KAN Report 39
|Consideration of time-related performance characteristics of PPE in standards, 09/2007, K.-H. Noetel et al. (4 MB)|
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Personal protective equipment (PPE) is worn or carried by a person in order to protect them against potential risks to their health or safety. The protective action of PPE may however deteriorate as a function of the intensity and duration of its use, its care and its storage. The filtration performance of electrostatic filters, for example, particularly against oily, fluid aerosols, has been observed to drop over longer periods in use, and also between uses. This issue prompted the Commission for Occupational Health and Safety and Standardization (KAN) to commission the present study. The BG BAU (the institution for statutory accident insurance and prevention in the construction industry) was assigned the task of conducting the study.
In the study, 186 harmonized PPE standards and 53 draft PPE standards were examined in order to determine the extent to which they address changes in the performance of personal protective equipment and its components as a function of the equipment's age and use. Of the approximately 330 PPE standards and draft standards, standards covering the sport and leisure sector, work performed on live parts of electrical equipment, and protective clothing for the users of manually guided chain saws were excluded from the scope of the study. The assessments are based upon consultations of manufacturers, experts at PPE test and certification bodies, and members of the PPE expert committee.
Overall, the conclusions of the study were satisfactory. The deterioration in the protective action resulting from use or ageing is already largely considered in many standards governing PPE. Nevertheless, a need for revision was observed in some areas, partly as a result of technical developments and new findings.
The study shows that the performance characteristics of PPE which are dependent upon time or use are considered in a number of different ways within standards:
• By direct product requirements
• By requirements concerning the material properties of the PPE
• By specification in test methods
• By marking of the PPE
• By instructions and warnings in the user information
Whereas the first three of these points concern the product directly, the last two concern provisions through which a risk resulting from a deterioration in the protective action can be combated indirectly, or which enable the deterioration to be recognized.
2.1 Time-dependent performance characteristics in product requirements and tests
Time- and usage-dependent performance characteristics are generally difficult to address adequately in a manner suitable for practical application if use is made solely of product requirements in standards. Owing to the infinite possible combinations of influencing factors, such as the form and duration of use, external influences (including UV radiation and weather conditions) and the intensity of their action upon the PPE, predictions of possible impact cannot be made unequivocally.
Standards which address deterioration in performance via product requirements or test methods can be found in all areas of PPE. Selected types of PPE serving as examples are listed below:
In the area of head protection, the ageing behaviour of helmet shells depends in part upon the material used and its resistance to climatic influences such as solar radiation, atmospheric pollution, atmospheric humidity and temperature. These effects are accompanied by mechanical stresses during use or handling of the helmet by the user (duration and location of use, care, storage).
Test requirements therefore involve various forms of pretreatment (high and low temperatures, UV ageing, water, etc.), by which changes in the material properties which could result in deterioration of the PPE's performance are simulated.
Requirements which consider a deterioration in the protective action as a result of usage may be found for example in the standards governing foot protection. Usage is simulated for example on the outsole by its being bent, stretched or elongated. In addition, penetration-resistant inserts, and toe caps manufactured from non-metal materials, are subjected to chemical or thermal ageing prior to testing of the resistance to penetration and to shock respectively. The purpose here is to enable potential negative influences upon the performance and therefore a deterioration in the protective action to be detected.
The prEN ISO 12402 series of standards governing personal floatation devices include minimum requirements for resistance to wear, which are ascertained by drop testing.
2.2 Time-dependent performance characteristics in user information, including marking
If time- or usage-related performance characteristics are not or cannot be addressed directly by product requirements or by provisions in test methods, users must be able to estimate themselves whether the PPE still provides protection.
For this purpose, they require suitable information from the manufacturer indicating how a possible deterioration in the protective action may be ascertained. This need is already largely addressed by the requirements concerning the content of the user information: the information to be provided on areas of use and limits to application, on possible negative affects upon the PPE, and on maintenance and care.
Standards governing eye protection for example require that the user information:
- contain instructions that protective glasses are no longer to be used if the lenses are scratched or damaged;
- state a use-by date or maximum duration of use;
- contain recommendations for maintenance, cleaning and storage.
The factors which influence PPE against falls from a height are so numerous that worst-case stresses can be simulated, but not real-case applications. Other instruments are therefore exploited in the standards for assessment of whether such items of PPE should be discarded. These instruments include user instructions, inspections by competent personnel, inspection of the equipment by the user prior to use, or its decommissioning following a fall. In the opinion of experts, the user should be in a position to assess the protective action of the PPE with the aid of the manufacturer's information. In addition, each item of PPE must bear a manufacturer's batch or serial number or other marking by which it may be traced. This requirement is to enable the user or competent person to obtain information on the product from the manufacturer, such as the date of manufacture.
In the area of "descender devices", too, the user can ascertain the service life from the marking on the equipment. As with PPE against falls from a height, the user is able to assess the protective action of this PPE with the aid of the manufacturer's information.
Standards governing foot protection require that codes of practice, for example concerning the electrical properties, be included with each pair of shoes in addition to the manufacturer's information. The codes of practice include information such as recommendations for use, warnings, and further product information which is important for the user for the proper use of conductive, antistatic or electrically insulated shoes.
2.3 Inadequate consideration of time-related performance characteristics
The standards governing respiratory protective devices do not always give adequate consideration to the possibility of the protective action deteriorating over a period of use. The reason given is that use under real-case conditions cannot be simulated, since respiratory protective devices are subject to a plethora of influences which may impair their protective action. Even though standards attempt to adjust tests and requirements as far as possible to real-case conditions, only limited conclusions are possible regarding the actual effects and therefore the service life.
The standards contain requirements for marking, packaging and user information with regard to time-related performance characteristics. However, this information is of only limited assistance to users of filtering respiratory protective devices for ascertainment of the extent to which the protection offered against polluted atmospheres is still assured once the respiratory protective devices have been in use or storage. Conversely, in the area of self-contained closed-circuit respiratory protective devices, warning devices and the user information enable the user to assess the safe condition of the equipment.
Standards governing hearing protection (EN 352-1 to -3:2002 governing the general requirements of various ear muffs and ear plugs) also fail to deal adequately with changes in performance over time (use and ageing). Marking, packaging and user information in compliance with the requirements of the standard provide users with only a limited basis for assessment of the protective action.
Test methods for protective gloves do not yet give adequate consideration to degradation, which may have a major influence upon the protective action. It must however be considered that use under real-case conditions cannot be simulated. This is due mainly to the numerous factors which may impair the protective action.
The standards contain requirements for marking, packaging and user information with regard to age-related performance characteristics. EN 420 requires the packaging and each glove to be marked with the use-by date if the protective action is substantially impaired by ageing. The user is not, however, fully equipped to judge whether the protective action is still adequately assured following use or storage.
In cases where cleaning may have an influence upon the protective action of protective clothing, whether through shrinkage or elongation or by reducing the fluorescent properties in the case of warning clothing, standards require a cleaning test. Some standards also require strength testing, both prior to and following exposure of the sample to the maximum number of cleaning cycles as indicated by the manufacturer. The lowest performance level determined by such testing is indicated in the user information; the user is thus assured of the highest possible level of protection even following the potentially negative effect of cleaning. Such requirements should be included in all standards dealing with the cleaning of PPE.
The report provides a good overall picture of the standards situation at the time of the study. The detailed listing of individual standards and of the time-dependent performance characteristics addressed by them constitutes a practical aid during revision of the standards.
In the view of KAN, a potential deterioration in the protective action is largely considered in standards governing personal protective equipment. In some areas, however, recommendations are made for improvements, partly in the light of new findings.
The need for action on the part of standards developers
DIN is requested to forward the report to the German standards committees responsible for PPE, and via these committees also to the corresponding European standards committees, in order for the results to be available when standards are revised.
Recommendations to all PPE standards committees
Independent of the detailed proposals for improvements made in the report regarding the individual standards and types of PPE, the following proposals are of essential importance.
Products should bear a batch or serial number or other mark affixed by the manufacturer, as for example is already mandatory on PPE against falls from a height and on equipment for eye and face protection, in order to facilitate traceability and to enable the user or competent person to obtain information on the product from the manufacturer, such as the date of manufacture.
Many PPE standards require the user information to contain information on issues such as storage, use, cleaning, maintenance and servicing. Comprehensive requirements can particularly be found in revised standards and more recently issued standards. The extent to which older standards also require all necessary information to be included in the user information, and whether more far-reaching requirements could be included, should be reviewed. The scope should also be examined for the standards to ensure that manufacturers provide more detailed information on matters such as storage conditions.
Where the suitability for use of PPE and its protective action are strongly dependent upon stresses upon it and upon its care, provisions are recommended concerning more far-reaching manufacturer's information, extending above and beyond visual inspection, by which the user can determine whether the protective action is still adequately assured following use or storage. Standards governing PPE against cuts and stabs for example contain helpful recommendations regarding testing of the equipment for wear and deterioration in quality.
KAN recommends that standardized user instructions (model user instructions) be drawn up. The content of the user information should be structured uniformly for all types of PPE, not just that of respiratory protective devices, as proposed in the study. The necessary information, for example on proper and improper use, the limits of use, cleaning and care measures or warning information, could thus be found more easily by users, both where products from different manufacturers are used, and during the combined use of multiple types of PPE.
It is recommended that in the course of standardization work, consideration be given to dividing further types of PPE into performance levels/protective classes. Introduction of a classification would enable greater performance requirements to be set out for each successively higher level. This in turn would enable users to increase the level of protection by selecting a PPE product from a higher class, and to select suitable PPE for the task concerned. A further effect would be a reduction in the possible deterioration in the protective action in the course of use.
To summarize, the study recommends that at their revision, standards be reviewed regarding whether they give adequate consideration to the following requirements, where applicable to the type of PPE concerned:
- Resistance to weathering and temperature; flammability of the material
- Resistance of the material to mechanical stresses, corrosion, UV radiation, chemical substances
- Resistance of electrical functional or warning devices to electromagnetic interference
- Resistance of the material to cleaning/disinfecting agents and processes
- No emission of hazardous substances from the material of the PPE during use (innocuousness of PPE )
Requirements concerning the user instructions/manufacturer's information:
- Limits for use
- Checks prior to and following use
- Service life/use-by date, maintenance and replacement intervals
- Instructions for proper handling of the product
Special recommendations for particular areas
For the area of filtering respiratory protection, it is recommended that the relevant standards committee introduce provisions requiring either the inclusion in the user information of data permitting an approximate estimation of the service life, and/or a technical display of the use or of the residual service life (e.g. of gas filters).
The standards governing equipment for head protection should be reviewed with regard to the scope for introducing more far-reaching requirements for the user information, the purpose being for information on visual inspection and on the anticipated service life to be stated in addition to that on storage, use, cleaning, maintenance, servicing and disinfection. An example which may be cited here is that of prEN 443:2004 governing protective helmets for firefighters: in the revision of this standard, the scope of testing of the serviceability is to be extended, and for more far-reaching requirements for the user information introduced.
The instructions in the German BG Rule 192 (governing the use of equipment for eye and face protection) concerning the intervals for the replacement of lenses should be reviewed regarding their suitability for adoption into the European standard in the form of requirements for the user information.
In the area of PPE against drowning, the standards for buoyancy compensators, EN 1809:1997 and EN 12628:1999, should be adapted to the more stringent requirements of the prEN ISO 12402-1 to -10 series of standards, in order to take account of technical further development and of the particular hazards presented by the site of use.
Need for action by all KAN stakeholders
All KAN stakeholders are advised to lobby for "post-normative" studies to be conducted. Such studies serve to determine the effectiveness and suitability of the provisions and test methods contained in standards; they could also be used to reduce the discrepancies between test results and practical conditions to a possible minimum, in order for test methods to be developed (further) which, on the one hand, assure the necessary reproducibility and repeatability at acceptable expense, and on the other are able to measure the performance of PPE under real-case conditions.
Expert knowledge of the conditions under which PPE is used and also of accident patterns and causes of accidents should be incorporated to a greater degree into standardization activity. The result would be, on the one hand, that the needs of users would be addressed more effectively, and on the other, that requirements would be defined and information provided which could contribute to the avoidance of accidents resulting for example from improper use.
It is recommended that new technical developments be studied with regard to their potential for application in the area of PPE, in order to combat the deterioration in the protective action caused by ageing or use. RFID systems could for example be used for maintenance and repair, and also for recognition of whether protective equipment and tools are being used at the relevant workplace and whether they are maintained in accordance with the workplace regulations. A possible application of nanotechnology is conceivable in the impregnation of textiles (e.g. protective clothing), for example for modification of the water- and oil-repelling properties in order to improve the run-off of liquids.