STANDARDS FOR PROTECTIVE HEAD GEAR
Analysis of the reports of previous accidents leads to the following conclusions:
Presently used hard hats (as distinct from a helmet), even though only moderately efficient, are saving lives and reducing injuries.
More lives could be saved by the increased use of better helmets.
A helmet is as important for protection of a falling climber as for protection from rock fall.
Retention of the helmet on the head is presently as big a problem as is the potential degree of impact protection.
Such observations led to the publication of the standards for industrial hard hats two years ago in this Safety Report. These were recognized as being inappropriate for climbers and led to a meeting in June 1965 at Berkeley, California. This meeting was sponsored by the American Alpine Club and Sierra Club. At this meeting were: John Armitage, Ed Leeper, Dr. Dick Long, Dr. Gil Roberts, Allen Steck, and Carl Weisner, who represented climbers, and Dr. George Snively from the Snell Foundation.
One of the questions asked at this meeting was: How effectively can any (reasonable) helmet protect the wearer’s head against impact? This question does not have a simple answer, and research is still underway to provide a more complete answer, but even now some rough estimates can be made. Realistic hypothetical examples could be posed as follows: From how high could a climber fall free, strike his head, and escape serious injury? How far could a baseball-sized (6 lb.) rock fall and hit a climber on the head without causing serious injury?
Type of Protection
Height of Climbers Fall
Height of Rock-fall
Caving hat (sling-suspension)
Climbing helmet (crushable liner)
Best car-racing helmet
It is important to realize that a helmet of the crushable liner type is partially destroyed during a severe impact, since both the liner and the shell are irreversibly damaged in the energy-absorbing process. The optimum protection would result essentially in destruction of the helmet.
Recommended Climbing Helmet Characteristics:
The helmet shall pass the current Snell Foundation requirements for ski- racing, auto-racing helmets. These requirements are quoted below with the permission of the Foundation.
General — The helmet shall consist of a hard, smooth shell lined with protective padding material or fitted with other means of energy absorption and shall be strongly attached to a strap designed to fasten under the wearer’s chin. The assembled helmet shall have a smooth external surface without reinforcing ridges or other rigid external projections except that a goggle clip may be used at the rear of the helmet if desired, and a ledge may be moulded at the front edge to support a visor. Such goggle clips shall not project more than three-sixteenths of an inch from the outer surface of the shell. Such ledge, if included, shall not project more than three-eighths of an inch from the outer surface of the shell, and shall not extend more than five inches from the midpoint in front toward either side.
Shell — The shell of the helmet shall be as nearly uniform in thickness and strength as is possible using normal manufacturing methods and shall not be specially reinforced at the test points. Ventilation holes, if used, shall not exceed one-half inch in diameter. Ventilation slots, if used, shall be placed over the ear area only, and must terminate in a rounded opening without any squaring of edges. Such slots shall not exceed one-quarter inch in width.
Helmet Height — The vertical dimension from the lower edge of the headband or other head fitting to the outside of the crown of the shell, at the midpoint of the helmet in a longitudinal axis shall not be less than five inches.
Extent and Form of Protective Material — The helmet shall be so constructed that any protective padding materials used shall cover the entire inner surface of the shell to a minimum lower trim line determined in the following fashion. At the midpoint in the front of the shell, the protective material shall extend to within five-eighths inch of the shell edge. Using this as a reference point, with the helmet in a normal upright position, the remainder of the protective material must extend to a plane running perpendicular to the vertical axis of the helmet and through the front reference point. The lower limit of protective padding material delineated above is to be considered an absolute minimum; any additional extension below this plane is to be considered highly desirable. Specifically, if shell extensions are used below the lower edge of the head fitting, they should be lined with protective padding material similar to that used in the upper part of the shell, and of comparable thickness, except that cut-out areas may be used to clear the ears.
Over the entire area covered by such protective lining substance, the material used must be of uniform construction and of thickness at least equal to its thickness at the rear of the helmet. No gaps in the protective padding materials shall be of greater width that one-quarter inch except corresponding to ventilation holes, which may be used up to one-half inch diameter. No part of this protective padding material shall be readily detachable.
Headband or Other Head Fitting — The headband or other head fitting shall not project below the lower edge of the shell at any point and shall be suspended or well-cushioned from the shell itself. Attention is drawn to the necessity of protecting certain materials which may be
used for this purpose against the effect of oil or grease from the wearer’s hair.
Harness — The head fitting shall consist of a sweat resistant material. The manufacturers shall ensure that the materials used in the harness are not of a kind to cause skin diseases. In the case of a material not in general use for this purpose, advice as to its suitability should be sought from a competent medical authority.
Finish — All edges of the shell shall be smooth and rounded, and there shall be no metallic parts or other rigid projections on the inside of the shell which could injure the wearer’s head in the event of a crash.
LABELING AND MARKING
There shall be securely attached to each helmet offered for sale a label bearing an inscription to the following effect:
For maximum protection this helmet must be of good fit and the chin strap must be securely fastened.
This helmet is so constructed that the energy of a severe blow is absorbed through the partial destruction of this shell and/or lining, although damage may not be visible to the naked eye. If it suffers such an impact, it should be either returned to the manufacturer for competent inspection or discarded and replaced by a new one. Helmets which comply with the requirements of this standard shall be marked as follows:
With the name, trademark, or other means of identification of the manufacturer.
With the month and year of manufacture.
With the certification mark of the Snell Memorial Foundation, which may be used by the manufacturer only under license from the Snell Memorial Foundation. Particulars of the conditions under which licenses are granted may be obtained from the Foundation.
In addition, the manufacturer’s name or trademark and the month and year of manufacture must be indelibly marked in an agreed code on the inside of the helmet in a position where this marking is protected from obliteration.
All helmets certified by the Snell Memorial Foundation must pass the following tests of shock absorption, harness and strap strength, and resistance to penetration. In addition to the initial testing prior to certification, random samples will be obtained by the Foundation from the open market, such samples to be replaced to the vendor by the manufacturer and these will be tested by the Foundation in similar fashion. Subsequent to certification, such random sample testing as is deemed necessary may be done by the Foundation or by an independent laboratory acceptable to the Foundation.
Shock Absorption Test —A test shall be instituted to establish a performance level in attenuating acceleration as a measure of the shock absorption property of the complete helmet. The helmet, mounted on an instrumented, 12 pound K-1A magnesium alloy head form, shall be subjected to impacts on front, rear and side, with a mass whose surface configuration shall be of spherical nature having a radius of 1.9 inch. The impacting energy shall be 120 foot pounds.
At this energy level “bottoming” shall not occur, nor shall the imparting acceleration exceed 400 G’s. In this test the head form shall be suspended in such a manner as to approximate a free mass.
The helmet must withstand a minimum of two such blows at each test site without failing the above conditions. The helmets shall be conditioned before testing as follows:
One helmet shall be conditioned in a thermostatically controlled oven maintained at a temperature of 125° plus or minus 5°F, for not less than four nor more than six hours, and subjected to impact testing within two minutes after removal. The humidity of the oven will be controlled at 50%.
A second helmet shall be refrigerated at a temperature of 0°F plus or minus 5°F, for not less than four nor more than six hours, and subjected to impact testing within two minutes after removal.
A third helmet shall be placed under a water spray at room temperature, with the flow rate of 15 gallons per hour over the outer surface of the helmet for a period of not less than four nor greater than six hours, and tested while wet.
Test for Attachment of Harness — The fastened chin strap shall be subjected to a test of tensile strength. The helmet shall be supported on a head form so that the points of attachment of the chin strap shall be subject to the same test as the strap itself. The strap and its attachments shall support a weight of 300 pounds without parting and without greater than one inch increase in the vertical distance of the chin strap from the helmet crown.
Test for Resistance to Penetration — After the preceding tests, sufficient exposure of the inner shell surface shall be made so as to allow unpadded shell to rest upon a rigid head form. A striker weighing four pounds and having a conical point with an included angle of 60 degrees, and a maximum tip radius of 0.020 inch, is dropped a clear distance of three feet so as to strike the crown of the helmet in the vertical axis of the head form.
The head form shall contain a cylindrical cavity 1.75 inches in diameter whose vertical axis shall be centered with that of the striking point. This cavity shall contain a means of recording the instantaneous vertical deflection of the inner surface of the shell within three-eighths inch of the axis.
When tested in the above fashion, the maximum vertical deflection shall not exceed three-eighths inch.
In addition, the helmet should meet the following requirements:
The helmet shall not restrict hearing.
The helmet shall have a neck-covering retention band of a material not restricting ventilation.
(c) The helmet shall be supplied, sized to 1/8 sizes, and shall not incorporate any interior suspension for the purpose of sizing. Sling suspension may be used only as a major part of the energy absorption design (this is presently not feasible, but future developments should not be ruled out).
4. Desirable Optional Features
Ventilation holes or slots, if effective and not resulting in an unreasonable compromise with the other prime requirements.
Minimum weight; 1 lb. is a desirable maximum.
Bright color, either white or international (fluorescent) orange.
Quick release chin fastening, adjustable, non-creeping.
Minimum use of leather and other organic materials.
Quotation by the manufacturer of the actual minimum level of performance attained during Snell impact tests.