TTM-01: Determination of duty point of fanebm-papst fans for outdoor applications

Even though IP rating is an important factor in selecting the right product for a certain application, it is not the sole deciding factor. The ebm-papst protection class also needs to be considered.

ebm-papst protection classes

We often get asked for IP ratings on fans as these have been specified. However, the perception in the market that a certain IP rating is required for certain environmental conditions is not always correct due to the mechanical layout of our fans, i.e. our use of external rotor motors.

IP rating is defined in standard AS 60529-2004 – Degrees of protection by enclosures (IP Code) and provides details on protection classes by enclosures from solid foreign objects and water.

For example: some of our IP54 fans are suitable for spray water only and some for even corrosive environments like salt spray, which for example could be required in applications in coastal regions of Australia and New Zealand. To us these are separate protection classes and hence separate fans. Some IP54 fans are protected to ensure functionality only and some are protected for functionality and visual appearance. The different protection classes depend on:

  • motor type and layout, for example AC or EC motor
  • if certain fan components like stator or PCB are impregnated/coated and type of impregnation/coating
  • if certain fan components like grille or impeller are painted and the method of painting

Therefore ebm-papst have defined their own protection classes. This allows the customer to select the water and humidity protection for a fan based on the application, and without having to consider the IP rating of the fan, thereby being able to cover the specifications required.

Each protection class refers to certain ambient conditions, for example spray water or salt spray, and typical applications and environments for which these ambient conditions apply (cf. Figure 1). Using this criterion, you can select which ambient conditions are most relevant for your application. For example: the application may involve humidity with condensation in evaporator applications. Here we would recommend F2 rather than specifying an IP rating because the latter would not necessarily give a protection class that is suitable for the application.

The variety of possible protection classes is highlighted in table 1. It shows that different products with the very same IP rating can be suitable for very different exposures to humidity and water.

IP class
Possible protection classesPossible ambient conditions based on protection class
IP54 F3-1, F4-1, F4-2Spray water, salt spray, protection of functionality only or protection of functionality and appearance
IP44IP44 F1-2, F2-2, F3-1Humidity without condensation, humidity with condensation, spray water, protection of functionality only or protection of functionality and appearance
IP20IP20 F0, F3-1 No humidity, spray water


Let us look at the example of an 800mm axial fan with an EC motor that has a protection class F4-1. This fan has IP54 classification.

Fans with protection class F4 are designed for applications with high level of humidity in a corrosive environment, for example salt spray. The protection is solely intended for function and safety and not for visual appearance. This is reflected in the second number of the protection class, in this case -1. If protection for visual appearance is also required, a fan with protection class Fx-2 needs to be selected.

To verify the conformity of a product to protection class F4-1, we carry out salt spray loading tests acc. to DIN EN 60068-2-11, with test duration of 14 days and test specimens tested in their least favourable installation condition.

After test completion, the test specimens are evaluated for safety (leakage current acc. to chapter 16 of DIN EN60335-1 and protective wire protection acc. to chapter 27 to DIN EN 60) and functionality (power and current intake acc. to chapter 10 of DIN EN 60335-1).

For all other ebm-papst protection classes, similar tests and evaluations are carried out. For further details on the different ebm-papst protection classes we can supply you with our brochure: “ Climate & humidity protection for fans”.

Tests to confirm suitability

We carry out longevity tests to verify the suitability of our products for certain operating conditions. These tests include outdoor tests, for example the long-term HyBladeTM test in Singapore (high humidity), and long-term tests in an endurance test chamber where different temperature and humidity profiles can be simulated.

Temperature and humidity profile for long term test in Singapore

Figure 2: Outdoor fan test Singapore

Different HyBladeTM axial fans were set up outdoors in Singapore where they were exposed to weather. For weather details in Singapore (cf. Figures 3 and 4).

  • Products: various HyBladeTM fans (axial fans), size 630, 710 and 800 with AC- and EC-motors.
  • ebm-papst protection class F4-1
  • IP-rating 54
  • Test conditions:
    • AC fans running in start-stop-operation
    • EC fans running at various speeds
    • Fans exposed to weather in Singapore
  • Result: Fans were found to be suitable for outdoor operation in humid climate
Temperature and humidity profile Singapore, source ebm-papst

Long-term test in endurance test chamber

EC axial fans rainwater test
Figure 5: 800mm EC axial fans with AxiTop in endurance test chamber during splash water test

Our endurance test chamber in Mulfingen, Germany, consists of 10 different long-term test rooms which allow ebm-papst engineers to run long-term tests on approximately 2,000 products at the same time. Different chambers cater to different environmental conditions, like high or low temperature, varying temperature profiles, high or low humidity, splash water, dust and many more.

One of the products tested in our endurance test chamber is the 800mm EC axial fan with AxiTop.

  • Fan type: 800mm EC axial fan with AxiTop
  • Protection class F4-1
  • IP-rating 54
  • Test conditions:
    • Temperature profile from -10°C to +60°C
    • Intermittent rain
    • Duration: min. 900 cycles which equals min. 180 days
  • Result: Fans were found to be suitable for operation in humid environment with splash water (rain).


Even though IP rating is an important factor in selecting the right product for a certain application, it is not the sole deciding factor. The ebm-papst protection class also needs to be considered. Extensive testing confirmed the validity of this protection class.

If you are in doubt which protection class is required for your application or if you would like to receive further details on this topic, please contact your ebm-papst representative.