ATEX Compatible Radial Fan for Chemical Plants

Start choosing an ATEX-compliant radial fan for chemical plants with three pieces of information before the engine model: the classification of the area where the fan will be installed, the properties of the gas that will pass through the fan, and the flow-pressure operating point of the process. The explosive atmosphere in the installation area and the gas carried by the fan are not the same assessment; the presence or absence of both and the extent of use of the product should be technically examined.

Hazardous area classification in Turkey is part of workplace risk assessment; Product suitability is checked by the purpose of use of the fan and the scope of marking ([Turkish Product Rules](https://urunkurallari.ticaret.gov.tr/tr/sektorel-rehber/patlayici-maddeler), [1999/92/EC](https://eur-lex.europa.eu/eli/dir/1999/92/oj/eng)). Flow rate and total pressure, temperature/density of gas and channel should be specified with filter losses. Chemical composition, the possibility of condensation and design temperature also affect the choice of body, impeller and seal. EN 14986:2024 covers the design, manufacturing, testing and marking of fans operating in explosive atmospheres as a whole unit; The transport medium can be located inside, outside or on both sides of the fan ([NEN](https://www.nen.nl/en/nen-en-14986-2024-en-323624), [BSI](https://landingpage.bsigroup.com/LandingPage/Undated?UPI=000000000030115505)).

How to separate Zone knowledge and product suitability?

Hazardous area classification in the chemical plant is determined by workplace risk assessment and frequency/duration of occurrence of the explosive environment. This classification is the initial input for equipment selection; The scope of use given by the fan manufacturer for a particular product should be checked separately. Product conformity with workplace classification is not the same document or the same responsibility. Directive 1999/92/ECregulates the separation of places where explosive atmospheres may occur into zones by the employer. Relevant regulation on the product side in Turkey In the Ministry of Commerce Product Rules Database Associated with regulation 2014/34/EU.

It is not enough to just write “Zone 1” or “Zone 2” in the technical request. Whether gas/steam or dust is involved; what intended use and scope of marking the product concerned has; It should be checked whether the expected operating conditions remain within the manufacturer’s instructions. The final zone classification should be determined by the facility’s responsible occupational safety and process teams, not the fan supplier.

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Why are the environment in which the fan is installed and the process gas transported evaluated separately?

The fan may be carrying a different gas than the outside environment. Therefore installation area and the fluid passing through the fan two separate questions should be asked: Can an explosive atmosphere form around the fan? Can the transported process gas create an explosive atmosphere inside the fan? Both responses should be included in the technical documentation.

EN 14986:2024 scope description states that explosive atmosphere may be present inside, outside or on both sides of the fan; It states that the standard relates to the design, manufacturing, testing and marking of the fan unit (NEN-EN 14986:2024). Thus, it may be incomplete to assess only the area where the engine is located or only the process gas. The process conditions on the fan position, channel route, suction and discharge side should be considered together.

Misknown: If the outside area of the fan is classified, there is no need to examine the gas carried by the fan separately.
Correction: The gas transported and the installation area are separate variables. It must be verified that both conditions correspond to the scope of use of the product.

How do flow rate and pressure determine the radial fan operating point?

Radial fan selection is not just about writing the target flow rate and choosing a model from the catalog. The fan must provide the desired operating point in the total resistance of the duct and process components to which it is connected. Filter, damper, channel length and elbows contribute to the total pressure requirement. If these values change, the operating point may also change.

In chemical processes, it should be clearly written under what conditions flow rate and pressure values are given: gas temperature, density, pressure state and design situations outside normal operation. The proposed point in the fan performance curve must be compared with the expected operating condition of the system. The suitability of the radial fan is determined not by “because it is radial” but by the fact that the process meets the flow rate and pressure requirement.

Engineering grade: When the process gas temperature changes, the density and thus the operating conditions of the fan may also change. In the proposal comparison, therefore, match not only the values “m³ /h” and “Pa”, but also the gas conditions under which these values are defined.

How to choose chemical resistance, material and shaft sealing?

“Chemical-resistant fan” is not a material specification on its own. Acid, base, solvent or mixtures thereof; It may cause different effects in the gas phase, condensed liquid or with particles. When selecting the body and impeller material, the chemical composition, concentration, temperature, humidity and the possibility of condensation should be considered together. It should not be assumed that a particular alloy or plastic material is suitable for every process.

There is no single general solution for shaft sealing either. The pressure condition, the characteristics of the gas, the temperature, the maintenance requirement and the emission expectation of the installation must be described in the technical request. The wording of the seal should be supported by the acceptance criterion and the product design; it should not be used in isolation as a guarantee of absolute results.

In our opinion, it is the most critical mistake, is to make the choice of material solely on the basis of the commercial name of the gas. A material decision made without knowing the actual composition of the chemical and condensation conditions may be insufficient in terms of fan life and maintenance needs.

How to verify ATEX compliance for fan unit and motor?

Using an ATEX motor does not mean that the entire fan unit is automatically suitable. The motor, fan wheel, body, shaft, bearing, sealing, sensors and connection arrangement must be evaluated within the selected product configuration. The model and condition of use for which product conformity is granted must be verified on manufacturer’s documentation and marking.

The current version of EN 14986’ is EN 14986:2024’; BSI lists the current release as May 3, 2024 (BSI standard sheet). This standard provides information about the mechanical design and testing scope for the fan unit; It does not replace the facility’s zone classification or process risk assessment.

Share your process data and fan needs with the Efsan team.

What information and documentation should be required for a technical proposal?

Ensure that the same data set is communicated to all suppliers before comparing offers. Missing process inputs make it difficult to technically compare proposals prepared with different assumptions.

1. Specify the field condition: Zone classification, gas/dust type, fan location and location in the process line.
2. Identify the fluid being transported: Gas composition, temperature, density, humidity and possible condensation.
3. Type the working point: Flow rate, total pressure and for which operating condition these values are required.
4. Add material and sealing requirement: Chemical compliance, design temperature, emission or maintenance expectation.
5. Verify the offer file: Product marking and instructions for use, documentation within the fan and motor scope, performance curve, material information and confirmation of the selected operating point.

Mini example: Line from reactor outlet to scrubber

The following example is hypothetical: solvent vapour from a reactor outlet will be transported through the duct to the scrubber. The first step is not to choose a fan brand; It is to separately collect the gas composition and temperature, the required flow rate, channel-scrubber pressure losses and the classification of the area where the fan will be located. Although the area where the fan is located is classified, the gas passing through the fan is examined separately. Then the material and sealing requirement are determined; The desired operating point in the proposed fan curve is checked. It is confirmed that the product documentation also belongs exactly to the proposed fan configuration.

This is not a sample product or model recommendation. Without gas composition, operating condition and site classification, it would not be correct to recommend a model or ATEX marking.

To evaluate the flow rate, pressure and gas data of your chemistry process with the technical team Contact Efsan.

Frequently asked questions

Who determines the zone information for fan selection in the chemical plant?

Zone classification is determined by the relevant responsible teams within the scope of the facility’s workplace risk assessment. The fan supplier matches this input to the scope of use of the product; it is not a substitute for plant classification. 1999/92/EC

Is a standard fan with an ATEX motor considered ATEX suitable?

It is not enough to just look at the marking of the engine. The proposed fan configuration and conditions of use must match the product documentation.

How should fan flow rate and pressure be specified?

Flow and total pressure should be given together with the temperature/density conditions of the gas and the pressure losses of the connected equipment. The operating point in the performance curve should be compared with these conditions.

How to choose fan material for chemical gas?

The composition, concentration, temperature, humidity and possibility of condensation of the gas must be taken into account. Instead of a general definition such as “chemical resistant”, material compatibility should be confirmed through process data.

What documents should I request when requesting a quote?

Product marking and instructions for use, relevant certificates of conformity, engine documentation, fan performance curve, material information and confirmation of conformity to operating conditions of the proposed configuration should be required.