Normatives references
- 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 Ω a lower voltage must be applied and the value recorded in the test report.
If necessary, vertical resistances of less than 105 Ω 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.
- EEN 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 (Tribocharging)
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:
- three measurements made in the warp or machine direction with HDPE rods;
- three measurements made in the weft or cross direction with HDPE rods;
- three measurements made in the weft or cross direction with aluminium rods;
- 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.
- prEN 1149-5:2005 – Performance requirements (will replace European standard EN 1149-1:1995)
Editor’s note. – The antistatic performance requirements for clothing and gloves were contained in the previous “harmonised” European standard EN 1149-1:1995, which was used for the type certification of PPE (assumption of conformity).
At the time this note was written, EN 1149-1:1995 was no longer applicable and the draft standard EN 1149-5:2005 had not obtained unanimous approval during the various voting sessions (it can thus not be considered to represent a sustainable document for PPE certification procedures, which will have to refer solely to E.D. 89/686/EEC).
The (draft) standard specifies the requirements for electrostatic dissipative protective clothing designed to avoid incendiary discharges.
The requirements may prove to be insufficient in oxygen-enriched inflammable atmospheres. The standard does not apply for protection against mains voltage.