Hands as standard issue
Digital connectivity (Internet-of- Things communication between processes and systems) making it possible for IT-enabled components to ‘talk’ to each other is a hallmark of early 21st century technology. However, the original digits, fingers, have been doing this for a long time.
Dextrous, flexible and endlessly ‘reprogrammable’, hands are responsible for many of our unique human productive and creative capabilities. At the same time, however, they are extremely vulnerable.
Our standard issue eight fingers, two highly efficient opposable thumbs, complex joints and sophisticated supporting tissue have underpinned our evolutionary success. But, we have been prone to injury and infection since, as early huntergatherers, we learned to play with fire. Since then, the rapid development of artificial industrial environments has multiplied our risks many times over.
“the introduction of the new BS EN 388:2016 test standards for mechanical damage will be a legal requirement by 2021”
Fortunately, progress has produced answers as well as problems. During the Industrial Revolution, hands were their owner’s responsibility when working with fast-moving metal and machinery. We might shudder at the thought of such unenlightened views today. However, maximum protection calls for continuous technical improvements. These are now embodied in new standards for a series of mechanical 28 performance test procedures that are about to supersede the current BS EN 388:2003.
BS EN 388:2016 aims
BS EN 388:2016: ‘Protective gloves against mechanical risks’ has been designed to make it as easy as possible for everyone in the workplace to identify and select the most appropriate protective gloves for the job ‘in-hand’ at any particular moment of the busy working day.
I say that, while being fully aware of the temptation and dangers created when work conditions require a different set of gloves to be used for, perhaps only a few dangerous minutes, when it is so much easier to take a chance with the pair that you are already wearing. Sorry, but compromise has no role in professional hand protection!
It is difficult to act retrospectively after a serious injury. We can issue better gloves, but we cannot provide new fingers, skin, bones and sinews as easily. Not yet, anyway.
This makes it crucial for everyone to be well-informed about personal hand protection, the technical advances that are improving the protection of their once-in-a-lifetime issue of free hands and the new identification protocols for sound glove selection, whatever the circumstances.
BS EN 388:2016 is ushering in an easy-to-understand simple visual information format known as pictograms that must be displayed clearly and permanently on all future gloves.
The first pictogram number will be a measure of the glove’s resistance to abrasion. The second will rank its circular blade cut resistance. Tear resistance is shown by a third numeral and puncture resistance by a fourth. The fifth indicator will be a letter, rather than a number, and refers to the straight blade cut test. When neither circular nor straight blade tests have been made, an ‘X’ will be shown. The final designation will be a ‘P’ mark when gloves meet detailed impact resistance requirements.
If test results are below Level 1 for any of the main test categories, the common convention is to add ‘O’. Should none of the tests meet a Level 1 or Level A rating, there will be no point in applying the pictogram system to that particular product.
Getting up to date
To account for modern technical and material changes in glove construction and performance, the ambitious BS EN 388:2016 standard will cover general-purpose protective gloves that form the largest market share of all personal protective equipment.
Importantly, the detailed standard has been drawn up to work in conjunction with BS EN 420:2003+A1:2009: ‘Protective gloves. General requirements and test methods’. This ensures that gloves themselves are not designed or manufactured in ways that could harm the wearer or cause any avoidable discomfort. To complete the protection, the BS EN 420 standard is itself being revised before being translated into BS EN ISO 21420 by the close of 2019.
BS EN 388:2016 lays out clearly the performance requirements, test methods, easy-to-read marker symbols and additional information that must soon be supplied with gloves that protect against the mechanical risks of circular and straight blade cuts, tears, punctures and, where relevant, impacts.
Each potential damage aspect is tested through separate and specific procedures that give direct performance levels. The higher the number or letter used, the higher the level of protection. To see how this works, it is helpful to understand how each test is carried out.
BS EN 388:2016 brings with it a major technical change in the selection of abrasive paper used with an abrasion machine. Material samples taken from glove palms are attached to a standard size and weight rubbing head that moves elliptically over a table covered not with a 100- grit abrasion material as specified by the 2003 standard, but a 180-grit paper. Grit is the number of abrasive grain particles per inch: the lower the grit, the larger the grain and the coarser the paper.
Four specimens are tested; the lowest result being taken as final. When glove construction involves multiple unbonded layers, each is tested individually. Here, the performance level is based on the total sum of the different cycles. The final results are expressed as four performance levels.
Level 1 represents the equivalent of a hole being created during 100 and 499 abrasive cycles; levels 2 and 3 respectively represent 500–1,999 and 2,000–7,999 cycles. Level 4 is the highest category for 8,000 cycles upwards.
For cut resistance, changes have been introduced to compensate for blade blunting during testing. The 2003 standard version included a circular blade cutting process called the coupe test. It also contained references to a straight blade cut test applicable for materials with a higher cut resistance.
In the coupe test, a rotating blade oscillates back and forwards over a flat material sample; for multilayer materials, the layers are tested under conditions similar to those expected for a working glove. An electrical contact indicates when the blade actually cuts through the test piece and completes a circuit with the undersurface.
The number of blade strokes is recorded. Because the sharpness of the blade is a potential variable, future testing will use a standard canvas reference sample as a control. Comparisons will be made before and after testing. Putting the two sets of results together enables a blade cut index value to be calculated that takes into account both the number of cycles needed to cut through the test material and the standard canvas. BS EN 338:2016 also introduces blade control improvements.
To ensure a meaningful average for materials that are highly likely to carry manufacturing variations, specimens are taken from two separate gloves, both of which undergo the cut test five times. A new blade index is then calculated for each test piece. The final performance level errs on the side of caution and takes the lower mean blade cut index from the specimen pair.
For easy, quick reference, this is expressed in a five-level advanced cut resistance grading. Level 1 indicates an index equal to or greater than 1.2, rising to a maximum of 2.5. The Level 2 index range is 2.5–5.0. After this, Level 3 is 5.0–10.0, with Level 4 being 10.0–20.0. Finally, Level 5 is greater than 20.0.
However, the circular blade cut test applied to materials based on composite fibres, including advanced technology aramids such as Kevlar and other high-property components, has restrictions. A significant problem in testing materials developed deliberately for their high cut resistance is blade dulling. This means that test results are inconsistent, especially when the second control sample is tested. Products such as glass fibres and very abrasive surfaces are likely to include spot variations that can deliver unreliable results between subsequent cuts. One further difficulty is that the electrical shorting effects often give false early fabric cut-through readings when steel fibres are involved.
The 2003 version of the standard ISO 13997:1999: ‘Protective clothing – Mechanical properties – Determination of resistance to cutting by sharp objects’, provides an alternative straight blade cut method. BS EN 388:2016 now incorporates this fully. The trigger point is that if the number of cycles necessary to cut the reference sample during any individual blade cut test triples or is greater than a factor of three the ISO 13997:1999 test method will become the default reference.
Straight blade cutting
In the straight blade cutting test, a blade under a precise vertical load or pressure is drawn once over the material sample. Crucially, each blade is only used once to avoid any possibility of blunting. The vertical force involved and the length of the cut in the material are both used to calculate the average force needed to achieve a 20mm-long cut; this force is then applied to the sample a further five times. If the resultant stroke length falls within the tolerances defined in the first part of the test, the full test is regarded as adequate and complete.
This time, the results are shown in Levels A through to F plotted against the force involved and measured in newtons (N). Level A requires a force ranging from 2N to no greater than 5N to produce a 20mm cut. Level B is 5–10N, Level C is 10–15N, Level is D 15–22N, Level E is 22–30N and, finally, Level F is greater than 30N.
In the case of both circular and straight blade testing, a warning needs to be added explaining that, although circular blade cut test results are only indicative, the straight blade resistance test is the reference performance result.
The tear resistance test method remains largely unchanged between the 2003 and 2016 iterations of the standard. It still involves taking samples from the palms of four different gloves: two longitudinally and two at right angles, laterally. These samples are held in a standard tensile strength testing machine with jaws moving apart at a constant speed of 100 mm/min. The forces needed to cause tear damage are then recorded. When multiple unbonded layers are involved, this test is applied individually to each layer; the lowest result of the most tear-resistant material is taken as the glove’s effective tear resistance. As with the other tests, a four-level ranking is used. Level 1 describes a material that can withstand a maximum force of 10–25N; Level 4 designates a tear strength greater than 75N.
When tear performance to Level 1 or above is provided, it is important to warn that the glove in question must not be used where there is any risk of entanglement with the moving parts of machinery.
As with tear resistance, no significant technical advances have been introduced in measuring the puncture resistance of protective glove materials. Again, four glove palm samples are prepared for test; with unbonded materials, the layers are mounted and tested together, as in actual use. A standard rounded stylus is pushed 50mm into the sample at a constant speed of 100mm/min. The maximum resistive force before puncturing occurs is then recorded.
Of the four test results, the lowest is taken. BS EN 388 defines Level 1 as the ability to withstand a puncturing force of 20–40N. Level 4, again the upper band, has the ability to resist a minimum force of 150N. Gloves made with composite or specialist materials may need a more demanding test, for example, materials designed to provide hand protection when hypodermic needles pose a threat. Here, needles rather than broad styluses are used for testing.
An impact resistance test specified by Clause 6.9 of BS EN 13594:2015 – ‘Protective gloves for motorcycle riders. Requirements and test methods’, is included as a BS EN 388:2016 option. It can apply when gloves are designed and manufactured to offer specific impact resistance in the palm, back of hand and/or knuckle areas.
When this test is used, the full glove is cut open and laid out flat so that individual impact tests can be made on each relevant area. The test applies an impact energy of 5J. Again, four separate test sequences are carried out on each vulnerable area. Samples from different gloves are used to produce reliable results. To be acceptable, gloves must meet Level 1 of BS EN 13594:2015 such that the average force transmitted should be equal to or less than 7.0kN. No individual result must pass on a force equal to or greater than 9.0kN.
When impact resistance is provided in the glove design, it is important to state clearly in the user instructions which parts are affected and emphasise that impact resistance does not apply to the fingers.
I know from my own experience that ensuring good practice and compliance within a large workforce operating over many different sites can be a logistical nightmare. It can be hard to account for human nature where risks are involved. That is why understanding what drives individual behaviour is important when it comes to sensible and responsible health and safety.
The introduction of BS EN 388: 2016 is a major step forward. Our challenge is to make sure that everyone understands what the new pictogram system means, the dangers involved in ignoring it and the inadvisability of taking shortcuts. Hands really are irreplaceable.
I believe passionately that employees should leave work in the same state of injury-free health and wellbeing as when they arrived. Achieving that really is a hands-on task!