AMCA 210 defines the laboratory method for measuring fan performance, so a centrifugal fan's published airflow, pressure, power, and efficiency are comparable across manufacturers.
What AMCA 210 Standardizes
Without a standard, every factory could test a fan at a convenient inlet condition and publish flattering numbers. AMCA 210 (with its international sibling ISO 5801) fixes the duct arrangements, the instrument locations, the units, and the correction back to standard air density. The result is a certified performance curve, not a marketing curve. A buyer comparing two 4-72 type centrifugal fans can trust that both were measured the same way, which is the foundation of fair equipment selection.
The standard covers both inlet and outlet ducted arrangements and specifies how to correct for air density when the test is not at standard conditions (20°C, 1,013 mbar, 50% RH). At altitude or high temperature the density correction can shift the effective pressure by several percent, and ignoring it is a common source of a fan that "tests fine in the lab but won't make pressure on site."
There is a second, less obvious reason the method matters: laboratory conditions are deliberately ideal. The test duct gives the impeller a uniform, swirl-free approach that almost no plant room reproduces. On site an elbow close to the inlet, a badly proportioned inlet box, or a bend immediately after the outlet introduces what the industry calls system effect, and the penalty is real: a poor inlet condition can cost 5 to 15% of the pressure the fan made in the laboratory. The tested curve is therefore the fan's honest capability, and the designer's job is to avoid throwing that capability away in the ductwork. A curve is a promise about the fan, not about the installation.
Test Setup and Measurements
The fan is mounted in a calibrated duct with flow nozzles or a pitot traverse, a driven motor on a torque meter, and pressure taps at defined planes. Volume flow, total or static pressure, shaft power, and speed are recorded across a sweep of operating points, then the lab builds the characteristic curve and applies the AMCA fan efficiency definitions so the numbers mean the same thing for every supplier.
| Item | Specification | Note |
|---|---|---|
| Standard | AMCA 210 / ISO 5801 | Laboratory rating method |
| Flow measurement | Nozzle or pitot | Calibrated traverse plane |
| Pressure | 0–3,000 Pa | Static or total per arrangement |
| Speed | ± 0.5% | Encoder or strobe |
| Density correction | To standard air | 20°C, 1,013 mbar |
| Inlet system effect | 5–15% pressure loss | Poor approach conditions on site |
| Flow measurement accuracy | Typically ± 2% | Calibrated nozzle chamber |
From the raw points the lab builds the characteristic curve, then applies the AMCA fan efficiency definitions. Static efficiency, not total, is the figure most relevant when the fan feeds a duct system with losses, because the system cares about usable static pressure, not the velocity energy still in the leaving jet.
A tested curve carries more than one line. Alongside pressure against volume it usually shows shaft power, static efficiency, and sometimes sound power, all at a stated speed and density. Because the fan laws let a curve be scaled, a family of speeds can be derived from one measured set: flow varies with speed, pressure with the square, and power with the cube, so a 10% speed reduction cuts absorbed power by roughly 27%. That relationship underpins every variable-speed energy calculation in a building, and it only holds if the base curve was honestly measured. Tolerance grades within the standard also define how far a delivered unit may deviate, which is what a specification should reference.
Reading a Tested Curve
- Find the duty point: Cross the required flow and pressure on the curve, not near it.
- Check the efficiency band: Operate within the flat high-efficiency region, not the steep ends.
- Confirm power at duty: Size the motor from the tested shaft power plus a service factor.
- Ask for the report: A catalog curve without an AMCA 210 reference is unverified.
- Correct for site: Apply density correction for altitude and temperature before ordering.
- Design the inlet: Protect the tested performance by allowing a clean, swirl-free approach to the wheel.
- Scale with the fan laws: Use the flow, square, and cube relationships for speed changes instead of re-guessing the duty.
Why Standard Testing Builds Trust
A fan rated by a recognized method removes the single biggest risk in equipment selection: that the unit cannot meet the specified point. Keruite runs centrifugal fan performance on this method in its own laboratory so the curve shipped with the unit reflects measured data, and the buyer can place the duty point on a curve that was actually generated, not extrapolated.
For a specifier the value of a measured curve is that it shifts risk. An extrapolated catalogue line leaves uncertainty with the buyer; a laboratory point leaves it with the manufacturer. Testing inside an 80,000 m² plant that has produced fans for more than 30 years means the same chamber measures prototype and production units alike, so the curve does not drift as models mature. ISO 9001:2015 process control keeps impeller geometry inside the tolerance the curve assumes, CCC certification covers the electrical build, and exports to more than 50 countries mean curves are issued in both Pa with m³/h and inch-wg with CFM conventions.
Our engineers respond to selection enquiries within 24 hours, including AMCA 210 performance curves and duty-point matching for centrifugal fans.