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Many workers such as those working in manufacturing, foundries or catering kitchens are exposed to thermal risks whilst undertaking their job. It may not be possible to just remove these thermal hazards and in such circumstances suitable PPE, which may include protective gloves, will need to be provided to the worker to protect them from injury.
The European standard EN 407 – ‘Protective gloves against thermal risks (heat and/or fire)’ has recently been revised by the appropriate European Committee for Standardisation (CEN) technical committee, and published in 2020. This standard is used to assess the degree of protection against thermal risks a glove offers the user. This version of the document supersedes the previous version which was dated 2004 and contains a number of changes, which we will go through later in this article.
This document specifies the glove requirements in terms of performance, marking and user information. It also specifies the test methods and user information requirements for protective gloves and other hand protective equipment claiming protection against thermal risks for professional, consumer and domestic use. This standard doesn’t apply to gloves for fire-fighters or welding as they have their own performance standards. It is used for all gloves and other protective equipment which protect the hands, part of the hand or arm against heat and/or fire in one or more of the following forms: flames, contact heat, convective heat, radiant heat, small splashes of molten metal or large quantities of molten metal.
European PPE regulation
When the European PPE Regulation (EU) 2016/425 was first applied on the 21st April 2018 it replaced the previous legislation (Directive 89/686/EEC) which excluded domestic oven gloves from its scope meaning CE marking was not possible. However, Regulation 2016/425 does include gloves ‘explicitly described and marketed accordingly by their manufacturers for private use to protect against heat’ within its scope. The Regulation clearly defines the obligations and responsibilities of: manufacturers, authorised representatives, importers and distributors of PPE. This newlyadded group of products that must be CE marked when sold in Europe includes: oven gloves, pan holders, gloves for use with barbeques and any other piece of hand protection intended to be used in a domestic setting.
“the 2020 version of the Protective gloves standard contains a single mechanical test requirement for tear resistance and is applicable to all types of gloves”
Hence as part of the review of EN 407 the committee took the opportunity to further develop the standard to include testing methods, performance requirements and a new pictogram for hand protection for the domestic market.
Physical testing
The 2004 version of the standard contained two mechanical test requirements based on tests carried out under EN 388 ‘Protective gloves against mechanical risks’; abrasion and tear resistance. The 2020 version of the standard contains a single mechanical test requirement for tear resistance and is applicable to all types of gloves. The resistance to tear is defined as the force necessary to propagate a tear in a rectangular specimen slit halfway along its length. The test method is contained within EN 407: 2020; although this procedure is equivalent to that contained within EN 388:2016+A1:2018. The standard states that glove material(s) shall be tested and adhere to at least 10 N which is equivalent to the level 1 requirement of EN 388.
In addition to this the 2020 version of the standard contains sizing requirements for the minimum length of gloves that claim protection against small and large splashes of molten metal.
During some task’s gloves may become soiled and may require cleaning. If gloves are intended to be cleaned, the manufacturer will need to supply cleaning instructions to the wearer; whilst demonstrating that the cleaning does not have any significant detrimental effect on the glove’s protective properties. All tests within this standard are performed on unused gloves or hand protective equipment. However, for products that are intended to be cleaned, tests must also be carried out on the products after the required cleaning cycles following the procedures instructed by the manufacturer. For example, if the manufacturer intends the gloves be laundered up to 5 times in a washing machine at 30°C and line dried, they will need testing evidence to support this. Likewise, if they intend the gloves are tumble dried, testing evidence will also be required to support this claim.
Thermal performances
EN 407 specifies six thermal properties each with four associated performance levels which allows manufacturers to create a range of gloves offering differing properties for different requirements. The four performance levels range from Level 1 being the lowest level of protection to Level 4 being the highest level of protection.
To claim performance levels of 3 or 4, for any of the thermal properties, the limited flame spread test must also be performed and must obtain at least a level 3. If this requirement is not met the maximum level that can be reported for any of the thermal properties shall be a level 2.
“the gloves need to burn slowly enough for the wearer to recognise this and safely doff the gloves”
Limited flame spread test
The limited flame spread test is used to assess the ability to protect the wearer’s hand if it comes into close proximity with a naked flame. To give good results in this test the gloves do not need to be inflammable but need to inhibit combustion and burn slowly enough for the wearer to recognise this and safely doff the gloves.
The test consists of the samples of whole gloves held vertically over a test burner with the flame in contact with the end of the middle finger of the gloves or at the longest position for mitts. The flame is bought into contact with the test sample for 10 seconds after which time, the flame is withdrawn and the degree of afterflame and after glowing of the sample is recorded. This test is different
to that contained within the 2004 version of the standard which allowed for two flame exposure times of 3 and 15 seconds. In this latest version of the test, a metal rod is inserted into the glove to prevent the material retracting from the flame.
The standard contains 4 levels of protection based on the duration of time for the after-flame and afterglow. The standard does not permit the innermost surface of the test sample to show any signs of melting, complete holing of the sample or for it to come apart at the seams. These requirements differ slightly to those contained within the 2004 version of this standard with the lowest level of protection being slightly less demanding.
For high thermal resistant gloves (levels 3 or 4), all outer materials different to the finger area shall be tested according to EN ISO 15025:2016, method A and comply at least with level 3. Seams and outer accessories with a surface area greater than 10 cm2 shall also be tested and meet these requirements.
Contact heat
During conduction, heat is transferred within and through physical bodies. During use the wearer of the gloves will be intending to hold a hot item and the heat will transfer through the contact with the gloves and into the wearers hand. Gloves with this type of protection would also be able to protect from any accidental contact such as the back of the hand and the internal sides of an oven.
The amount of heat transferred during conduction depends on many factors: surface area, actual temperature of the hot object, the conductivity and heat capacity of the glove and object and the pressure of the contact. For example, a hot cup of coffee 70°C – 80°C can easily raise a blister because the contact pressure is high to hold it whereas, a spark from a grinder, despite being 1000C plus is barely noticeable, the contact pressure is light and the object is very small with a very low heat capacity.
The test method is EN ISO 121271:2015. Within this test the palm region of all gloves shall be tested along with any other areas that either differ in materials and construction from the palm region or are intended to be exposed to contact heat and provide protection to the wearer. The test sample should include all layers of materials including outer, lining and mid-layer materials but excluding any localised reinforcement. In this test a metal cylinder is heated to the
required temperature; 100 ˚C, 250 ˚C, 350 ˚C or 500˚C and brought into contact with the outer surface of the test sample. A Calorimeter (temperature measuring device) is placed on the underside of the test sample, this replicates where the wearer’s hand would make contact and the threshold time is then measured. The threshold time is the time taken for the temperature to rise to 10˚C above the starting temperature, the levels relate to the temperatures that are being tested. Performance level 1 being the lowest at 100°C and performance level 4 being the highest at 500°C.
Convective heat
Convection is the mechanism of transfer of heat from the source to another place by the movement of fluids such as water or air. Heat transmission through gloves is largely determined by its thickness including any air gaps trapped between the adjacent layers.
In this test the palm region of all gloves shall be tested along with any other areas that differ in materials and construction from the palm region, and are intended to be exposed to contact heat and provide protection to the wearer. The samples are exposed to a heat source, a flame which itself is composed of hot turbulent combustion gases.
The test method is EN ISO 9151:2016 and the thermal insulation of the glove is measured by the rate of temperature rise of a calorimeter on the inside of the glove while the glove outer is placed in contact with a controlled gas flame. The 4 levels within this test are based on the heat transfer index, this is the rate at which the temperature can rise by a specified amount in a specified amount of time.
Radiant heat
Heat will transfer between physical bodies which may be separated spatially through thermal radiation in the form of electromagnetic waves in the infra-red spectrum in all directions from the hot body. The intensity of the radiation (characterised by the heat flux density) will influence the degree of transfer that occurs and also depends on the distance from the object according to an inverse square law. Radiant heat from hot bodies can be very intense and is invisible. It can result in injury or even spontaneous ignition long before any conductive contact is made with the source (e.g. magnifying glass and the sun).
The testing is carried out in accordance with method B of EN ISO 6942:2002 with a specimen supported in a free-standing frame and exposed to a specific level of radiant heat. The times for temperature rise of 12˚C and 24˚C in a calorimeter are recorded and are expressed as radiant heat transfer indexes. The percentage heat transmission factor is calculated from the temperature rise data.
Small splashes of molten metal
This test is used to assess the degree of protection offered to the wearer’s hand from being struck by drops of molten metal such as during metal grinding. In most circumstances where gloves give good results the droplets of molten metal do not stick on the surface of the test sample but tend to run off the sample, hence significantly reducing the time in which they are in contact and not raising the temperature of the test sample.
The testing is carried out in accordance with EN 348:1992, the thermal insulation of the glove is measured by the rate of a temperature rise of a calorimeter placed on the underside of the test sample. Drops of molten metal of a specified size (0.5g) impact the glove outer at a defined rate. The number of droplets which produce a temperature rise of 40 °C shall be measured. The 4 levels of protection from small splashes of molten metal are based on the number of droplets of molten metal applied. Following testing the outermost and innermost layers of the glove shall be inspected, it shall show no sign of melting and no hole shall appear in the innermost layer.
Large quantities of molten metal
If testing to this clause the use of molten iron is mandatory. Although other optional molten materials such as aluminium or molten glass may be tested as required and the corresponding test results shall be given on the information supplied by the manufacturer.
The test method is according to EN ISO 9185:2007 taking into account conditions given within EN 407. Materials are tested by pouring defined quantities of molten metal onto the test specimen supported at an angle to the horizontal. Following pouring, damage is assessed by visual examination of an embossed thermoplastic PVC sensor film which is placed directly behind and in contact with the test specimen during the test. Any adherence of the test metal to the surface of the glove is also recorded and material assemblies which ignite during the test do not meet the requirement of this test. Folds in the material or seams on the outside of the glove can act as trapping points for the molten metal and the gloves shall be designed to prevent the metal being retained. Material assemblies which ignite during the test do not meet the requirement of this test and innermost layers of the glove shall be inspected, it shall show no sign of melting and holing.
Pictograms
EN 407, like other PPE glove standards, requires the glove to be marked with a symbol (pictogram) showing the performance levels of the standard that have been met. The 2020 version of the standard introduces a second pictogram that is used in place of the pictogram used within the previous version of the standard under certain conditions.
The previously used pictogram (image 1), which incorporates the flame icon, is now used to label a product that claims limited flame spread level of at least a performance level 1. The manufacturer may also claim other properties at the achieved levels. The new pictogram (image 2) is now used to label a product that does not claim limited flame spread. The manufacturer will claim at least one other property up to a level 2. The marking of a product with both pictograms is forbidden.
The level of performance for each property assessed will be reported under the relevant pictogram as shown in image c. If the property is not claimed this will be reported with the inclusion of an ‘X’ in the place of the level numeral.
Outro
Manufacturers who supply gloves which offer any degree of protection against thermal risks will be eager to undertake the necessary testing in order to mark their products in compliance with the 2020 version of the standard.
