BS EN 812:2012 pdf download – Industrial bump caps
6.4.2 Selection of size Three sizes of headform from the range in EN 960:2006 are specified in this European Standard, size designations 525, 555 and 585 (equivalent to codes D, G and K, respectively, EN 960:1994). Bump caps with adjustable harnesses shall be tested on the most appropriate size headform (from size designations 525, 555 and 585) as selected by adjusting the harness to the middle size of the adjustment range. Bump caps with non-adjustable harnesses shall be tested on the most appropriate size of headform (from size designations 525, 555 and 585). 6.5 Impact protection
6.5.1 Principle Impact protection is measured by the direct measurement of the maximum force transmitted to a rigidly mounted headform on which the bump cap is fitted.
6.5.2 Apparatus The base of the apparatus shall be monolithic and sufficiently large to offer full resistance to the effect of the blow. It shall have a mass of at least 500 kg and shall be suitably installed to obviate the return compression wave. A striker, having a mass of 5,0 0 1 , 0 − + kg and a flat striking face of (100 ± 2) mm diameter, shall be positioned above the headform so that its axis coincides with the central vertical axis of the headform, and so that it can be dropped in either free or guided fall. If guided fall is employed, the velocity of the striker, measured at a distance not exceeding 60 mm prior to impact, shall be within 0,5 % of that which would be obtained for free fall.
The impact force shall be measured by a non-inertial force transducer firmly attached between the base and the headform and so positioned that its axis is co-axial with the path of the striker. The force transducer shall be able to withstand forces up to 40 kN, without damage. The headform(s) shall be rigidly mounted in two orientations, such that the vertical axis, which passes through the centres of the striker and the force transducer, also passes through a point in the headform (defined by the intersection of its central vertical axis with the AA’ plane), when the central vertical axis of the headform is inclined backwards at angles of 30° and 60° respectively. The measuring system, including the headform and its mounting, shall have a frequency response in accordance with channel frequency class (CFC) 600 of ISO 6487:2002.
6.5.3 Procedure Each of the requisite sample bump caps specified in 6.1 shall be adjusted to its greatest possible wearing height (if applicable) and conditioned appropriately in accordance with 6.2. Position the headform such that its central vertical axis is inclined backwards at an angle of 30°. Within 1 min of its removal from conditioning:
a) mount the sample on the headform, front upwards, in the manner in which it is intended to be worn on the head, ensuring (minimal) clearance between the headband, if fitted, and the headform;
b) allow the striker to fall on to the bump cap from a height of (250 ± 5) mm, measured from the point of impact on the bump cap to the underside of the striker.
NOTE This corresponds to an impact energy of nominally 12,5 J.
Make a recording allowing the determination of the maximum force transmitted.
c) Reverse the bump cap on the headform and repeat test b) on the back of the bump cap.