Flammability testing of curtains and drapes

Considering test methods used to assess the fire resistance of curtains, drapes and window blinds.

While the term ‘curtain’ can be used in a variety of situations, it is defined for this purpose as a large piece of fabric hung up as a screen – often across a window. The term ‘drape’, although less common in the UK, is sometimes used instead of ‘curtain’. A curtain may be tested to see if it is likely to catch fire when exposed to a flame. This flammability testing can be used to assess whether or not it is ‘safe’, meaning that it is unlikely to cause a hazard or bring harm to the user in normal use, or under foreseeable misuse. A window blind is similar to a curtain. Window blinds may have a roller arrangement with a fabric wound round a reel.

Background

Fires inside buildings can be started due to ignition by smoker’s materials, naked flames such as candles, or other intense heat sources. Being a vertically suspended piece of material, flames can spread readily up and across a curtain. The ignitability of fabrics varies – some fabrics catch fire readily, whereas others do not. Fabrics which have no inherent resistance to ignition may be chemically treated to make them resist ignition. Fabrics which have been treated in this way are often described as ‘FR-treated’ – ‘FR’ standing for ‘Flame Retardant’. FR treatment is intended to improve resistance to ignition, and also, should ignition take place, reduce the rate at which a flame will spread across a surface.

UK specification

Figure 1a: Type B testing, involving a 15-second flame application time, after which the flammability is assessed

BS 5867-2:2008 – ‘Fabrics for curtains, drapes and window blinds – Part 2: Flammability requirements – Specification’ sets out levels of performance based on testing to particular methods. This specification describes three levels – types ‘A’, ‘B’ and ‘C’. The requirements of Type A are the least severe, with the requirements of Type C being the most demanding. Each requirement type specifies a cleansing procedure to be used before the specimens are tested, in addition to the severity of the actual ignition test.

Figure 1b

The fire-retardant properties of the fabric (or fabrics) used to make the curtain drape or window blind may well be affected by the laundering processes to which they are subjected in actual use. The reason that the specification includes details of a cleansing procedure to be used prior to testing is to ensure that the fire-retardant treatment is retained during the life of the curtain – including through the laundering process.

Figure 1c

BS 5867-2:2008 specifies that the flame in the ignition tests is applied according to BS EN ISO 6941:2003 – ‘Textile fabrics – Burning behaviour – Measurement of flame spread of vertically oriented specimens’, and BS EN ISO 15025:2002 – ‘Protective clothing – Protection against heat and flame – Method of test for limited flame spread’. These test methods are referred to in BS 5867-2:2008. The principle of these tests is to apply a small gas flame to a vertically suspended piece of the curtain fabric for a specified number of seconds (between 5 and 30), and assess how the fabric behaves. The development of any holes in the fabric, or the way in which flames spread across the fabric, are assessed in order to determine if the test has been passed or failed. Whether or not there are flaming droplets that separate from the fabric specimen is also taken into consideration.

Figure 1d

If the curtain has a lining (that is, two pieces of fabric are used back-to-back), both the front and the back of the combination are tested.

BS 5867-2:2008 Types A and B testing

In both cases, specimens are tested before being subjected to a cleansing procedure. An anomaly in the standard is that it is not clear whether or not specimens must always also be tested after being subjected to a cleansing procedure (sections 5 and 6.2.1 refer). SATRA takes the view that it is a sound approach that the fabric is tested both before and after cleansing, as this ensures that any fire-retardant treatment will be durable in use. The cleansing method to be used for type A and type B testing should be the one that the supplier recommends for cleaning the curtain, with the instructions on the care label taken into account, or as detailed in the standard. If the supplier does not recommend a cleaning process or states that the fabric is unsuitable for cleaning, a simple water soak procedure (according to Annex D of BS EN 1021-1:2006) should be carried out.

In the case of Type A testing, the actual ignition testing is conducted according to BS EN ISO 6941:2003, in which a ten-second flame application is used. In the case of Type B testing (shown in figures 1a to 1d), the actual ignition testing is carried out according to BS EN ISO 15025:2002, and a 15-second flame application time is used. In all types of testing (A, B and C), the fabric specimen is suspended vertically, and the flame is applied to the surface of the specimen (not to the bottom edge).

BS 5867-2:2008 Type C testing

In Type C testing, the fabric must be tested before cleansing, and also after a cleansing procedure specified in BS 5867-2:2008. This consists of 50 cycles of a standard washing procedure specified in BS EN ISO 10528:1995 – ‘Textiles. Commercial laundering procedure for textile fabrics prior to flammability testing’.

Once again, the actual ignition testing is carried out according to BS EN ISO 15025:2002. A sequence of flame application times starting at five seconds and increasing in stages to 30 seconds is used.

BS 5867-2:2008 – ‘Labelling requirement’

To comply with this standard, curtains must carry a permanent label. The standard sets out information that must be present on the label, but it does state that this requirement does not apply for fabrics used by the UK Department of Health.

Regulatory framework in the UK

In the UK, there is no specific mandatory requirement that curtains supplied for domestic use are tested for flammability. Curtains are not included within the scope of the UK Furniture and Furnishings (Fire) (Safety) Regulations 1988.

The UK General Product Safety Regulations 2005 (which implement an EU Directive) require all products to be ‘safe’. Testing of products against standards is used by suppliers as evidence that the product is safe.
The non-domestic market for curtains is sometimes known as the ‘contract’ market. The fire safety of non-domestic buildings is controlled in the UK by the Regulatory Reform (Fire Safety) Order 2005, which imposes a duty on the operator of the building (such as a workplace, hotel, restaurant or hospital) to take responsibility for fire safety. Part of this responsibility includes the correct selection of curtains. Subject to a risk-assessment of the building and the activities that take place within it which might indicate otherwise, curtains that have passed the BS 5867-2:2008 Type B test are often regarded as suitable for non-domestic use.

Other standards

Readers may also be interested in the following European standards that are applicable to curtains and drapes:

BS EN 13772:2011 – ‘Textiles and textile products – Burning behaviour – Curtains and drapes – Measurement of flame spread of vertically oriented specimens with large ignition source’
BS EN 13773:2003 – ‘Textiles and textile products – Burning behaviour – Curtains and drapes – Classification scheme’
BS EN 1101:1996 – ‘Textiles and textile products – Burning behaviour – Curtains and drapes – Detailed procedure to determine the ignitability of vertically oriented specimens (small flame)’
BS EN 1102:1996 – ‘Textiles and textile products – Burning behaviour – Curtains and drapes – Detailed procedure to determine the flame spread of vertically oriented specimens’.