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EN 13832:2018 – footwear protecting against chemicals
Highlighting the requirements of this important standard.
Image © iStockphoto.com | BenDC
There are a number of industries, such as those involved in the production of chemicals and fuel, that require certain employees to wear footwear that provides protection against hazardous chemicals. EN 13832:2018 is the current version of the European standard to assess footwear claimed to protect against chemicals. The most recent revision of this standard contained some substantial updates that are relevant to manufacturers and suppliers of this footwear. The relevant requirements for this standard are outlined in this article.
EN 13832:2018 is separated into three parts. EN 13832:2018 part 1 outlines the terminology and test methods for footwear protecting against chemicals. Part 2 defines the requirements for limited contact with chemicals and part 3 defines the requirements for prolonged contact with chemicals.
In addition to the chemical protection requirements, the footwear must also comply with the relevant clauses in either EN ISO 20345:2022, EN ISO 20346:2022 or EN ISO 20347:2022. As part of these requirements, the footwear also needs to be chemically innocuous. This means that it must not, in the foreseeable conditions of normal use, release or degrade to release substances generally known to be harmful.
An important inclusion within the 2018 version of this standard was the introduction of new footwear types ‘Type U’ and ‘Type US’ and the establishment of separate test methods determined by whether the footwear is intended for short or prolonged exposure to chemicals. Type U is for footwear claiming to provide protection against splashing of chemicals on the upper only, whereas Type US footwear is intended to protect the wearer from splashing of chemicals on the upper and contact with chemicals on the outsole. Samples of finished footwear must be supplied to laboratories to assess protection against exposure to chemicals.
The intention of EN 13832:2018 parts 2 and 3 is to determine the footwear’s resistance to chemical penetration and chemical degradation for limited or prolonged contact with chemicals. To carry out the required testing, test specimens can be prepared from the upper or outsole from the finished footwear, or from purpose-made testing plaques where sampling is not possible.
For Class I footwear (as defined in EN ISO 20345:2022, EN ISO 20346:2022 or EN ISO 20347:2022), only the outer material is tested – any lining, padding or other materials must be removed. For Class II footwear (as defined in EN ISO 20345:2022, EN ISO 20346:2022 or EN ISO 20347:2022), linings should be removed only if it is possible to do so without damaging the upper. If this cannot be achieved, the lining material may be left in place. To prepare specimens from the outsole, any tread pattern must be removed by splitting or abrading and the thickness of the specimen reduced to between 1.8 mm and 2.5 mm.
Due to the nature of the test specimens required (120 mm in diameter), larger sizes of footwear are preferred due to ease of sample preparation.
EN 13832 parts 2 and 3 contain a standard list of 20 chemicals found within table 4 from which chemicals must be chosen for testing to claim protection against this standard (see table 1).
Requirements for limited contact with chemicals (EN 13832-2)
EN 13832-2 is applicable to footwear intended to come into contact with chemicals for a limited period of time. This period is defined in the standard as ‘continuous or intermittent contact with chemicals for up to one hour’.
To meet the requirements of this standard, two chemicals from those listed in table 1 are required to achieve no major defects, no penetration inside the footwear, and no spilt liquid to be trapped when tested in accordance with EN 13832-1 Clause 4.2 – ‘splashing resistance’. Splashing resistance is required on all footwear (that is, both Type U and Type US). This test method involves filling the footwear with an absorbent medium and pouring 130 ml of the challenge chemical over the shoe, including all sides.
Each chemical is assessed on an unworn pair of shoes that had not previously been tested against any other chemical. The test area is determined by height, as defined in EN ISO 20345:2022, as this is the minimum height below which the requirements of the upper must be fulfilled. The test specimen is visually assessed for liquid penetration and any damage immediately after exposure to the chemical. Further visual assessments are performed at ten minutes, one hour and 24 hours after the initial test. All testing is carried out on unworn and previouosly untested footwear for each challenge chemical.
Degradation assessment is required only on Type US footwear, and it is mandatory to be performed on both the upper and outsole of the footwear. Degradation testing involves exposure to the challenge chemical for a period of 8 hours ±15 minutes, followed by a visual assessment and some physical testing to determine how the footwear has degraded after contact with chemicals. The tests to be carried out are summarised in table 2.
|Table 1: List of test chemicals included in EN 13832-2 and 3:2018|
|Code letter||Chemical||CAS number||Class|
|E||Carbon disulphide||75-15-0||Sulphur containing organic compound|
|H||Tetrahydrofuran||109-99-9||Heterocyclic ether compound|
|K||40% Sodium hydroxide||1310-73-2||Inorganic base|
|L||96% Sulphuric acid||7664-93-9||Inorganic mineral acid, oxidising|
|M||65% Nitric acid||7697-37-2||Inorganic mineral acid, oxidising|
|N||99% Acetic acid||64-19-7||Organic acid|
|O||25% Ammonium hydroxide||1336-21-6||Organic base|
|P||30% Hydrogen peroxide||7722-84-1||Peroxide|
|R||Sodium hypochlorite (13 ±1%)
|S||40% Hydrofluoric acid||7664-39-3||Inorganic mineral acid|
The test methods are denoted by EN ISO 20344:2021 (which relate to the standards EN ISO 20345:2022, EN ISO 20346:2022 and EN ISO 20347:2022) which detail methods dependent on the upper material (for example, leather, rubber or polymeric). Elongation at break (see figure 1) is carried out only on upper material from Class II footwear with a removable lining.
|Table 2: Tests for basic properties of the outsole and upper after degradation – specified in EN 13832-2 and 3:2018|
|Tear resistance (EN ISO 20344:2021, Clause 6.3)
Elongation at break (EN ISO 20344:2021, Clause 6.4)
|Tear resistance (EN ISO 20344:2021, Clause 8.3)
Hardness (EN ISO 868:2003)
Testing required for outsole material includes tear resistance and a measurement of hardness following the procedure in EN ISO 868:2003. This requires the degraded specimen to be cut and arranged into multiple layers in order to achieve the minimum thickness requirement of the hardness test.
There are also requirements for outsole abrasion resistance, but this is not tested after degradation and the requirements are more lax than those given in EN ISO 20345, EN ISO 20346 and EN ISO 20347. An additional 100 mm3 volume of abraded material is permitted than in those standards.
The physical testing is carried out both before and after degradation (on separate test specimens) in order to assess any change in performance after exposure to the chosen chemicals.
The minimum requirements for tear resistance of outsole material and upper material for Class I footwear are defined in EN ISO 20345:2022 Clause 5.
The minimum requirements for both tear resistance and elongation at break of upper material for Class II footwear is that the test results after degradation must be no less than 80 per cent of the value obtained from the unexposed material. The hardness requirement for soling material is that the change in hardness shall be no more than ±10 Shore A units and, in any event, the hardness shall not be less than 30 Shore A.
It should be noted that samples that have been too strongly affected by the degradation test are not to be tested in accordance with Clause 126.96.36.199 (physical testing after exposure). For instance, when test specimens have holes, are swollen and distorted or have become brittle.
The property of water resistance, which is optional in EN ISO 20345:2022, becomes mandatory in EN 13832-2:2018 for footwear protecting against limited contact with chemicals, but with the same performance requirement. In terms of upper style, low shoes are not permitted.
Requirements for prolonged contact (EN 13832-3)
Part 3 of the standard specifies the requirements for footwear intended to come into prolonged contact with chemicals, this is defined as ‘contact for more than one hour’. Footwear for use in prolonged contact with chemicals must be classified as Class II footwear as defined by Clause 4 of EN ISO 20345:2022, EN ISO 20346:2022 or EN ISO 20347:2022 – that is, an all-rubber (entirely vulcanised) or all-polymeric (entirely moulded) boot. Additionally, low shoes and ankle boots are not permitted.
EN 13832-3 requires both permeation and degradation testing to be carried out against three chemicals from table 1. Degradation is carried out on both the upper and the outsole of the footwear to the same method as listed in EN 13832-2 (see table 2). However, under part 3 of the standard, the chemical exposure is 24 hours instead of eight hours, and it is required against at least three chemicals rather than at least two for footwear with limited contact with chemicals. The requirements for the physical testing are also the same as in EN 13832-2. However, it should be noted that only the requirements for Class II footwear will apply and, of course, the test is effectively more severe because of the three times longer exposure.
Permeation testing is a method of determining a material’s resistance to chemicals and a performance level to which this material protects the wearer. This is performed by measuring the rate at which a chemical permeates through the footwear material by a suitable detection method. The test method for this is EN 16523-1:2015+A1:2018. This involves placing a test specimen into a permeation cell with the challenge chemical on one side of the cell and a means of detection on the other. Permeation performance levels are based on the recorded breakthrough time of the chemical. This is detailed in table 3.
|Table 3: Permeation performance levels defined in EN 13832-3|
|Measured breakthrough time (min)||Permeation performance level|
|Between 121 and 240||1|
|Between 241 and 480||2|
|Between 481 and 1440 (more than 8 h)||3|
|Between 1441 and 1920 (more than 24 h)||4|
|>1920 (more than 32 h)||5|
|Performance level 1 is required for a minimum of three chosen test chemicals.|
The permeation testing is carried out in triplicate and the test specimens are prepared from the weakest point of the footwear, which is generally the upper. In the case of multiple construction or irregular design, three specimens are to be tested from each area.
As with EN 13832-2:2018, there is a requirement for outsole abrasion resistance (tested without degradation exposure). However, there is no requirement for water resistance, which is now covered by the mandatory need for the footwear to be Class II.
EN 13832:2018 is relevant to all footwear that comes into contact with chemicals. This standard separates and defines the requirements for short-term (less than one hour) and long-term (more than one hour) exposure to chemicals. It also details test methods, including splashing resistance and variable exposure times for degradation resistance. Type U and Type US footwear are defined in this standard, with Type U providing splash protection from the upper and Type US providing splash protection from the upper and contact protection from the outsole.
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