Protective Clothing with Electrostatic Properties
EN 1149:2008 is a European standard for safety garments protecting wearers against electrostatic discharge in working environments with explosive risks. Such environments are sometimes referred to as ATEX Environments, as per the two European directives for controlling explosive atmospheres. Materials tested using the tests methods outlined in EN 1149:2008 indicate safe electrical discharge properties when posed with the conditions of explosive environments.
Bool produces anti-static clothing made with materials engineered to suppress static charge, thereby preventing sparks, which might cause a fire or explosions. Such clothing can be worn in oxygen-enriched environments; however, it does not protect against electric shocks.
Garments intended to be used in explosive environments must not conduct electrostatic charges from the air. EN 1149:2008 is divided into five parts:
|Test Method||Description||Minimum Compliance Values|
|EN 1149-1||Electrostatic properties (surface resistivity)||Surface resistance is ≤ 2.5x109|
|EN 1149-2||Electrostatic properties |
(electrical resistance through a material, vertical resistance)
|Electrical resistance > 105W|
|EN 1149-3||Electrostatic properties (inductive charge)||Surface resistance is ≤ 2.5x109|
|EN 1149-4||Garment test methods||yet to be published|
|EN 1149-5||Electrostatic properties. Performance requirements and material design||t50 ≤ 4s or S > 0.2; |
or Surface resistance is ≤ 2.5x109
This test method measures surface resistivity by determining how the fabric surface resists the dissipation of a charge. This test ensures that the charge will not develop to the point where it can generate a spark.
The determined surface resistance of the fabric is to be 2.5x109 Ohms (Ω) or less. This method is not appropriate for core conductive fibres. A material is either tested to EN 1149-1 (Surface resistance) or EN 1149-3 (Charge decay) as these tests measure two aspects of the same property.
The second part of this standard outlines procedures to measure the vertical resistance of the material sample. Vertical resistance refers to the tendency of the fabric to allow charge to pass through the thickness of the material. It is primarily used to test heavier weight fabrics that are woven. It is not used to specify protection against mains voltage. Electrical resistance must be greater than 105W to pass this test.
The EN 1149-3 test reveals the ability of the garment's fabric to dissipate electrostatic charge from across its' surface. This process ensures that the material discharges any electrostatic charges to the air and will not conduct it to the users clothing, therefore eliminating the risk of conductivity for the wearer and the risk of a potential explosion.
Garment Test Method
Part 4 of the standard is yet to be formally published. It was originally outlined as a testing method for the garment in its entirety.
EN 1149-5 draws upon the results of tests conducted in parts 1 to 3 to develop performance requirements for an anti-static garment. They may be tested according to the appropriate test methods outlined in parts 1 to 3, but can only be certified to part 5, after meeting stipulated performance requirements.
For FR garments which are worn by electrical workers and other industries working with fire, this clause is specifically focused on the overall garment construction, ensuring that the amount of fabrics, reflective tape and other components are assembled for maximum safety performance.
To be compliant to part 5 of EN 1149 the garment must also display the following information on the 'User Instructions:'
- a warning that the garment must be earthed to allow grounding of a charge should not be opened or removed in an explosive atmosphere
- clothing is suitable for wearing in ATEX Zones 1, 2, 20, 21 & 22 but that use in Zone 0 or in oxygen enriched atmospheres should be authorized by a qualified safety engineer.