Compressor free air delivery, usually abbreviated FAD, describes delivered air on a stated free-air reference basis. Keep that basis and the rated delivery pressure with the flow figure. For an aluminum-saw workshop, a headline airflow number is not a complete supply assessment.
Read compressor capacity separately from the saw’s documented demand. This guide explains the quotation terms and one simple unit conversion. Compressor selection, distribution design and installation remain the responsible site team’s application review.
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What compressor free air delivery means
Atlas Copco’s flow explanation describes delivered air expressed as an equivalent volume at compressor inlet, or free-air, conditions. It distinguishes air leaving the compressor from intake air and notes that internal leakage can make the two quantities different.
The reference basis is essential. Ask the supplier to state the inlet or reference pressure, temperature and humidity used for the quoted capacity. Retain the exact designation rather than substituting an assumed definition of “standard air.”
The discharge pressure is a separate part of the operating point. Request the capacity at the pressure relevant to the site review, with its pressure convention identified. A maximum-flow claim without that information leaves the comparison incomplete.
Do not read FAD as the geometric volume of air moving through the compressed delivery pipe under its local conditions. Likewise, a normal-volume flow uses its defined reference conditions. Have the supplier identify the bases before those values are combined.
Read intake displacement separately
Atlas Copco’s oil-free-compressor selection article warns that intake displacement does not necessarily represent usable air reaching the application. It recommends a delivered-air figure at the required working pressure for the capacity comparison.
If a quotation says only “displacement,” preserve that label. Ask for the manufacturer’s definition and the corresponding delivered-capacity data. Do not rename the number FAD merely because its units resemble another quotation.
Also keep motor power and receiver volume in separate fields. A kilowatt entry describes a power quantity. A receiver-volume entry describes storage. Neither is a complete statement of delivered airflow at the required operating point.
When an offer includes several pressure ratings, identify the capacity entry that belongs with each rating. Do not pair a favorable flow from one condition with a pressure from another. Ask for a complete table or current performance document if the offer is unclear.
Convert the units, keep the reference basis
Consider an invented delivered-flow entry of 12 liters per second. Assume its complete reference and operating conditions are already written on the fictional sheet. The following conversion changes units only.
There are 60 seconds in one minute. Therefore, 12 L/s × 60 = 720 L/min. There are 1,000 liters in one cubic meter, so the same entry is 0.720 m³/min. The three expressions describe the same volume rate on the unchanged stated basis.
| Unit expression | Same stated flow |
|---|---|
| Liters per second | 12 L/s |
| Liters per minute | 720 L/min |
| Cubic meters per minute | 0.720 m³/min |
This arithmetic is not a conversion between compressed outlet volume and free-air volume. It is also not a change from one temperature, pressure or humidity reference to another. Those are different calculations requiring the relevant conditions.
Retain the quantity name beside the converted number. If the original value is FAD, the conversion does not become an intake-displacement figure or a measured flow at the saw. The new notation carries the original scope.
Compare two fictional quotation entries
Imagine Offer A lists “900 L/min intake displacement” with no delivered-capacity statement. Offer B lists “12 L/s FAD” with an identified pressure and reference basis. These are invented document entries, not actual compressor ratings or JiurunCut requirements.
Offer B’s flow can be written as 720 L/min on its stated basis. That conversion does not make A’s 900 L/min a directly comparable delivered-flow value. A larger number has not yet established greater useful capacity.
Ask supplier A to provide its delivered-capacity figure under the conditions needed for the comparison. Ask supplier B to confirm the configuration and performance-document revision. Keep unresolved conditions visible until both entries describe comparable operating points.
Even then, neither entry alone sizes the workshop system. The responsible team still needs the saw’s demand, concurrent users and the actual installation scope. The fictional example demonstrates a document mismatch rather than selecting a compressor.
Check the performance document and its scope
CAGI describes standardized compressor data sheets as a common presentation of performance information. Its performance-verification program independently checks participating manufacturers’ published claims within the program’s stated equipment scope.
Request the current document for the proposed compressor model and package. Read the conditions, test basis and capacity designation with the headline numbers. A sheet for a similar motor size is not the record for the offered item.
If a quotation claims participation in a verification program, check the applicable participant and model documentation. Retain the relevant scope. Do not treat an unrelated certification logo as proof of the complete compressed-air installation.
A performance document describes the assessed compressor or package. Keep that evidence separate from the site supply check at the machine connection. The two records concern different boundaries and may require different verification.
Connect capacity to the documented site demand
Request the utility schedule for the exact saw configuration and options. Identify its flow or consumption basis and defined operating sequence. Our aluminum saw compressed-air guide explains that machine-side requirement.
Give the responsible site team the other connected equipment and the intended use pattern. Keep simultaneous demand and the required working conditions visible. A single machine’s average quantity does not describe the entire workshop.
Ask how the proposed compressor, treatment and distribution scope will be assessed together. This article does not provide a sizing margin, pipe diameter, receiver size or pressure adjustment. Obtain the approved design and configuration-specific installation documents.
Keep air quantity and air quality separately specified. A capacity entry does not close the required particle, water or oil criteria. The selected quality requirements and verification belong to the actual equipment and site plan.
Record the complete supplied package
Identify whether the compressor quotation includes the specified treatment, receiver and connection equipment. Record exclusions and the installation responsibility. The same capacity label can appear on offers with different supplied scopes.
Keep the compressor proposal connected to the machine configuration record. A control description or component photograph does not establish which utilities the complete ordered system needs.
Send JiurunCut your aluminum section and representative cutting job. Request the confirmed machine utility requirements and included options. Have the site and compressor providers review supply suitability against those documented requirements.
Buyer questions
Is intake displacement the same as FAD?
Keep their stated definitions separate. Request delivered-capacity data instead of changing the label on an intake-displacement number.
Does a larger receiver mean more delivered airflow?
Receiver volume and delivered flow are different quantities. Review the actual capacity and application rather than ranking offers by tank volume.
Does converting L/s to L/min change the air conditions?
No. The unit conversion leaves the original reference and operating basis unchanged. A condition conversion needs separate information.
Primary reference scope
Atlas Copco’s flow terminology, delivered-capacity selection explanation and CAGI’s performance-verification overview supply the background. The numbers and offers in this guide are original teaching examples.