What is E, EW, and EI for Fire Curtains?

Ensuring fire safety in a building is crucial. To assess the effectiveness of barriers like curtains, doors, and glass in stopping fire spread, a fire classification system has been established. This system provides a universal standard, making it easier to determine if a product meets your building’s safety requirements, potentially saving lives.

The classifications are as follows: E (integrity), EW (integrity and radiation), and EI (integrity and insulation). Each is measured in minutes, indicating how long the product performs under specific test conditions. In this article, we explore how these classifications are determined and their practical implications.

How to Define the E/W/I Standards for Fire Curtains and Test Their Compliance?

Before understanding what E/I/W is, we must know which standards define E/I/W and the methods used to test them, in order to classify the fire protection devices’ rating.

Understanding the EN 13501-2 Standard for Fire-Resistant Products: Classifications and Criteria

The EN 13501-2 standard serves as the European benchmark for classifying construction elements based on their fire resistance. It applies to various products such as doors, windows, glazed partitions, curtains, and other fire-resistant barriers, assessing their capabilities to contain flames, restrict heat flow, and prevent the release of toxic smoke.

Evaluation Criteria of the EN 13501-2 Standard

The EN 13501-2 standard relies on three key criteria:

• E / Flame Seal
  This criterion prevents the spread of flames and hot gases through the construction element. It is the minimum requirement for a product to be deemed fire-resistant.
• I / Thermal Insulation
  This aspect limits the temperature increase on the non-fire-exposed side, thereby preventing the transfer of heat that could ignite nearby materials.
• W / Thermal Radiation
  This criterion gauges the heat emitted from the burning element and its effects on adjacent combustible materials, thus protecting individuals and objects in the vicinity from excessive heat.

EN 1634-1 Standard: Defines Testing Methods to Achieve E/W/I Ratings

EN 1634-1 tests fire curtains to determine if they achieve E/W/I ratings, focusing on three main aspects: preparation before testing, the testing process, and the assessment criteria for rating.

Preparation Before Testing

Samples must undergo pre-treatment in accordance with the requirements of EN 1363-1. Details for the treatment of support structures should refer to Annex A of the standard. For instance, certain grouting or sealing materials may require a curing period of 7 or 28 days. Additionally, the fire curtain product must complete necessary mechanical adjustments to ensure it is in optimal working condition.

Testing Process

The fire resistance test is conducted according to the standard temperature rise curve specified in EN 1363-1 (T=345 log₁₀(8t + 1) + 20), simulating the entire development process of a fire from its initial stages to flashover. The sample is installed on a support structure that complies with regulated types, and the installation method should mimic actual usage as closely as possible to ensure the test results are representative and applicable to engineering.

Assessment Criteria for Rating

• Integrity (E) Rating Assessment: Integrity primarily measures the fire curtain’s ability to prevent flames and hot gases from penetrating under high-temperature conditions. If the following occurs—ignition of the cotton pad, flames on the non-exposed side lasting more than 10 seconds, a 6mm probe can penetrate cracks extending ≥ 150mm, or a 25mm probe can directly pass through cracks—integrity is deemed to have failed, and the corresponding E rating cannot be achieved. Conversely, if these situations are avoided, the integrity requirements are met.
• Insulation (I) Rating Assessment: Insulation assesses the fire curtain’s capability to inhibit heat transfer. This is judged by controlling the temperature rise on the non-exposed side. The average temperature rise must not exceed 140°C, with the highest temperature point of the frame under normal conditions (I2 classification) ≤ 360°C, and other maximum points ≤ 180°C. Under supplementary conditions (I1 classification), all maximum points must be ≤ 180°C; meeting these criteria allows for the corresponding I rating; otherwise, it does not conform.
• Radiation (W) Rating Assessment: Thermal radiation measures the fire curtain’s ability to block high-temperature radiation. Measurement includes total heat flux from convective heat transfer, recording the time points at which radiation values first exceed “5, 10, 15, 20, 25 kW/m²”. When the heat flux 1m away from the surface of the door remains below 15 kW/m² within the specified time, it conforms to the thermal radiation protection standards, achieving the respective W rating requirements.

What is E (Integrity)

The E classification, or integrity rating, is the most common fire classification. It measures how well a barrier, like a fire curtain, door, or shutter, can prevent flames from passing through when exposed to fire on one side.

During testing, one side of the product is heated to over 1000°C using a furnace, following a standardized heating method (such as BS EN 1363-1). The test evaluates three criteria to determine if flames penetrate the barrier:

1. Cracks or openings in excess of a given dimension appear in the product.
2. A cotton pad on the unexposed side ignites.
3. Sustained flaming occurs on the unexposed side.

The test concludes when any of these occur, or the manufacturer may end it earlier if the product meets the desired performance level. The result is given as EXXX, where XXX indicates the duration in minutes.

It’s important to note that integrity tests do not measure heat transfer through the product; this is assessed by other classifications.

What is EW (Integrity and Radiation)

In the EW rating, besides assessing integrity, the product’s ability to limit heat radiation from the unexposed side is also evaluated. This is crucial for ensuring safe conditions, allowing people time to evacuate a building.

During testing, two heat flux meters are positioned 1 meter from the unexposed side to measure the thermal energy radiated over a specific area and time. One meter is centered on the product to obtain an average reading, while the other measures the maximum likely heat flux.

The test ends when either the integrity fails or the heat flux exceeds 15 kW/m², whichever occurs first.

What is EI (Integrity and Insulation)

The EI rating is the highest classification level for fire curtains. It evaluates both fire integrity and the product’s ability to resist heat conduction to the unexposed side. This is crucial for protecting people and preventing nearby materials from igniting.

The insulation aspect measures the time it takes for the unexposed surface to reach 140°C above its initial temperature. The test concludes when this temperature is reached or when integrity fails, whichever comes first.

Difference between EI1 and EI2

1. Definition

• EI1: Refers to fire resistance that combines integrity (E) and insulation (I) under standard fire conditions, usually with stricter requirements for the maximum temperature rise on the non-exposed side. This classification is typically used in critical applications where lower temperature rises are essential to prevent fire spread and protect adjacent areas.
• EI2: Represents a similar combination of integrity (E) and insulation (I) but allows for higher temperature rises compared to EI1. It is generally suited for less critical applications where slight increases in temperature on the non-exposed side are permissible.

2. Performance Criteria

• Temperature Rise:
  • EI1: The maximum allowable temperature rise on the non-exposed side is more stringent. For example, the average temperature rise must not exceed 140°C.
  • EI2: Allows for a higher maximum temperature rise, which can be over 180°C for specific points.
• Integrity:
  • Both classifications evaluate the fire compartment’s ability to maintain integrity; however, the conditions under which this is assessed may vary slightly due to the temperature rise allowances.

3. Applications

• EI1: Used in high-risk areas where fire spread needs to be strictly controlled, such as in high-rise buildings, hospitals, or data centers where critical equipment is housed.
• EI2: More suitable for standard buildings where fire protection is important but not as critical, such as offices and residential buildings.

Breaking Down EI Ratings: What Different EI Levels Are Used For

An EI classification is by no means random. It indicates the duration a product can sustain both its integrity and insulation when exposed to standard fire conditions. Take EI60 as an instance: it signifies that a component is capable of resisting fire and heat for 60 minutes, with this performance having been confirmed through strict laboratory testing.

EI30: The most basic standard

An EI30 rating offers 30 minutes of fire resistance. As the minimum standard specified by most fire safety regulations, it applies to internal components in residential buildings and small-scale commercial premises. The purpose of this rating is straightforward: to contain fires for a sufficient duration to enable safe evacuation and early firefighting intervention.

EI60: The Commercial Standard

An EI60 rating delivers twice the level of fire protection compared to lower grades like EI30. This classification is indispensable for multi-storey structures, public corridors, and all buildings with a large number of occupants. In numerous instances, it is mandated by Building Regulations—this is especially true for protected escape routes in buildings that exceed 11 meters in height.

EI90: The High Risk Standard

EI90 is not intended for light-duty applications. Instead, it is designed for high-risk environments—such as locations where volatile materials are handled, areas with concentrated critical infrastructure, or sites where asset loss would result in catastrophic consequences.

EI120: The Maximum Civilian Protection Standard

The EI120 rating represents the highest level of fire resistance utilized in both public and residential buildings. It provides certified protection for up to 120 minutes in extreme fire conditions. This rating is not merely a matter of choice; it is essential for systems that are critical to life safety.

Suntex provides the fabric needed for fire curtains

As a leading manufacturer of fire-resistant and high-temperature textiles, Suntex offers a range of fireproof materials for making fire curtains. These materials include

Note: Suntex can provide various fireproof fabrics for different grades of smoke curtains or fire curtains. However, we do not provide technical assistance or design methods for manufacturing fire curtains.

To learn more about smoke & fire curtain fabrics, click ⬇.

Test Report for Suntex Fabric @1100°C in 180 mins

Statement

The results only relate to the behaviour of the specimen of the element of construction under the particular conditions of the test. They are not intended to be the sole criteria for assessing the potential fire performance of the element in use nor do they reflect the actual behaviour in fires.
The test results relate only to the specimen tested. The fire resistance performance of specimen of this design may change if different dimensions, different gaps, incorporating different components, or mounted within different wall constructions.

Test result curve

The following data were collected during the test:
a) The average temperature/time curve in the furnace, see attached Figure 1.
b) The furnace actual pressure/time curve, see attached Figure 2.
c) Suntex fireproof fabric test @180min 1100C for fire curtains. Before/After test, see Figure 3.

Gallery of Suntex Fabric Fire Test

Tag: Fire & Smoke Curtain, Fire Control