Helmets can only protect when retained on the head, therefore, a chin strap may be supplied to ensure retention in typical workplace conditions. EN 397 requires that either the helmet shell or the headband is fitted with a chinstrap or with the means of attaching one, i.e. anchorage points. Any chinstrap supplied must have a minimum width of 10 mm when un-tensioned and be attached either to the shell or to the headband.
The strength of the strap anchorage(s) should be sufficient to enable any attached chin strap to hold the helmet on the head but not so great that the strap would become a strangulation hazard. In the method for measuring chin strap anchorage strength specified in EN 397 the helmet is mounted onto a suitably sized headform and the chin strap passed around an artificial jaw. A tensile force is then applied to the artificial jaw at a rate of 20N/min until the artificial jaw is released, due to failure only of the anchorage(s). The standard requires that the force at which this occurs shall be no less than 150 N and no more than 250 N.
EN397:
Safety Helmets or Hard Hats are required to pass certain tests to ensure they are fit for purpose. Industrial helmets are designed to give protection against Impact, Penetration and offer Shock Absorption.
Impact / Shock Absorption
The test centres have a piece of kit that performs this test. The helmet is placed on a head shaped mould, which has load detectors on it, the 5KG rounded striker is dropped on to the hard hat from a height of 1 metre, the load cell will record the force transmitted through the safety helmet, for the helmet to pass, the force must not exceed 5kN. The test is done several times and includes high and low temperatures, as well as helmet samples that have been immersed in water and exposed to UV rays.
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Penetration
This is a similar test, but the domed weight is replaced with a pointed 3KG weight. If the point penetrates the helmet, it fails.
Chin Straps
For a Hard Hat to do its job, it has to stay on the head, usually the size adjuster will be adequate, some tasks will require a chin strap to keep the helmet in place. All helmets conforming to EN397 must have chin strap anchorage points. EN397 Industrial Safety helmets with a chin strap must release when force is applied (150-250N) this is to ensure the helmet doesn't strangle the wearer. Unlike Climbing helmets conforming to EN where the chinstrap is tested not to break or release.
Each Hard Hat must have the following information marked on it:
There are further tests which can be done to Industrial safety helmets which might be useful for other hazards in the workplace, these are the following and the helmet will be stamped with the relevant markings:
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