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EN ISO 374-1:2016 chemical glove requirements

Investigating the revised requirements for gloves offering chemical protection.

Many modern industrial processes involve the use of highly concentrated and dangerous chemicals. This fact, combined with the almost daily announcements about potential health effects caused by long- or short-term exposure to chemicals that were once considered to be safe, means there is an ever-increasing need to minimise our contact with any substance that may have an adverse reaction to human health. Working safely with these hazardous materials requires adherence to strict safety procedures and the use of specially designed protective equipment. In terms of splashes and spills from liquid chemicals, the hands of the worker can be of particular concern. Therefore, specialist gloves have been developed to protect against exposure to chemicals.

The level of protection against chemicals provided by a particular glove will depend not only on the construction of the glove (including its length and freedom from holes), but also the choice of materials used to produce the glove, as it needs to be resistant to the chemicals against which protection is required.

The materials used in suitable gloves protect the hand and lower arm by preventing the chemicals from reaching the inside of the glove. To be effective, each material must not only resist the passage of the chemicals through its structure – termed 'permeation' – but must also resist degradation by the chemicals that would lead to such damage as cracking or holing.

 

Figure 1: Testing a glove for air leakage by immersing in water in accordance with EN 374-2

A European standard for gloves protecting against chemicals was first published in 1994 as EN 374-1, and was subsequently revised in 2003. The current revision of this standard is EN ISO 374-1:2016. This standard contains the terminology and performance requirements for chemical protective gloves. There are various changes between the 2003 version of EN 374-1, and the current EN ISO 374-1 version. One of the major changes is in addition to penetration and permeation testing, degradation testing is mandatory for all chemical protective gloves (for more details, please see the article 'EN 374-4 degredation testing of gloves'). However, the obligation to test chemical protective gloves for mechanical properties in accordance with EN 388 has been removed. This is now optional for gloves manufacturers who wish to claim both chemical and physical protection in their product. This article will guide manufacturers through the requirements of the new EN ISO 374-1 standard, and detail how SATRA can help with both testing and certification needs.

 

Figure 2: Flask pictograms for type A, B and C gloves, showing tested chemicals identified by their code letters

Penetration

All chemical protective gloves shall not leak when tested in accordance with EN 374-2. Leakage can occur through imperfections in a glove, such as pinholes or failures in a seam. The EN 374-2 test consists of two parts – air and water leak testing. For the air leak test, the glove is immersed in water and its interior is pressurised with air (figure 1). A leak is detected by a stream of bubbles from the surface of the glove. A similar principle is applied to the water leak test. In this assessment, the glove is filled with water and any leaks are detected by the appearance of water droplets on the outside surface of the glove.

Permeation

Permeation is the process through which chemicals move through a glove at a molecular level.

The permeation test involves exposing the outer surface of the sample to the test chemical in a two-part cell, while circulating an inert gas or liquid through the other part of the cell (figure 2). During the test, the amount of test chemical that permeates through to the inert collecting medium is measured until a predetermined permeation rate is reached. The time for this to occur (known as the 'breakthrough time') is recorded. This determines the material's performance level. Which chemicals are tested will depend upon the end-use of the glove and what marking category the manufacturer wishes to obtain.

EN ISO 374-1 lists 18 chemicals (see table 1), but other chemicals and mixtures can also be tested, depending on the application of the glove.

Table 1: List of test chemicals specified in EN ISO 374-1:2016
Code letter Chemical CAS number Class
A Methanol 67-56-1 Primary alcohol
B Acetone 67-64-1 Ketone
C Acetonitrile 75-05-8 Nitrile compound
D Dichloromethane 75-09-2 Chlorinated paraffin
E Carbon disulphide 75-15-0 Organic compound containing sulphur
F Toluene 108-88-3 Aromatic hydrocarbon
G Diethylamine 109-89-7 Amine
H Tetrahydrofuran 109-99-9 Heterocyclic and ether compound
I Ethyl acetate 141-78-6 Ester
J n-heptane 142-82-5 Saturated hydrocarbon
K 40 per cent Sodium hydroxide 1310-73-2 Inorganic base
L 96 per cent Sulphuric acid 7664-93-9 Inorganic mineral acid
M 65 per cent nitric acid 7697-37-2 Inorganic mineral acid
N 99 per cent acetic acid 64-19-7 Organic acid
O 25 per cent ammonium hydroxide 1336-21-6 Organic base
P 30 per cent hydrogen peroxide 7722-84-1 Peroxide
S 40 per cent hydrofluoric acid 7664-39-3 Inorganic mineral acid
T 37 per cent formaldehyde 50-00-0 Aldehyde

Three test specimens are taken from the palm of the glove. For gloves longer than 400mm, and where the cuff is also claimed to provide protection, another three test specimens are also taken from the cuff. If the glove contains a join or seam in the hand area, this must also be tested.

Test results are reported based upon the normalised breakthrough time achieved. There are six permeation performance levels (see table 2). The highest level of protection is level 6, which shows a breakthrough time of greater than 480 minutes.

Table 2: Classification of permeation performance levels
Measured breakthrough time (min) Permeation performance level
>10 1
>30 2
>60 3
>120 4
>240 5
>480 6

Testing is carried out in accordance with EN 16523-1, which has replaced EN 374-3. Inside a cell, the surface of the glove material is placed in direct contact with the challenge chemical and the back of the glove material is in contact with the collecting medium. As such, the glove material is acting as a barrier separating the challenge chemical from the collecting medium. The amount of chemical which permeates through the glove material into the collection medium is measured, and from this the breakthrough time is calculated.

 

Assessing glove material by exposing it to a test chemical in a two-part cell

Degradation

Degradation is the process through which a change to a material occurs – in this case, through contact with a chemical. Indications that degradation has occurred include flaking, swelling, change in appearance, and hardening of the material tested.

Assessing the degradation of glove materials is new to EN ISO 374-1. Degradation shall be determined for each of the chemicals claimed in the user instructions, and on the marking. Testing shall be carried out in accordance with EN 374-4. If a protective glove is longer than 400mm in length, and permeation testing has been carried out on both the cuff and the palm, degradation testing shall at least be carried out for the area which achieved the lowest permeation result. The principle of the test is that a change in puncture resistance of the material is measured after continuous contact of the external surface with a challenge chemical. The force required to push a stylus through the glove material is measured, both before and after exposure to the challenge chemical.

Marking

The marking of chemical gloves (see figure 2) shall be in accordance with EN 420 and the specific requirements given in EN ISO 374-1. There are three types of chemical protective gloves:

Type A gloves have achieved level 2 or greater against six of the chemicals listed in EN ISO 374-1 (see table 1). As a minimum the six tested chemicals shall be identified by their code letters under the flask pictogram.

Type B gloves have achieved level 2 or greater against at least three of the chemicals listed in EN ISO 374-1. The tested chemicals shall be identified by their code letter under the flask pictogram.

Type C gloves have achieved at least a level 1 against one of the chemicals listed in EN ISO 374-1. Reference to the standard EN ISO 374-1 shall be given for each of the three categories, as well as listing the glove type. If chemicals not listed in EN ISO 374-1 have also been tested, these can be detailed in the user instructions.

User Instructions

User instructions in accordance with the requirements given in EN 420 must be supplied by the manufacturer. In addition, chemical glove user instructions shall include the results for penetration, degradation and permeation testing. There should be a list of all the chemicals against which the gloves have been tested, in addition to the performance levels for permeation testing.

There are a number of specific warnings that should be highlighted, including drawing the user’s attention to the fact that the level of chemical resistance may be different if the chemical is used in a mixture.

If the gloves are intended to be reused, then instructions must be provided for decontamination. If no information is given regarding decontamination, it must be stated in the user information that the glove is for single use only.

How can we help?

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SATRA is one of Europe's foremost Notified Bodies for EC and EU type-examination of gloves. We have a dedicated team of assessors to guide you through the certification process, as well as fully equipped physical and chemical laboratories. SATRA’s chemical laboratory has an extensive range of detection techniques for permeation testing, which can be used to test for many more than the 18 challenge chemicals listed in EN ISO 374-1. Please email chemistry@satra.com for more information.