half-cocked PPE

[Andy Smith]

Going backwards.

 

I have long hoped that some new PPE would be developed that increased safety for those working in HMA. Sadly, the new stuff I see on offer today is actually a 25 year step backwards. And the 2023 revision of IMAS 10.30 on PPE is also a significant reduction in the minimum requirement, which may have been ‘accidental’ but...  *Sigh* Now I have to arise from my slumbers and blow the dust off the old clickboard.

 

https://zebraprotection.com

 

The Zebra “Long Fragmentation visor” shown on that link looks like a crude copy of the original visors I made 25 years ago. These are the ones that were refined and have since been made by Security Devices for ROFI, Forceware and others – and which are used in almost every country.

 

The Zebra version is a crude copy because it has not been refined for weight and comfort – and has had no relevant tests. The stand-off from the wearer’s head at the sides is not flexible – so it is bound to be uncomfortable on most heads. The claim that it provides “ballistic” protection should alert any HMA purchaser to the fact that it has not been designed for use in HMA and does not comply with the latest IMAS 10.30.

 

The vendor claims that it “protects the face of the wearer from ballistic fragments”. As most of you know, “ballistics” is concerned with the launching, flight behaviour, and impact effects of projectiles, so objects that are ejected from some kind of guidance system (the barrel of a gun, for example). Having been guided gives these objects “direction” which increases the kinetic energy released during sudden impact.

 

The “spec sheet” for Zebra’s long visor gives no detail other than a claimed ballistic fragmentation resistance in their “in-house” tests of V50 300 m/s. If the material used is 5mm untreated polycarbonate (which used to be required in earlier IMAS) this claim is at best disingenuous but it may be a lie. They do not claim to have tested to NATO STANAG 2920 to find their V50, so it could be that it achieved this result in their own, less rigorous, Durban V50 tests. The best that 5mm untreated polycarbonate can do in a genuine and independent STANAG 2920 test is between 250 and 280 m/s (the nature of the material and permitted variations in fragment design explains the range). If they did not test to NATO STANAG 2920, you cannot compare the performance of their visor against others (but thanks be to the wisdom of the GiHAD you no longer have to).

 

In HMA, whether the visor can stop an air-gun pellet is not very relevant. The fragments associated with an AP blast mine have not been “guided” so are not ballistic. To comply with the IMAS, the test of a blast visor should involve multiple near-simultaneous strikes of randomly shaped and sized bits of mine casing, soil and stones (some of which are very hot) tumbling through the air at high speed. This should occur fractionally before the heavy impact of the blast wave associated with the detonation of 240g of TNT at 60cm. Designing a replicable lab-test with these features is challenging and the best compromise I have come up with is too expensive. Currently, the only way to test this is with TNT inside real mines. I have done a lot of these tests – and always had people with me to add “independence” to the results. More important, the visors made to my spec have done their job in a large number of real blast events. Empirical evidence will always trump compromised testing and the best guesses of mountain “experts”.

 

To comply with the new IMAS 10.30, anyone thinking of buying the Zebra visors should ask for evidence of well designed and independent blast testing – and should note that independent NATO STANAG 2920 test results would allow them to make a comparison with other products. Also, check whether the Zebra material is UNTREATED polycarbonate (because treated polycarbonate can increase the risk of shattering dramatically). If the Zebra material is thicker than 5mm, that is OK but the user should be aware that this increases the weight significantly and that this increases wearer discomfort. I recommend that they also try wearing one – and try it on a random half dozen heads. With that head-frame, I expect that it would be rather unstable and too uncomfortable to wear for long, but I might be wrong about that, of course.

 

Zebra should conduct some well designed blast tests using real mines (with independent observers) before they even think of selling to HMA customers...but will they?

 

Well, HMA purchasers should insist if they want to comply with IMAS 10.30. And the dear ol’ GiHAD should work out the details of a variables-controlled blast test that is easily replicable anywhere in the world so that the relative performance of products can be realistically assessed. Good luck with that! Meantime, thanks for leaving it to the “procurement” people to design and organise comparative blast tests before purchasing something that is cheap and which the vendor says is really good. I hope most of them will be wise enough to stick with what is known. 

 

*Sigh*

 

Back to the cowboy days.

 

Funny old roundabout world.

 

Regards,

Andy

[Andy Smith]

I have received a couple of private replies to my posting and it seems that I expressed myself badly – yet again! Sorry about that. Yes, being ballistic does not “increase”  the kinetic energy released during sudden impact, it concentrates or focuses it.

 

I should have stressed that the IMAS on PPE have been revised without reference to those who agreed the old version. The way it stands today, I can place my $1 sunglasses on the ground close to a PMN detonation, then recover my intact sunglasses and say they have been blast tested and they meet IMAS 10.30 – so issue them to my deminers. Without a defined blast test that is replicable by purchasers around the world, eye protection suddenly has no defined benchmark at all. Of course the previous fragmentation benchmark was not perfect - but it was something that had worked for two decades.

 

I have heard the famous Ratty person argue that mentioning a specific material (untreated polycarbonate) – and a thickness (5mm) was unnecessary. But the old IMAS did NOT require all eye protection to be made using 5mm untreated polycarbonate. It provided a benchmark by requiring any material used to at least match the performance of 5mm untreated polycarbonate in a 240g TNT blast and in a respected fragmentation test (NATO STANAG 2920). Treated polycarbonate has a surface hardened to become scratch-resistant, which is nice, but it cannot flex when hit by a blast so it shatters like perspex. This is why the benchmark was “untreated polycarbonate”. There were good reasons for all of the detail.

 

There have always been some bright people on the IMAS Review Board and I hope that some of them are listening because loss of eyes is already a very common disabling injury in demining. The old IMAS 10.30 prevented the use of cheap and ineffective eye protection. The new IMAS 10.30 allows the Pouched Rat and his cowboy friends to go back to using cheap industrial safety spectacles designed to stop the sparks from a workshop grindwheel.

 

Please will the IMAS Review Board revert to the old wording? If not, the sunglasses and shattering perspex visors that were widely used before there was a standard will be back with blindingly obvious consequences.

 

Does that matter? Well yes, it does a bit to the deminer. *Sigh*

 

Funny old world.

 

Andy

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