EN 1149: Electrostatic properties of protective cloth
In the 1149 series, there is also an EN 1149-2 (measurement of the electrical resistance through a material; the vertical resistance) which is used as a test method in EN ISO 11611 (welders clothing) and which is also mentioned in Annex H of EN 469:2005. A full garment test is under development and will be issued as EN 1149-4.
Protective clothing – electrostatic properties.
BS EN 1149-5 is part of a series of standards for test methods and requirements for electrostatic properties of protective clothing.
BS EN 1149-5 specifies material and design requirements for electrostatic dissipative protective clothing. It covers clothing used as part of a total earthed system, to avoid incendiary discharges.
The requirements may not be sufficient in oxygen enriched flammable atmospheres. This standard does not apply to protection against mains voltages.
Anti-static fabrics are used in environments where there is a risk of explosion (ATEX environments).
Annex II, art. 2.3. of the ATEX directive 99/92/CE concerning the protection of workers likely to be exposed to the risk of explosive atmospheres says: “Workers must be provided with appropriate working clothing consisting of materials which do not give rise to electrical discharges that can ignite explosive atmospheres”.
Under the scope of the PPE manufacturers Directive 89/686/Ce a series of protective clothing standards have been developed relating to electrostatic properties:
EN 1149-5:2008 – Performance requirements
Anti-static PPE are certified to EN 1149-5 as this standard covers the performance requirements and refers tot the choice of 2 different test methods (EN 1149-1 or EN 1149-3)
EN 1149-1:2006 – Measurements of surface resistivity
This test method is most appropriate for materials for which the electrostatic dissipative behavior is based on surface conductivity (for instance containing surface conductive yarns or a homogenous conductive outside PVC coating layer). This method is not appropriate for core conductive fibres.
EN 1149-3:2004 – Test methods for measurement of charge decay
This test method is referenced for materials for which the electrostatic dissipative behavior is based on core conducting fibres but can also be used for surface conducting materials.
Conductive threads are usually manufactured for anti-static, electromagnetic shielding, intelligent textiles, wearable technology, data transfer and heating purposes. Most threads are metalized with an alloy of various metals, which can include silver, copper, tin and nickel. The core is normally cotton or polyester.
Conductive threads are uninsulated and sewing them tightly to metal usually makes for a good connection, though this connection tends to loosen over time where movement occurs. One way of avoiding this is to include a squishy material, such as stretch conductive fabric underneath the stitches, or a non-conductive material, so long as it does not obstruct the electrical connection.