BS EN 397-2012 pdf download.Industrial safety helmets.
Three sizes or headform are specified in this European Standard, size designations 525, 555 and 585 (equivalent to codes D. G and K, respectively, EN 960:1994).
Other than as specified in 6.5, helmets shall be tested on the headform of appropriate size (from size designations 525. 555 and 585), as selected by adjusting the headband/nape strap to the middle size of its adjustment range.
6.5 Measurement of clearance, distances and wearing height
Vertical and horizontal distances, internal vertical clearance and wearing height shall be measured with the helmet mounted in the wearing position successively on both the largest and smallest size of headlorm (from size designations 525, 555 and 585) appropriate to its adjustment range.
The helmet shall be maintained in position on each headform by the application of a force of 50 N acting along the vertical axis.
For the measurement of wearing height and horizontal distance, the headband shall be adjusted In the vertical plane to its highest position within the shell.
6.6 Shock absorption
6.6.1 Principle
Shock absorption is measured by the direct measurement of the maximum force transmitted to a
rigidly mounted headlorm on which the helmet Is fitted.
6.6.2 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.
The headform shall be rigidly mounted in a vertical position on the base.
A striker, having a mass of 5,0 kg and a hemispherical striking face of 50 mm ± 1 mm radius.
shall be positioned above the headform so that its axis coincides with the vertical axis of the headform and so that it may 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 obtain for free fall
The impact force shall be measured by a non-inertial force transducer firmly attached to the base. It shall be 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 damaqe.
6.6.3 Test procedure
Each of the requisite sample helmets specified In 6.1 shall be adjusted to its greatest possible
weanng height and conditioned appropriately in aCcordance with 6.2.
Within 1 mm of its removal from conditioning:
a) the sample shall be mounted on the appropriate headforrn (see 6.4.2) in the manner in which it is
intended to be worn on the head, ensuring (minimal) dearance between the headband and the
headform;
b) the sinker shall be allowed to fall on to the centre of the crown of the helmet shell from a height of
1 000 mm ± 5 mm, measured from the point of impact on the helmet to the underside of the
striker.
NOTE This corresponds to an impact energy of nominally 49 J.
A recording shall be made allowing the determination of the maximum force transmitted.
6.7 Resistance to penetration
6.7.1 PrInciple
A test striker is allowed to fall on to the helmet which Is filled to a rigidly mounted headlomi. Note is taken of whether or not contact is made between the striker and the headform or whether the contactable surface of the headform Is visibly damaged.
6.7.2 Apparatus
The base of the apparatus shall be monolithic and sufficiently large to offer full resistance to the effect of the blow.
The headforrn shall be rigidly mounted in a vertical position on the base. The contactable surface of the headform shall be of a metal that will readily permit detection should contact by the striker occur. and that can be restored after contact, if necessary.BS EN 397-2012 pdf download.