ISO 5801 Fans - Performance Testing Using Standardized Air Paths

The ISO 5801 Fans - Performance testing using standardized airways standard, developed by the International Organization for Standardization (ISO), describes procedures for determining the performance of all types of fans except those designed solely for air circulation. Examples include ceiling fans and desk fans. Testing jet fans is described in the ISO 13350 Fans - Performance testing of jet fans standard. This standard includes rules for estimating measurement uncertainties and converting test results within specified limits for changes in speed, gas used, and dimensions in the case of model testing.

For the purposes of this standard, the following definitions apply in addition to the terms and definitions given in “ISO 13349 Fans - Vocabulary and definitions of categories”:

• The pipe cross-sectional area is the area of ​​the pipe at cross-section x.
• The fan inlet area is the surface plane bounded by the upstream end of the air moving device. The fan inlet area is conventionally taken as the gross area at the inlet plane inside the enclosure.
• The fan outlet area is the surface plane bounded by the downstream end of the air moving device. The fan outlet area is conventionally taken as the gross area at the outlet plane inside the enclosure.
• Temperature is the air or liquid temperature measured by the temperature sensor.
• Absolute temperature is the thermodynamic temperature. In this standard, the absolute temperature Q is expressed in Kelvin and the temperature T in degrees Celsius.
• The equation of state for an ideal dry gas is given in the standard.
• The equation of state for an ideal gas and an isentropic process is given in the standard.
• The equation for specific heat capacity at constant pressure for an ideal gas is given in the standard.
• The equation for specific heat capacity at constant volume for an ideal gas is given in the standard.
• The compressibility factor equation for an ideal gas and for a real gas is given in the standard.
• The stagnation temperature at a point is the absolute temperature at an isentropic stagnation point for ideal gas flow without the addition of energy or heat. The stagnation temperature is constant throughout an air path and is equal to the absolute ambient temperature in the test enclosure for an inlet duct. For Mach numbers less than 40, obtained for standard air with duct velocities less than 0,122 m/s, the stagnation temperature is almost the same as the total temperature.

Briefly, the main features of this standard are:

• Installation categories and test configurations: Because the connections of a duct to a fan inlet or outlet affect the performance of the fan, a number of installation categories and test configurations must be recognized.
• Common segments: It is essential that all standard test air paths for use with fans have common sections adjacent to the fan inlet or outlet that are sufficient to allow consistent determination of the fan pressure. The geometric variations of these common segments are strictly limited.
• Flow rate measurement: Determining the flow rate is separated from determining the fan pressure. A number of standard methods can be used.
• Test results: The measurement and calculation methods for flow rate, fan pressure and fan efficiencies are determined by taking into account all compressibility effects of air. For fan pressures lower than 2000 Pa, the density change between the fan inlet and the fan outlet is allowed to be neglected. Other compressibility effects are allowed to be neglected for reference speeds not higher than 65 m/s.

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