over the same interval. It loses event timing and cannot predict a peak. The second assumes every listed source flow occurs together; it is not a statistical diversity calculation. Purge, drains, artificial demand and other losses must be explicit rows or otherwise measured.
FAD and reference conditions
ISO 1217:2009 with Amendment 1:2016 is the published displacement-compressor acceptance-test standard for volume flow and power, confirmed in 2021 and now under revision. A compressor’s stated performance must be compared on its applicable test/reference basis; this page does not reproduce the standard or certify FAD.
Den CAGI Compressed Air System Design guide stresses that end-use and compressor capacity are commonly stated as free-air volume and that demand dynamics, storage and capacity control are central to design. The US DOE compressed-air evaluation protocol develops load profiles from measurements and quantifies leakage separately.
Not compressor sizing: verify measured time-resolved demand/peaks, required pressure at each point after losses, air quality/dryers and purge, receiver/header storage, compressor control and turndown, unloaded energy, duty rating, ambient/altitude, redundancy, future change, leakage program and manufacturer performance at the same reference conditions.
