The difference between E, EW and EI: classifications explained

The classification EW combines integrity (E) with a limitation of heat radiation (W). Under the W classification, the heat radiation measured at 1 metre from the unexposed side of the fire curtain may not exceed 15 kW/m².

This means that, alongside maintaining integrity, the amount of radiant heat on the unexposed side is also limited. That can matter for the protection of people and materials, and in situations where the heat radiation on the other side of the fire separation has to be restricted.

A classification such as EW 60, EW 90 or EW 120 indicates for how many minutes both the integrity criterion (E) and the reduced heat radiation criterion (W) are met.

Please note: the W classification concerns the limitation of heat radiation and is not the same as the thermal insulation classification I of, for example, an EI-classified fire curtain.

The classification EI combines integrity (E) with thermal insulation (I). Alongside maintaining integrity, requirements are set for the temperature rise on the unexposed side of the fire separation.

For criterion I (thermal insulation), the average temperature rise on the unexposed side may not exceed 140 °C, among other requirements. Criteria also apply to the maximum permitted local temperature rise. Depending on the type of element and the classification concerned, a distinction may be made between EI₁ and EI₂.

A classification such as EI₁ 60 or EI₂ 120 indicates for how many minutes both the integrity criterion (E) and the relevant thermal insulation criterion (I) were met during the standardised fire test.

EI is applied where, in addition to integrity, the temperature rise on the unexposed side has to be limited. Which fire resistance period and classification are necessary in a specific situation follows from the requirements set for the building and for the separation concerned.

The right choice of fire curtain does not start with the product, but with the fire safety requirement that applies to the separation concerned. Depending on the design and function of the fire separation, performance based on E, EW or EI may be required, combined with a particular duration, for example 30, 60, 90 or 120 minutes.

From requirement to the right classification

When selecting a fire curtain it is important to distinguish between the different performance criteria:

• E – integrity: assesses the integrity of the fire separation.
• EW – integrity and reduced heat radiation: in addition to the E criterion, the heat radiation on the unexposed side is limited.
• EI – integrity and thermal insulation: in addition to the E criterion, requirements apply to the temperature rise on the unexposed side. Depending on the classification, a distinction may be made between EI₁ and EI₂.

A longer duration does not automatically replace a classification with different performance criteria. E 120, for example, is not equivalent to EW 60 or EI 60. E, W and I represent different fire resistance criteria.

Not only the classification counts, but also the field of application

A designation such as EW 120 or EI₂ 120 is not in itself sufficient to establish whether a fire curtain is suitable for every situation. The stated performance must be substantiated by the test and classification documentation that applies to the product.

The field of application of the demonstrated performance also has to be considered. Dimensions, mounting method, supporting construction, connection details and configuration, among others, can determine whether the tested and classified performance applies to the project situation concerned.

The project specification is decisive

In the Netherlands, the fire safety requirements for a building are set by the Dutch Building Decree (Besluit bouwwerken leefomgeving, Bbl) and the assessment methods it designates. In addition, the fire safety concept, the specification or the fire safety consultant may lay down supplementary or more specific performance for a particular separation.

We therefore advise against looking solely at the number of minutes of fire resistance when selecting a fire curtain. Always check:

• which performance is required;
• for how long that performance must be delivered;
• whether the chosen curtain construction demonstrably delivers that performance for the application concerned.

Protektis thinks along from the specification onwards

Protektis therefore does not assess an enquiry on the basis of the desired dimensions alone. We look at the required fire resistance classification, the project situation and the available test, classification and product documentation.

That allows us to advise precisely which type of fire curtain matches the project specification technically, and which documentation is available to substantiate the stated performance.

Do you have a specification, a fire safety report or a prescribed classification such as E, EW, EI₁ or EI₂? Send it to us together with the dimensions and the project situation. We will assess which curtain solution fits.