PROTECTIVE CLOTHING – ELECTROSTATIC PROPERTIES – PART 5: PERFORMANCE REQUIREMENTS
Antistatic clothing suppresses static charge, thereby preventing sparks, which might cause a fire or explosions. EN 1149-5 is part of a larger system.
EN 1149 consists of the following parts:
EN1149-1: test methods for the measurement of surface resistance
EN1149-2: test methods for the measurement of the electrical resistance through a material (vertical resistance)
EN1149-3: test methods for the measurement of charge decay
EN1149-4: garment test method (standard currently under development)
EN1149-5: performance requirements.
The contents of this standard
This standard specifies requirements for clothing that conducts electricity. This clothing (combined with e.g. shoes that conduct electricity) forms part of a completely earthed system. The clothing prevents sparks and therefore explosions.
Clothing made to this standard is only accepted in combination with the standard for flame retardant clothing (531 or 11612). This clothing is worn in explosion-hazard environments – if there is a risk of explosion, there is also a risk of fire. This clothing may not be worn in oxygen-enriched environments. It does not provide protection against electric shocks (mains voltage). EN 1149-5 compliant clothing is frequently used by companies that have to adhere to the ATEX guidelines.
Different tests
The fabric from which the clothing is made must be EN 1149-1, EN 1149-2 or EN 1149-3 compliant – or entire garments must be tested in accordance with EN 1149-4 (under development). XM Textiles manufactures ESD fabrics only with compliance to EN 1149 or EN 61340 standards.
EN 1149-1: Protective clothing – Electrostatic properties, part 1
The fabric releases its electrostatic charge via conduction. In the related test, the surface resistance is determined;
it has to be ≤ 2,5 * 109 Ω.
Electricity can be conducted via homogeneous or heterogeneous material. If the material is heterogeneous, static electricity has to be released via a grid of conductive fibres (metal/carbon) measuring max. 10 mm x 10 mm.
EN 1149-3: Protective clothing – Electrostatic properties, part 3
The fabric releases its electrostatic charge to the air (and not via conduction). The standard contains a test method in which the amount of time it takes for a static electrical charge to dissipate is measured (Electrostatic Discharge of clothing):
t50 < 4 s or S > 0.2
Where,
t50 = decay half time
S= shielding factor
The requirements set in this standard
– Materials that can carry an electric charge (metal buttons, etc.) must be covered on the outside
– Non-conductive elements (reflective strips, emblems, etc.) are permitted, provided they are permanently attached. For example, a removable badge is therefore not permitted
– Clothing that complies with EN 1149-5 is in itself insufficient; the wearer must also wear shoes that conduct electricity
– The outer material must always be in contact with the wearer’s skin. When designing, for example, winter clothing, the seam must therefore be in contact with the skin.