| Note to users: This electronic document is not subject to copyright. You may copy it, but you are requested not to disseminate altered copies. |
ACKNOWLEDGMENTS
This standard was formulated by the Law Enforcement Standards Laboratory of the National Bureau of Standards under the direction of Ralph A. Gorden Jr., Manager, Protective Equipment Program, and Lawrence K. Eliason, Chief of LESL. The technical research was Performed by Nicholas J. Calvano of the NBS Center for Consumer Product Technology. The standard has been reviewed and approved by the Technology Assessment Program Advisory Council and adopted by the International Association of Chiefs of Police (IACP) as an IACP Standard.
For sale by the Superintendent of Documents, U.S. Government
Printing Office, Washington, DC 20402
This document. NIJ Standard-0106.01, Ballistic Helmets. is an equipment standard developed by the Law Enforcement Standards Laboratory of the National Bureau of Standards. It is produced as part of the Technology Assessment Program of the National Institute of Justice. A brief description of the program appears on the inside front cover.
This standard is a technical document that specifies performance and other requirements equipment must meet to conform to the needs of criminal justice agencies for high quality service. Purchasers can use the test methods described in this report to determine firsthand whether a particular piece of equipment meets the standards, or they may have the tests conducted on their behalf by a qualified testing laboratory. Procurement officials may also refer to this standard in their purchasing documents and require that equipment offered for purchase meet the requirements. with compliance guaranteed by the vendor or attested to by an independent laboratory.
Because this NIJ standard is designed as a procurement aid. it is necessarily highly technical. For those who seek general guidance about the capabilities of ballistic helmets, user guides also are published. The guides explain in non-technical language how to select equipment capable of the performance required by an agency.
NIJ standards are subjected to continuing review. Technical comments and recommended revisions are welcome. Please send suggestions to the Program Manager for Standards, National Institute of Justice, U.S. Department of Justice, Washington, DC 20531.
Before citing this or any other NIJ standard in a contract document, users should verify that the most recent edition of the standard is used. Write to: Chief, Law Enforcement Standards Laboratory, National Bureau of Standards. Washington, DC 20234.
Lester D. Shubin
Program Manager for
Standards
National Institute of Justice
CONTENTS
Foreword
This revision redefines the classification system, and
establishes threat levels and test rounds that are consistent with companion NIJ
standards for ballistic protective equipment and materials [l,4]*.
The ballistic threat posed by a bullet depends, among other things. on its composition, shape, caliber, mass, and impact velocity. Because of the wide variety of cartridges available in a given caliber. and because of the existence of hand loads, helmets that will defeat a standard test round may not defeat other loadings in the same caliber. For example, a helmet that prevents penetration by a 357 Magnum test round may or may not defeat a 357 Magnum round with higher velocity. Similarly, for identical striking velocities, non-deforming or armor piercing rounds pose a significantly greater penetration threat than an equivalent lead core round of the same caliber. The test ammunition specified in this standard represent common threats to the law enforcement community.
2.1 Type I (22 LR-38
Special)
This
helmet protects against the standard test rounds as defined in paragraph 5.1.1.
It also provides protection against lesser threats such as 12 gauge No. 4 lead
shot and most handgun rounds in calibers 25 and 32.
2.2 Type II-A (Lower Velocity 357 Magnum-9
mm)
This helmet
protects against the standard test rounds as defined in paragraph 5.1.2. It also
provides protection against lesser threats such as 12 gauge 00 buckshot, 45
Auto., 22 caliber Long Rifle High Velocity (rifle), High Velocity 38 Special and
some other factory loads in caliber 357 Magnum and 9 mm, as well as the threats
mentioned in paragraph 2.1.
2.3 Type II (Higher Velocity 357 Magnum-9
mm)
This helmet
protects against the standard test rounds as defined in paragraph 5.1.3. It also
provides protection against lesser threats such as 12 gauge 00 buckshot, 45
Auto., 22 caliber Long Rifle High Velocity (rifle), High Velocity 38 Special and
most other factory loads in caliber 357 Magnum and 9 mm, as well as the threats
mentioned in paragraph 2.1.
2.4 Special Type
A purchaser having a special
requirement for a level of protection other than one of the above standards
should specify the exact test rounds to be used, and indicate that this standard
shall govern in all other respects.
3.2 Basic Plane
The plane through the centers of the external
ear openings and the lower edges of the eye sockets. See figure 2.
3.3 Coronal Plane
The plane, perpendicular to the basic
and mid-sagittal planes, which passes through the centers of the external ear
openings. See figure 2.
3.4 Fair Hit
A hit that impacts the helmet at an angle of
incidence no greater than 5°, and is at least 5 cm (2 in) from a prior hit or
the edge of the helmet. A bullet that impacts too close to the edge or a prior
hit and/or is of too high a velocity, but does not penetrate, shall be
considered a fair hit for the determination of penetration.
3.5 Full Metal Jacketed Bullet
(FMJ)
A bullet made
of lead completely covered, except for the base, with copper alloy
(approximately 90 copper-10 zinc).
3.6 Jacketed Soft Point
(JSP)
A bullet made
of lead completely covered, except for the point, with copper alloy
(approximately 90 copper-10 zinc).
3.7 Lead Bullet
A bullet made of lead alloyed with hardening
agents.
3.8 Mid-sagittal Plane
The plane, perpendicular to the basic
and coronal planes, which symmetrically bisects the head. See figure
2.
3.9 Penetration
Perforation of a witness plate by any part of
the test specimen or test bullet, as determined by the passage of light when the
witness plate is held up to a 60-W light bulb.
3.10 Reference Plane
The plane 60±1 mm (2.36±0.04 in)
above and parallel to the basic plane. See figure 2.
3.11 Witness Plate
A thin sheet of aluminum whose
perforation serves as a means of determining penetration.
4.2 Test Sequence
The helmets shall be examined to
determine compliance with the requirements of paragraphs 4.3 through 4.6, and
shall then be tested for compliance with the requirements of paragraphs 4.7 and
4.8 in that sequence.
4.3 Projections
The helmets shall have no rigid projections
that protrude from the inside shell surface.
4.4 Openings
The helmets shall have no slits, holes, or
other openings.
4.5 Workmanship
The helmets shall be free from dents, blisters,
cracks, crazing, chipped or sharp corners and other evidences of inferior
workmanship.
4.6 Labeling
Each helmet shall be permanently and legibly
labeled so that the label can be easily read without removing padding or any
other permanent part, and shall include the following information:
4.8 Ballistic Impact
Attenuation
One
helmet shall be tested for ballistic impact attenuation in accordance with
paragraph 5.3. No measured peak acceleration shall exceed 400 gn ,
(400 times the acceleration due to gravity).
5.1 Test Equipment
It should be noted that hand-loaded
ammunition may be required to achieve some of the bullet velocities required in
the following paragraphs.
5.1.1 Type I Test Weapons and Ammunition
5.1.1.1 22
LR
The test weapon
may be a 22 caliber handgun or test barrel. The use of a handgun with a 15 to
16.5 cm (6 to 6.5 in) barrel is suggested. Test bullets shall be 22 Long Rifle
High Velocity lead, with nominal masses of 2.6 g (40 gr) and measured velocities
of 320±12 m (1050±40 ft) per second.
5.1.1.2 38 Special
The
test weapon may be a 38 Special handgun or test barrel. The use of a handgun
with a 15 to 16.5 cm (6 to 6.5 in) barrel is suggested. Test bullets shall be 38
Special round-nose lead, with nominal masses of 10.2 g (158 gr) and measured
velocities of 259±15 m (850±50 ft) per second.
| Test variables | Performance requirements | |||||
|---|---|---|---|---|---|---|
| Helmet type | Test ammunition | Nominal bullet mass | Suggested barrel length | Required bullet velocity | Required fair hits per helmet part | Permitted penetrations |
| I | 22 LRHV Lead | 2.6 g 50 gr |
15 to 16.5 cm 6 to 6.5 in |
320±12 m/s 1050±40 ft/s |
4 | 0 |
| 38 Special RN Lead |
10.2 g 158 gr |
15 to 16.5 cm 6 to 6.5 in |
259±15 m/s 850±50 ft/s |
|
| |
|
|
357 Magnum JSP |
10.2 g 158 gr |
10 to 12 cm 4 to 4.75 in |
381±15 m/s 1250±50 ft/s |
|
|
| 9 mm FMJ |
8.0 g 124 gr |
10 to 12 cm 4 to 4.75 in |
332±15 m/s 1090±50 ft/s |
|
| |
|
|
357 Magnum JSP |
10.2 g 158 gr |
15 to 16.5 cm 6 to 6.5 in |
425±15 m/s 1395±50 ft/s |
|
|
| 9 mm FMJ |
8.0 g 124 gr |
10 to 12 cm 4 to 4.75 in |
358±15 m/s 1175±50 ft/s |
|
| |
5.1.2.1 Lower Velocity 357 Magnum
The test
weapon may be a 357 Magnum handgun or test barrel. The use of a handgun with a
10 to 12 cm (4 to 4.75 in) barrel is suggested. Test bullets shall be 357 Magnum
jacketed soft point, with nominal masses of 10.2 g (158 gr) and measured
velocities of 381±15 m (1250±50 ft) per second.
5.1.2.2 Lower Velocity 9 mm
The test weapon may be a 9 mm handgun or test barrel. The use
of a handgun with 10 to 12 cm (4 to 4.75 in) barrel is suggested. Test
bullets shall be 9 mm full metal jacketed, with nominal masses of 8.0 g (124 gr)
and measured velocities of 332±15 m (1090±50 ft) per second.
5.1.3 Type II Test Weapons and Ammunition
5.1.3.1 Higher Velocity 357 Magnum
The test weapon may be a 357 Magnum handgun or
test barrel. The use of a handgun with a 15 to 16.5 cm (6 to 6.5 in)
barrel is suggested. Test bullets shall be 357 M g a num jacketed soft point,
with nominal masses of 10.2 g (158 gr) and measured velocities of 425±15 m
(1395±50 ft) per second.
5.1.3.2 Higher Velocity 9 mm
The-test weapon may be a 9 mm handgun or test
barrel. The use of a handgun with a 10 to 12 cm (4 to 4.75 in) barrel is
suggested. Test bullets shall be 9 mm full metal jacketed, with nominal masses
of 8.0 g (124 gr) and measured velocities of 358±15 m (1175±50 ft) per
second.
5.1.4 Chronograph
The chronograph shall have a precision of 1 µs and an
accuracy of 2 µs. Its triggering devices shall be of either the
photoelectric or conductive screen types.
5.1.5 Penetration Test Headforms
Each penetration test headform shall be size 7
l/4 and shall have the dimensions shown in figure 3. The sagittal
penetration type shall be so modified that it can rigidly hold a witness plate
in the coronal Plane as shown in figure 4. Conversely, the coronal penetration
type shall be able to hold a witness plate in the sagittal plane. as shown in
figure 4.
5.1.6 Impact Test Headform
The impact test headform shall be size 7 l/4.
shall have the dimensions given in figure 3, and shall exhibit no
resonance frequencies below 3000 Hz: it may be made of any suitable material.
such as magnesium alloy K-1A. A test headform found to be suitable can be
obtained from United States Testing Laboratories, Inc., 1415 Park Avenue,
Hoboken, NJ 07030.
The impact headform shall be rigidly mounted on a base (see fig. 5) which is free to move In the direction of motion of the test bullet. The total mass of the instrumented headform and base assembly shall be 5.0±0.5 kg (11 ± 1.1 lb) and the static force, parallel to the direction of motion, required to initiate motion of the assembly shall not exceed 9 N (2 lbf).
5.1.7 Witness Plate
The witness plates shall be 0.5 mm (0.020 in) thick. and
shall be made of type 2024-T3 or 2024-T4 aluminum alloy. 
5.1.8 Acceleration Measurement System
The
accelerometer should be able to withstand shocks up to 2000 gn . The
acceleration data channel, including all instrumentation which may alter the
frequency content of the test data and all recording and analysis procedures,
shall comply with SAE Recommended Practice J211b requirements for channel class
1000 [5].
5.2 Ballistic Penetration Test
Set up the test equipment as shown in figure 6.
Firmly clamp the appropriate test weapon, with the barrel horizontal. in
such a manner that the alignment of the weapon is not altered when it is
discharged. Use the test weapon and ammunition combination in accordance with
paragraphs 5.1.1.1 through 5.1.3.2 as appropriate for the threat level
classification of the helmet as rated by the manufacturer in accordance with
section 2.
Position a sheet of cardboard 5 m (16 ft) from the muzzle of the test weapon and fire a pre-test round through the cardboard to determine the line of flight and the point of impact of the bullet.
Place the triggering devices 2 and 3 m (6.6 and 9.8 ft), respectively, from the muzzle of the test weapon and arrange them so that they define planes perpendicular to the line of flight of the bullet. Measure the distance between them with an accuracy of 1 mm (0.04 in).
Insert a witness plate in the sagittal penetration test headform. place the helmet under test on the headform and secure it by its chin strap or by other means which will not interfere with the test. Place the helmeted headform in back of the sheet of cardboard, with the desired point of impact touching the bullet hole made by the test round. and then remove the cardboard.
Fire one round at the front of the helmet, hitting it at a point no more than 9 cm (3.5 in) above the basic plane and no more than 5 cm (2 in) from the mid-sagittal plane. Record the time of flight of the bullet between the two triggering screens, as determined by the chronograph, and calculate the bullet velocity. Then fire a round at the back of the helmet, impacting it within the area diametrically opposite the front impact area. Examine the helmet and witness plate to determine whether penetration occurred when a bullet traveling at an acceptable speed made a fair hit within the required area.
If no penetration occurred, place the helmet on the coronal penetration test headform and shoot it once on each side. at a point no more than 5 cm (2 in) above the basic plane and no more than 7.5 cm (3.0 in) from the coronal plane.
If no penetration occurs, repeat the
above test on a second helmet, which has been preconditioned by immersion
for 2 to 4 h in water at 25±5°C (77±9°F).
5.3 Ballistic Impact Attenuation Test
Set up the test equipment as shown in figure 6
and locate the line of fire and point of impact of the bullet as described in
paragraph 5.2. Use the test weapon and ammunition combination in accordance with
paragraphs 5.1.1.1 through 5.1.3.2 as appropriate for the threat level
classification of the helmet as rated by the manufacturer in accordance with
section 2.
Mount the accelerometer at the center of mass of the impact test headform in such a manner that it can be easily repositioned for all impacts: a universal ball-and-socket mount has been found to be suitable. Position the helmet squarely on the headform and secure it by its chin strap or other means which will not interfere with the test. Position the instrumented test headform-base assembly in the line of fire so that the sensitive axis of the accelerometer and the line of fire are colinear within 5°.
Allow all electronic equipment to warm up for 30 min or until stability is achieved, whichever time is greater, prior to testing, and perform the tests at an ambient temperature of 20-28°C (68-82 °F) and a relative humidity of 30 to 70%. Shoot four test rounds at the helmet, one at each of the four sites as described in paragraph 5.2, and measure the velocity of each fair hit and the headform acceleration which it produces.
APPENDIX A-REFERENCES
1. NILECJ-STD-0101.01, "The Ballistic
Resistance of Body Armor," National Institute of Justice, U.S. Department
of Justice. Washington, DC 20531 (Dec. 1978). 2. NIJ Standard-0104.01, "Riot
Helmets," National Institute of Justice, U.S. Department of Justice, Washington,
DC 20531 (Aug. 1980).
3.
NILECJ-STD-0105.00, "Crash Helmets," National Institute of Justice, U.S.
Department of Justice, Washington, DC 20531 (June 1975).
4. NIJ Standard-0108.00, "Ballistic Resistant
Protective Materials." (In preparation).
5. SAE
Recommended Practice J211b, Society
of Automotive Engineers, Inc., Two Pennsylvania Plaza, New York, NY.
* United States Government Printing
Office:1982--361-233/6344
Return to
PoliceOne
This WWW version last revised 1999 February 25.