Blower Performance Testing and Guarantees: ISO 5801 and AMCA 210

A blower’s published curve is only as trustworthy as the test behind it. ISO 5801 and AMCA 210 define how flow, pressure, power, and speed are measured in a standardised airway, so ratings from different manufacturers can be compared on the same basis. Knowing what these standards cover, which installation arrangement a curve represents, and how performance should be proved after installation protects you from buying on numbers that will not repeat on site.

What the Standards Cover

ISO 5801, “Fans: Performance testing using standardized airways,” specifies procedures for determining the performance of fans of all types except those designed solely for air circulation, such as ceiling and table fans. Its 2017 edition provides estimates of measurement uncertainty and rules for converting test results for changes in speed, gas handled, and, for model tests, size. AMCA 210 is the equivalent North American standard for laboratory air performance testing, and AMCA accepts testing to either standard equivalently for its efficiency programme. AMCA’s Certified Ratings Program publishes rules for certified air and sound ratings.

A blower is a fan for the purposes of these standards, so they apply to the machines in our range. See blower versus fan.

What a Test Measures

A test sets the blower to a series of flow rates and measures at each one the flow, the fan pressure (static and total), the speed, the input power, and the gas density. From these come the blower curve, the power curve, and the efficiency, corrected to a stated speed and standard air. That is why certified curves are quoted at standard air.

Installation Categories A to D

A blower performs differently depending on what is connected to its inlet and outlet. ISO 5801 defines four installation categories.

Category	Inlet	Outlet	Typical real-world case
A	Free	Free	Blower drawing from and discharging to open space
B	Free	Ducted	Blower drawing from a room and discharging into a duct
C	Ducted	Free	Blower with an inlet duct, discharging into a space
D	Ducted	Ducted	Blower fully connected in a duct system

Most industrial blowers in process duty are installed as category D, ducted at both ends. A curve tested in category A does not automatically apply, because the losses and pressure basis differ. Check that the tested arrangement matches yours.

Testing on Site: ISO 5802

Laboratory standards use idealised airways. On site, bends close to the inlet, uneven velocity profiles, and leakage change performance. ISO 5802 covers performance testing of fans in situ. A site test carries higher uncertainty than a laboratory test, so agree the method, the tolerance, and the acceptance criteria before testing.

Sound and Vibration Testing

Sound power is tested to the ISO 13347 series and AMCA 300, and in-duct sound to ISO 5136. Vibration is checked to ISO 14694 or ISO 20816-3 depending on size. See blower noise and silencers and bearings, balancing and vibration.

Large Blowers and Scaling

Test facilities have size limits, and large blowers may be tested at reduced size or as models and then scaled. ISO 5801 includes rules for conversion, and the scaling assumes geometric similarity and matching system conditions. Ask whether a rating is measured on the actual size or derived from a scaled test, and what tolerance applies.

Hot Gas and Testing

Blowers are tested on air at or near standard conditions. A blower for hot gas is not usually tested at its operating temperature. Its performance at temperature is calculated from the test results by applying the density correction, and the speed limit and mechanical design are checked separately. Ask how the hot-gas performance has been derived. See gas temperature, altitude and density correction.

Reading a Test Report

A useful report states:

1. The standard and edition used.
2. The installation category.
3. Blower model, wheel diameter, and blade type.
4. Speed, gas density, and test conditions.
5. Pressure basis, static or total.
6. Flow, pressure, power, and efficiency across the range, not only the duty point.
7. Measurement uncertainty.
8. Whether the tested blower matches the one supplied.

Questions to Ask Any Blower Manufacturer

• Is the published curve from a test to ISO 5801 or AMCA 210, or is it calculated?
• What installation category does it represent?
• Was the actual size tested, or scaled from another?
• What tolerance applies to flow, pressure, and power?
• Can you provide a witnessed test or a report for this blower?
• What density and speed is the curve corrected to?

Performance Guarantees and Site Acceptance

Where performance is critical, agree in the contract how it will be proved: a factory test, a witnessed test, or a site test to ISO 5802. State the tolerance, the pressure basis, the gas density, and who bears the cost. Without this, a dispute over a small shortfall is hard to settle, since real installations rarely match an idealised airway.

What a Performance Guarantee Should Say

A useful guarantee names the duty point: airflow, pressure, and the pressure basis, at a stated gas density and speed. It states the tolerance on flow, pressure, and power, the standard and installation category the test follows, and where and when the test will be done. It says what happens if the blower misses the guarantee: adjustment, replacement of the wheel, or a price reduction. And it says who supplies and pays for the test instrumentation. Guarantees that omit any of these tend to become arguments. For hot-gas duties, the guarantee should state how performance at temperature will be derived from the test on air.

Where Our Range Fits

NextAir Systems manufactures centrifugal blowers up to 800 HP (about 597 kW) and up to 500 mm WC (about 4.9 kPa) static pressure. Tell us the performance basis and acceptance method your project needs, and we will confirm what performance data and testing we can provide.

Ask for Test-Based Performance Data

Tell us your duty and installation arrangement, and we’ll explain what performance data we can provide. Contact us for a free quote.

Frequently Asked Questions