Static Dissipation

ELECTROSTATIC DISSIPATIVE GARMENTS EN 1149

Electrostatic Dissipative (“Antistatic”) Protective Clothing is designed to prevent incendiary discharges from the clothing and body. Discharges (sparks) from the human body and from clothing can ignite flammable gas, vapours, and dust clouds. The EN 1149 series of standards was developed to provide tests and requirements for fabrics and garments that would not ignite the most easily ignitable mixture of hydrogen gas and air.

Antistatic clothing on its own does not provide complete protection. The wearer must always be earthed.

The relevant parts of EN 1149 are:

 EN 1149-1:1995 Test method for surface conducting fabrics.

(Soon to be replaced by an updated version – no significant changes)

EN 1149-3:2004 Charge decay test method for all fabrics

EN 1149-4 Garment test method

EN 1149-5:2006 Performance requirements for fabrics and garments

 

1. EN 1149-5:2008 – Performance requirements

Anti-static PPE are certified to EN 1149-5 as this standard covers the performance requirements and refers to the choice of 2 different test methods (EN 1149-1 or EN 1149-3)

2. EN 1149-1:2006 – Measurements of surface resistivity

This test method is most appropriate for materials for which the electrostatic dissipative behaviour 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.

3. EN 1149-3:2004 – Measurements of surface resistivity

This test method is referenced for materials for which the electrostatic dissipative behaviour is based on core conducting fibres but can also be used for surface conducting materials

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. 

 

EN 1149-1 Electrostatic properties. Surface resistivity (test methods and requirements)

This test method is not applicable to fabrics with conductive fibre core. 

Homogeneous material: material in which the electrical properties of its components (wires layers) do not differ substantially from each other, or material containing an intimate mixture of conductive fibres

Inhomogeneous material: material which contains small amounts of threads distributed in a network, or material coated or laminated with polymeric or metallic materials and the properties of electricity were substantially different material components (e.g. more than one factor of 10) of each other

Test method: the sample is placed on an insulating base plate, then placed the group of electrodes on the sample, apply a continuous stream and measure the resistance of the sample

Requirements:  the surface resistivity must be less than 5 x 10¹⁰ Ω

The inhomogeneous material must have a conductive yarn net and the maximum distance between the conductive threads must be of 10 mm.

 

EN 1149-2 Electrostatic properties. Test methods for measurement of  the electrical resistance through a material (vertical resistance)

This standard does not apply to specify the protection against electrical stresses

The electrodes are placed on opposite surfaces of the test material. Apply a DC voltage to the electrodes and determining the electrical resistance of the tested material

 

EN 1149-3 Electrostatic properties. Test methods for measurement of charge decay

The test methods are applicable to all materials, including homogeneous materials and heterogeneous forms of fibre materials with conducting surface and / or conductive fibres with conductive fibre core.

Charging by induction:The burden of the test sample is performed by inductive effect. Immediately below the test sample, which remains horizontal and no contact with it, an electrode is placed in the field. The field electrode is subjected to high voltage abruptly. If the sample is conductive or contain conductive elements is induced on it a charge opposite to the field electrode. Electrode field incident on the conductive elements does not cross the sample and the resulting field is reduced in a manner that is characteristic of the material tested. This effect is measured and recorded by behind of the sample with a probe of appropriate action.

The resulting field measured by the probe-mediated decreases the load induced on the sample size increases. This reduction of field is used to determine the time of semi-dissipation and protection coefficient

 

EN 1149-5 Electrostatic properties. Material performance and design requirements

This standard specifies requirements for materials and design of protective clothing with electrostatic dissipation, used as part of a complete set grounded to avoid incendiary discharges. These requirements may not be sufficient in flammable atmosphere rich in oxygen. This European Standard is not applicable for protection against voltage.

Equipment requirements:

An electrostatic dissipating material must meet at least one of the following requirements:

– t50 < 4s or S > 0.2 tested according to EN 1140-3 Method 2 (induction charging)

– surface resistance equal to or less than 2.5 x 10⁹ Ω in at least one of the surfaces tested according to the norm EN 1149-1

EN 1149-1:2006 – Test method for measurement of surface resistivity

The standard specifies a method for testing materials to be used in the manufacture of electrostatic dissipative protective clothing (or gloves) intended to avoid incendiary discharges.

It does not apply for materials for clothing or gloves designed to protect against electrical hazards (mains voltages)

The test consists in measuring the resistance of a fabric specimen when it is placed on a insulating base plate and an electrode assembly (cylindrical and ring) is rested upon its surface.

A potential of (100 ± 5) V is applied and after (15 ± 1) s the resistance of the fabric is measured using an ohmmeter.If the resistance is measured to be less than 10⁵ W a lower voltage must be applied and the value recorded in the test report.If necessary, vertical resistances of less than 10⁵ W can be determined by measuring the current with a suitable ammeter connected in series with the specimen and calculating the ratio between the applied potential and current.Repeat this procedure on another 4 specimens or on 4 different points of the garment.

 

EN 1149-2:1997 – Test method for measurement of the electrical resistance through a material (vertical resistance)

The standard specifies a test method for measuring the vertical electrical resistance of materials used for protective clothing.It does not apply for protection against mains voltage.The test consists in placing electrodes on opposite surfaces of the material tested and applying a D.C. potential to the electrodes.The vertical resistance of the test material is then determined.

4 – coaxial connection cable
8 – connector
11 – socket

A potential of (100 ± 5) V is applied and after (15 ± 1) s the resistance is determined using an ohmmeter or electrometer. If the vertical resistance is measured to be less than 105 W a suitably low voltage can be applied and the value recorded in the test report. If necessary, vertical resistances of less than 105 W  can be determined by measuring the current with a suitable ammeter connected in series with the specimen and calculating the ratio between the applied potential and current. Repeat this procedure on another 4 specimens or on 4 different points of the garment.

EN 1149-1:2006 – Test method for measurement of surface resistivity   The standard specifies a method for testing materials to be used in the manufacture of electrostatic dissipative protective clothing (or gloves) intended to avoid incendiary discharges. It does not apply for materials for clothing or gloves designed to protect against electrical hazards (mains voltages) The test consists in measuring the resistance of a fabric specimen when it is placed on a insulating base plate and an electrode assembly (cylindrical and ring) is rested upon its surface. A potential of (100 ± 5) V is applied and after (15 ± 1) s the resistance of the fabric is measured using an ohmmeter. If the resistance is measured to be less than 105 W a lower voltage must be applied and the value recorded in the test report. If necessary, vertical resistances of less than 105 W can be determined by measuring the current with a suitable ammeter connected in series with the specimen and calculating the ratio between the applied potential and current.Repeat this procedure on another 4 specimens or on 4 different points of the garment.   EN 1149-2:1997 – Test method for measurement of the electrical resistance through a material (vertical resistance) The standard specifies a test method for measuring the vertical electrical resistance of materials used for protective clothing. It does not apply for protection against mains voltage. The test consists in placing electrodes on opposite surfaces of the material tested and applying a D.C. potential to the electrodes. The vertical resistance of the test material is then determined. A potential of (100 ± 5) V is applied and after (15 ± 1) s the resistance is determined using an ohmmeter or electrometer. If the vertical resistance is measured to be less than 105 W a suitably low voltage can be applied and the value recorded in the test report. If necessary, vertical resistances of less than 105 W  can be determined by measuring the current with a suitable ammeter connected in series with the specimen and calculating the ratio between the applied potential and current. Repeat this procedure on another 4 specimens or on 4 different points of the garment.    EN 1149-3:2004 – Test methods for measurement of charge decay The standard specifies methods for measuring the dissipation of electrostatic charges from the surface of materials for garments. The test methods are applicable to all materials, including homogeneous materials and inhomogeneous materials with surface conducting fibres and core conducting fibres. Test method 1 (Tribo-charging) A charge is achieved by rubbing the test material directly against cylindrical rods mounted on a moving vertical slide. The electric field generated on the test material by the charge is observed and recorded using an electric field meter connected to a graphic recording device. Calculating and expressing the results Calculate the mean of the absolute values of the maximum force field E0 and the mean of the absolute values of the force field after 30 s E30 for the following groups: a) three measurements made in the warp or machine direction with HDPE rods; b) three measurements made in the weft or cross direction with HDPE rods; c) three measurements made in the weft or cross direction with aluminium rods; d) three measurements made in the warp or machine direction with aluminium rods. Test method 2 (Induction charging) Charging of the test specimen is carried out by an inductive effect. An electrode is immediately placed beneath the horizontally positioned test specimen without direct contact. A high voltage is rapidly applied to the electrode. If the material is conductive, or contains conductive elements, charges of opposite polarity will be induced on the specimen. The fields originating from the electrodes which impact the conductive elements must not pass through the test specimen and the net field is reduced so as to become characteristic of the test material. This effect is measured and recorded behind the sample using a suitable field measuring tube. The increase in the charge induced on the sample is recorded as the net field calculated by measuring the decrease in the tube. This decrease in the field is used to determine the charge half decay time and protection factor. Calculating and expressing the results Calculate the mean value of the half decay time t50 and protection factor S In the case of materials that do not show a protective effect, ER will be equal to Emax. In the case of materials with some protective effects, ER will be less than Emax. A transient peak may occasionally occur at the start of the recorded trace. When calculating ER, such peaks should be ignored. If ER < Emax/2, t50 is recorded as < 0.01 s. If the field indicated did not show decay at Emax/2 within 30 s, t50 is recorded as > 30 s.   EN 1149-5: 2008 Protective clothing – Electrostatic properties – Part 5: Material performance and design requirements This European Standard specifies material and design requirements for electrostatic dissipative protective 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 European Standard is not applicable for protection against mains voltages. The standard specifies 3 areas 1) Performance requirements of materials 2) Design requirements 3) Marking & guidance   TEST                          METHOD                   REQUIREMENTS Surface Resistance    EN 1149-1                   must be less than 5 x 1010 ohms Induction charging      EN 1149-3,-2              Half decay time < 4 s or Shielding factor > 0.2