Published: 22nd Sep 2014
With a focus on chemical and flame resistance, Alberti Gabriella Fusi discusses the requirements for CE marking of protective clothing .
Safety clothing is a widespread topic. The most frequent concern is to avoid the use of products that could contain hazardous substances. While it is right to worry about such problems, safety stretches far beyond this one aspect.
There are certain products, such as Personal Protective Equipment (PPE), whose safety claims must be guaranteed by CE marking. These markings are regulated by European Community Rules and Directives and adopted at national levels with specific laws. The characteristics of such items must be documented through tests that ensure conformity to the safety requirements defined in the relevant directives.
The clothing industry is regulated Directive 89/686/CEE, adopted in Italy through the decreto legislativo (DLgs) 475 1992.
The following are considered PPE: • Protective clothing worn by workers exposed to, for example, chemicals on oil platforms • Suits that civil protection and firemen must wear approaching and fighting fires • High visibility clothing used to signal the presence of the wearer in various lighting conditions including under vehicle lights
PPE is divided into three categories according to the protection level offered. For the first and the third categories the conformity and the relative authorisation must be attested by a notified organisation.
For Category I PPE there is no action on the part of the notified organisation that guarantees the compliance. Category I PPE is considered to be of simple design, where the designer supposes the end user can directly evaluate the effectiveness against the minimal risks whose effects, if gradual, can be felt before harm is caused.
The PPE in Category I is designed to protect the wearer against: mechanical harm with superficial effects; mild cleaning products; risks from handling items no hotter than 50 °C, harmful impacts; common atmospheric agents; light impacts and vibrations; and solar radiation.
For Category II PPE the compliance of the PPE model must be evaluated and attested by a notified organisation following the procedure detailed in article 10 of the Directive. Into this category falls all PPE belonging to neither Category I nor III.
For Category III PPE, the compliance of PPE must be evaluated and attested by a notified organisation, following the procedure detailed in article 10 of the Directive. PPE production must be subject to control from the notified organisation according to one of the supervision procedures listed in article 11 of the Directive.
Category III PPE is considered to be of complex design and is intended to protect against hazards that are life threatening or that can seriously and permanently harm the operator’s health, particularly when the designer thinks the user can’t promptly recognise the immediate risks.
PPE in Category III includes: filtering and complete isolation respiratory protective equipment; temporary protection against chemical aggression or ionising radiation; equipment to operate in environments hotter than 100 °C and colder than -50 °C; protection from falls from heights; protection from electrocution.
Accreditation and notification
The CE guidelines 765/2008 of the European Parliament and Council of 9 July 2008 introduced considerable innovations regarding the accreditation and market surveillance relevant to product commercialisation.
The organisations authorised to issue the EC type examination certificates before the EC notification from their member state must be accredited. All the European notified organisations are recorded on the Nando database (New Approach Notified and Designated Organisations), which stores the identification number for the organisation and the scope of the notification.
Synergising safety and comfort
PPE is, as mentioned earlier, the subject of specific legislation with regards to both its placement on the market and its use.
Not only is the requirement for safety fundamental, but as far as possible PPE should not affect the comfort of the user. Safety and comfort must be objectively demonstrated by testing selected criteria on the basis of European standards. These tests conducted should be in accordance with the proposed application of the device.
Ensuring the synergy of comfort and safety becomes more difficult as the level of risk against which the PPE must protect increases.
The human body needs to maintain a constant core temperature of 37.5 °C and so to achieve this, the production of metabolic heat must equal the heat losses that occur through the mechanisms of radiation, convection, conduction, and sweat evaporation.
The critical environmental conditions in which a worker performs high risk jobs will impact upon this exchange. As an example, work conducted in high temperature environments without adequate heat exchange systems would create very serious risks. The body temperature would rise, accompanied by a considerable loss of liquids through sweating. The combined factors of working in the heat would lead to dehydration, thermal stress and loss of concentration. The most extreme cases of such unbalance are found in firefighting activities.
Whether designing or purchasing PPE for industrial firefighting or heated environments, it is of great importance to consider:
• Guaranteed protection from fire and heat through strong insulation capacity • Avoiding excessive thermal stress through strong heat dissipation characteristics
Keeping in mind that heat and fire protection PPE falls into Category III, which offers protection against lethal and severe injuries, the protection must provide fireproof characteristics throughout all its components: not only the external layer, but also the lining, cuffs, padding, Velcro, zips, seams and yarns.
Assessment of the PPE’s protection is evaluated through a series of tests conducted on brand new samples, as well as tests after a series of washing cycles to ensure the retention of the performance during everyday use and maintenance.
Heat and fire protective clothing must:
1. Be fire resistant for the duration of its use without dripping or melting. Reference parameters are the limit oxygen index (LOI) and limited flame propagation, which are evaluated following the guideline EN ISO 15025.
2. Oppose itself to heat transmission, so as to avoid an increase of internal temperature. The relevant parameters are heat transmission through flame exposition and radiant heat transmission.
3. Not alter its characteristics from heat exposure in the estimated use limits.
4. Provide adequate mechanical resistance.
It is wrong to assume that providing the greatest protection against fire will inevitably lead to the loss of comfort. Comfort is a fundamental requirement, without which the protective and operational characteristics alone would not be sufficient to ensure the correct use of the PPE.
Generally speaking, worker comfort and wellbeing are derived from the weight of the equipment, the ease with which it allows workers to perform the necessary movements, and the ability to allow for a proper thermal equilibrium.
Evaluating the impact of clothing on comfort and wellbeing is complex, but can be divided into two main aspects:
• Thermo-physiologic contribution - ascribable to heat and humidity transport • Sensory contribution - subjective feelings regarding wearing the item
For this reason, beyond the tests already mentioned, another series of tests is also significant, with some foreseen by the official regulation.
Some tests evaluate the level of comfort by simulating the absence of physical stress, while others simulate stressing conditions. Below is a brief summary of the evidence needed.
Thermo-physiologic comfort in stationary conditions:
1. Water vapour resistance (RET) is necessary to evaluate breathability.
This test is of fundamental importance for the assessment of the body’s thermoregulation and the suitability of the protective clothing. The value of RET is expressed as M2PA/W in the terms of purchasing, and it is usually≤ 13 M2PA/W. The humidity transport is greater the lower the value of RET.
2. Thermal resistance (RTC) evaluates the thermal insulation of a fabric. The greater the value of RTC the greater the thermal insulation. It is essential to know the environmental conditions of use of the product - in warm environments in the insulation should be as low as possible, whereas in a cold environment the opposite is true.
Thermo-physiologic comfort in conditions of physical stress:
1. Buffering index rates the resistance to the transfer of liquid (sweat) from the skin to the environment offered by the textile, through the determination of the absorption and release of water in the environment index (la,r) and the water release to the environment index (lr).
2. Drying time determines the time required by a wet fabric to recover the thermal resistance characteristics it has in standard conditions.
Sensory comfort, as rated through a test bundle:
• Surface friction strength evaluates the mechanical interaction between the moist skin and the fabric
• Superficial woolliness index evaluates the sensation given on the skin by the wholeness of the fabric - a fabric too smooth in case of sweat has the tendency to uncomfortably stick to the skin, while a fabric too woolly may give an itching sensation
• Water absorption time evaluates the fabric’s hydrofilicity, meaning its ability to absorb sweat through different processes such as absorption, desorption and capillarity
• The fabric’s ability to absorb liquid is not only a function of its structure and physical-chemical composition, but it is also affected by surfaces and finishing treatments
• Folding angle evaluates the stiffness of the sample and gives a dressability rating to the clothing
The case of chemical hazards
Speaking of protective devices without citing protection against chemical hazards would be to misjudge an extremely critical problem. As awareness increases as to the damage that chemicals can cause, this has highlighted the global prevalence of chemical exposure scenarios.
It is not correct to think that the only way to deal with problems is to remove the chemicals, as this would underestimate, for example, the advances in the medical and pharmaceutical fields. In any case, there are many working environments in which removal of the hazard is not possible.
Protection and prevention are key to ensuring the safety of workers and their working environments.
As will be detailed in the following sections, the laboratory tests to be carried out in order to verify the performances of materials in contact with chemicals include: resistance of the material to liquid penetration and permeation, resistance of clothing to liquid penetration by spray and jet, and determination of inward leakage of aerosol or fine particles into suits.
Resistance of the material to liquid penetration
During the test, a defined volume of liquid is applied on the surface of the tested sample. The amount of liquid that penetrates the material and the amount that is repelled allows specific indexes to be calculated, to determine the performance of the material in protecting against liquid penetration.
Resistance of the material to liquid permeation
Permeation is the process by which a chemical compound spreads at the molecular level throughout protective clothing. During the test the sample used for the protective clothing is used as a barrier between two chambers, one filled with the testing chemical agent and the other containing the sampling probe. The probe is then quantitatively analysed to find out the concentration of chemical product and therefore the quantity of it that has permeated the barrier as a function of time after the initial contact.
Resistance of clothing to liquid penetration by spray - spray test
During the test a liquid spray containing a fluorescent or coloured marker is aimed under controlled conditions at the protective clothing worn by a test subject. The inspection of the inner side of the clothing and the external surface of the absorbent material worn under the sample clothing allows identification of penetration points of the liquid.
Resistance of clothing to liquid penetration by jet - jet test
The test is similar to the former, in both operational and result evaluation methodology. The only difference is the use of a liquid jet instead of a spray.
Determination of inward leakage of aerosol or fine particles into suits
During the test a reference aerosol, made of particles of sodium chloride, is generated inside a chamber where the test subject, wearing the clothing to be tested, performs a sequence of predefined exercises. The leakage in every position of the suit is measured by flame photometry.
Any working day that involves handling chemicals, working in extreme heat or fighting fires has high stakes. It is essential that workers in these environments are equipped not only with the most suitable protection available, but also the knowledge of how to use and wear their safety apparatus correctly for protection in the face of a hazardous situation. Ensuring protective clothing bears the CE mark is one step closer to achieving a zero harm workplace.
Published: 22nd Sep 2014 in Health and Safety International