concealable body armor - lexipolthe need for wearing body armor arises, when a high threat...

Body ArmorConcealable

About this booklet 3Checklist for purchasing a body armor 3Terms used for security technology 4

Contents

Wearing comfort & acceptance 5 Ballistic performanceand characteristics 9Influencing the ballistic performance 14

Aramid fabrics 16HPPE-Shield 17Aramid-Shield 18PBO-Fabrics 18Hybridsystems 19System Comparison 20

Technical guidelines 20The ballistic test protocol 21How to read a ballistic test protocol 21

How to wear a body armor ? 22

About this booklet

Nowadays life threatening situations are not foreseeable. As a member of a business branche with a

high danger level, active risk handling stands in the foreground.This includes regular wearing of

body armor. Since problems with protective vests occur often during wearing you must take the

following questions into account before purchasing a vest:

§ Which protection must be offered by the vest, do I need extra stabbing protection inserts?

§ How do the ballistic materials differ from each other?

§ Is there a need for a tailor made vest or does a standard one also sufficide?

§ How are the outer shells designed which extras are available?

§ Where are the vests manufactured ?

§ Can I contact the manufacturer directly if problems occur?

§ Which services are offered to me ?

§ Who can alter the vest and which cost arise thereof?

Always keep in mind that you might wear the armor daily over long periods of time on your body.

Therefore unconditionally ask for the biological and medical tolerability of the used materials and

textiles.

Checklist for purchasing a body armor

Many changes occured during the last years in the filed of safety technology for body protection. On

one side new protective systems were developed and on the other hand the number of

manufacturers and whole salers increased. The invention of new trademarks and terms finally lead

to a totally confusing situation on the market for body protection systems. As buyer, better said user

of body armor you should nonetheless inform yourself into which protection system you give your

life and safety. With this booklet we would like to give you information so you can form an impression

for yourself which protective system fits you best.

As manufacturer of personal body armor systems we are well aware of the problem to provide

objective and unbiased information. But keep in mind that we can in general produce and deliver all

in this brochure described body armor and systems. According to our experience with the different

systems and our customers reactions some systems proved very advantegeous. Certainly we dont

want to keep this experiences away from you therefore this brochure was designed. If after reading

this manual you should have further questions, please feel free to contact us. We always have an

open ear for recommandations and new ideas since we can improve a good product only, if we

respond to the wishes and needs of our customers

Terms used for safety technology

What is Safety ?

The term of safety is defined in the industrial standard DIN 31004. Safety is closely related to the

term risk. Risk consists of the eventuallity of a damage and the extend of this damage . During the

state of safety the risk is smaller than the still justifiable risk. Absolute safety without any risk does

not exist wether in technology nor in nature.

What doe these “abstract” term mean for body armor?"

The need for wearing body armor arises, when a high threat probability with weapons is given.

This is for example always the case for officers and task forces of the police.

Protection is the risk decreasing through taking steps which either minimize the occurence

probability or extend of damage, ideally both. Since most of the times you can´t alter the probability

of the threat (for example forget about a certain police task) you lower the risk if you minimze the

results and thereby possible damages.

Based on the numerous threats of a large number of weapons it is not possible to always consider

the maximum damage. Out of this reason body armor is divided into several protection classes.

Before the commitment the kind of threat must be evaluated. Based on this the threat level is

determined and protective clothing is chosen. The following table shows a rough overview of the

german thread levels:

ThreadLevel

Comment Rounds Velocity v0

[m/s]Areal weight

2[g/dm ]Armor

L

1

2

3

4

Protection against soft point bullets fired with a handgun

Protection against soft point bullets fired with a submachine gun

Protection against soft point bullets fired with a rifle

Protection against armor piercing bullets fired with a rifle

Protection against commercial quality bullets fired with a submachine gun

9mm ParaVMR/WK

9mm ParaVMR/WK

.357 Magn.MsF

.308 Win.VMS/WK

.223 Rem.WK+P

.308 Win.VMS/HK

365 ± 5 45 Soft body armor

Soft body armor

Additional plates

Additional plates

Additional plates

75

300

450

550

410 ± 10

580 ± 10

830 ± 10

920 ± 10

820 ± 10

The following table explains some terms which repeatedly occur in consense with body armor.

Outer Shell Fabric clothing, into which protective systems (panels, shock absorbers,

stabbing protection) are inserted.

Panel Ballistic package, consisting of the ballistic inserts packed into the panel

clothing.

Panel Clothing The ballistic insert is packed into a panel clothing to protect it against

environmental influences.

Ballistic Ballistic protective materials consist of highly resistant materials. Only this

inserts offer a protection against attacks with bullets.

Shockabsorbers Shockabsorbers can lower the impact of hitting bullets. They are inserted in

addtiton to the panels into the assigned pockets of the outer shell, positioned

between panel and body.

Trauma pack A trauma pack serves as a shockabsorber and is inserted in front of the

panel.

The following chapter discusses factors which influence and determine wearing comfort and

acceptance of body armor.

Weight

Weight is most of the times over evaluated, when choosing a vest. The weight results out of the 2area weight (weight per dm ) of the ballistic material and size of the protected area. Therefore the

vests should not be compared to each other according to its actual weight but with the area weight

in mind (since a vest with a smaller protection area always weights less than a vest with a larger

protected area). The area weight can be found in the official ballistic test protocol. The weight can

be only recognized after long periods of wearing.

Flexibility

A construction feature of nature is to stiffen soft basic materials through domed structures.

Unfortunately this effect can also be recognized with body armor. Therefore a vest hold in the hand

appears tremendiously softer than when it is worn on the body. So softer constructions only offer

at the edge areas a higher comfort. This additional comfort is bought at the cost of a weaker edge

shelling result. A possible solution is the choice of a not so soft construction where the edge

contours are very sharply designed to the body.

Wearing Comfort and Acceptance

Determining the indivudal contour

The contour of the ballistic inserts is determined by the specific body data but also of the type of

duty. This results in the following criteria for determining the contour:

Length The correct length of the vest is the most important measurement for the

contour.It has to be chosen in such a manner, that working in all duty situations

without any restriction is guaranteed. Especially make sure while you are

sitting in a car no problems arise.

Arm Section While moving your arms, e.g. steering a car, a limitation is considered as

disturbance. That is the reason why the contour is here determined very

carefully and optimally adjusted to the body.

Bone structure Sometimes the vest is felt as “pressing” at the collarbone. In this case a

contour must be defined to delete this pressure.

Concealable The contour must be determined in away that the vest is not recognized by the

opponent, because otherwise the probability for a head shot increases many

times.

All Around The girth of the contour must be determined so that a lateral overlapping of

Protection at least 2-3 cm is guaranteed. While wearing the body armor, the layers

fan out at both sides for about 2-3 cm at the edge. With this knowledge that

every vest has protective weaknesses at the edge area a none overlapping

only touching vest has an unprotected area of about 10 cm on each side.

This is the reason why many countries stipulate all around protection body

armor.

Field of activity Long working hours in vehicles, on bikes or on horseback afford according to

a compressed posture a very exact determination of the length.

Women The following solutions are offered to women:

1. Molding to cups

§ low wearing comfort, since only a small number of cups is available.

§ The form is obvious and easily recognized by potentional opponents as

body armor

2.Special stitching in the ballistic material

§ thumb thick joint at the chest area can lead to unpleasant pressure

feelings.

3.Men´s vests

§ Problematic with big cups

4.Geometric solutions

§ For every body a sole contour is determined. With this crease points are

programmed which enable the manufacturer the production of a cup.

Phase 1 - Standard sizes

During the first years, body armor was produced in standard sizes S, M, L,

XL. The cuts were developed according to standard sizes. The textile

research facilities issue every year the actual european average sizes to

give the textile industrie guidelines. This system is very simple for handling

purposes and reduces production costs. Since only 5% of the vests fit

perfectly, the wearing comfort is rather low. These vests normally lie in the

trunk of a car, in the locker or in the cellar of the police station.

Phase 2 - Standard sizes with length steps

In the following years vests with length steps were offered, mostly by

american manufacturers. A division into 5 steps gave a significant higher

wearing comfort. With this measurement the “throat choking” problem while

sitting in a car was improved.

Phase 3 - Standard sizes with length steps and fine tuning

A further improvement resulted out of the invention of fine tuning

measurements. It enabled e.g. the invention of variations of arm sections

and throat area design which resulted in a higher acceptance of wearing

body armor over longer time periods.

Phase 4 - Describing the contour with mathematical curves

The only possibility to find the optimal vest for every user lies in the individual

description of the body contour. The contour of the body armor parts are

described with mathematical curves (Splines). With the help of a parameter

set, the so called ShapeCode, the individual form of the protective systems

is defined.

Fit

Fit is the most important factor for a high wearing comfort. The lightest vest is felt as uncomfortable

if it doesn´t fit. The historic development of the custom fit of body armor can be divided into 4

phases:

V1

V4

V5V6

V3

V2

V1V4

V5U

5 3 0 0 0 00 0 01

L V6reservedV3

V2

Perspiration

Body armor causes restricted air circulation in the area of the ballistic inserts. Therefore additional

measurements must be taken to confront the problem of “perspiration under the vest”.

Every day the skin evaporates about 1 litre of body fluids. This vital process is also called

perspiration and serves to regulate our body temperature. Through physical activity or increased

environmental temperatures the production of perspiration is increased. Problems occur if the

moisture cannot evaporate from the skin. At winter you start to freeze, at summer the body can not

be cooled efficiently.

Well-being and performance are reduced. Aggressiv

perspiration can attack the skin and body armor. To solve

this problem a peel into the high athletic department is

useful. Herein thermo-active textiles are used since a long

time. The princip of a so called Thermo-Activ-Shirt is to

transport the moisture away from the skin.

Good ThermoActiv-Shirts feature a multi layer construction, where the layer close to the skin

transports the moisture outside and resembles thereby a buffer. In the second layer the moisture is

stored. The buffer time is sufficient so that the moisture is transported away through the

construction of the outer shell.

The simpler single layered shirts only serve for the simple moisture transport and are therefore

only partially suited for the use under body armor.

Less suited are terry inserts, since with this system all parts from undershirt to vest are soaked wet

and the armor becomes more bulky. Additionally this wetting enhances the vests weight, colds

down and becomes very uncomfortable to wear.

With older outer shells it is still often seen that net like fabrics, so called meshfabrics, are being

used. These fabrics were constructed to transport moisture to the outside. This works very badly

since the outside material stores moisture mostly at the edges and dries very badly.

A better moisture transport results out of the usage of homogenious materials in- and outside,

containing low cotton portions. The transport material is mostly polyesther or polypropylen silk.

Skin

Single layer Multi layer

SkinTextile Textile

Through the outstretched position of the fibres the energy of hitting bullets will be directly absorbed

by the fibres and will not be deflected over the knots of fabrics.

Ballistic Performance and Characteristics

Concerning “ballistic performance” the ballistic basic materials are examined closer, the different

ammunition and shelling types explained and terms like trauma value and shock absorbers

discussed in detail.

Yarn

The ballistic performance is mostly determined by the attributes of the yarns which are used in the

protective construction. In the machines of the yarn producers the yarn is spinned out of many

individual fibres. The most important feature is the strength of the yarn. Industrial wise

momentarily three fibres are being produced for manufacturing ballistic armor. The best known

fibre is called Aramid and is being offered under the trademark of Twaron (Acordis, formerly Akzo)

and Kevlar (of DuPont). The most resistent fibre is HPPE (High Performance Polyethylen) and is

sold under the brands Dyneema (of DSM) and Spectra (of Honeywell, formerly Allied Signal). The

strongest fibre is a PBO fibre, available as Zylon (of Toyobo).

Ballistic Systems

The yarns alone obviously don´t give a ballistic package. A ballistic insert consists of a preset

number of layers of the ballistic protective material. In ballistics two textile structures are used,

fabrics and shields. In each layer one of the mentioned yarns is being used. Fabrics are

manufactured in weaving mills. Inside of the ballistic package they must be sewn together, that

means that the layers are fixed with cross stitches. In former times the fabric packages were

stitched over the whole area which resulted in the stiffening and a nearly impossibility of wearing

the vests. Modern fabric packages are only stitched partially. Shields are a unidirectional system.

The fibres are hereby not interwoven but laid paralle together to each other. Each layer consists of

two or more of this layings and turned 90 degrees to each other. This product is fixed by foils from

top and bottom.

Foil

Layer, 0°Layer, 90°

Layer, 0°Layer, 90°

Foil

Shield structure

Screen Electron Mikroskop (SEM)picture of Dyneema

The described yarns are offered in the following structures:

Ammunition

The effect of bullets on ballistic systems depends on several factors:

§ material of the bullet (hard and soft core)

§ form of the bullet (semi jacketed, action, ...)

§ speed and energy of the bullet (loading stength, barrel length,...)

§ stability of the bullet (spinning length,...)

The shield-structur was originally developed for aeronautic and space technoloy and transfered

into the area of ballistics by Honeywell (Allied Signal). The following table compares the attributes

of fabrics and shields:

Criterion Fabrics Shield

Ballistic edge test

Stabbing protection

Ballistic angle test

Trauma values

Flexibility

Appreciable protection, starting at 3cm from the edge

Most of the fibers are pushed aside, when the weapon penetrates.

Number of layers and the proper fiber finish are important for a solid stopping performance.

Softer fiber finish results in higher trauma values.

Flexibility depends on the fiber finish. In favour of wearing comfort a softer finish is used most of the time.

Appreciable protection, starting at 1,5cm from the edge

Compared to fabric, more fibers must be cut by the weapon and therefore improved stabbing obstruction.

Good protection due to a high coefficient of friction of the shield.

Improved distribution of energy based on the physical structure and therefore lower trauma values.

Increasing wearing comfort in time, subjectively rated stiffer than fabric.

Fabrics

Aramid

HPPE

PBO

Shield

Twaron (Acordis)Kevlar (Dupont)

GoldFlex (Honeywell)

Nearly exclusive for composition structures - hybrids

Dyneema (DSM)Spectra-Shield (Honeywell)

Zylon (Toyobo) Under development

§ distance weapon- ballistic armor (ballistic test at 10m, set-on shot,...)

§ angle of incidence (straight or angled testing)

§ hitting area (edge, center)

§ climatic conditions (temperature, moisture,...)

Some of this parameters are tested in the german protective class I. Despite that more often

ammunition appears which vary tremendiously in form, material and loading strength. For

protection in these cases the reserves of a protective system gain significance. Hard core

ammunition falls under a higher protective class and will not be stopped by concealed soft body

armor. For this type of ammunition insert plates according to the respective protection class are

necessary.

Ballistics

Upon entering of bullets into ballistic layers the following values can be measured:

stopping power penetrating shot , lodged bullet or deflection

trauma value depth and diameter of the indent

number of layers number of undamaged layers

Stopping power

If a bullet is stopped and can be seen in the last layer of the ballistic package this shot is counted as

a penetrating hit. If a bullet completely penetrates the ballistic armor the form of the bullet will be

changed. These “popped up” bullets cause much more severe wounds than direct hits. So if you

know that you must take bullets into account, which can not be stopped by the ballistic armor, be

always very alert with all your actions! Ballistic armor which was not designed for the expected

threat (examine the ballistic test protocols for vests of foreign manufacturers very carefully!) or if

their fibres are destroyed according to moisture, should not be worn for this specific task!

Trauma value

The trauma is the “indent” which the bullet creates upon hitting the ballistic armor. The depth and

diameter of this “crater” is mesasured. A great diameter implies a large areal distribution of the

shock effect. However this depth may not exceed certain threshold values. For concealable soft

ballistic armor a trauma depth of 40 mm is authorized. At this value it is assumed that no long term

harm is inflicted. In the USA conducted tests revealed that trauma depths of even 60 mm normally

don´t lead to life threatening injuries. To prevent possible injuries, as little as possible trauma

values must be achieved. In general the trauma effectivness is over evaluated. Up until now no

case is known that somebody died from the effects of a too high trauma value. Nonetheless

ballistic armor which trauma values are mostly at the threshold value of 40 mm indicate low

reserves.

Number of Layers

After the hitting of bullets on the ballistic package the number of penetrated layers and the number

of undamaged layers are counted. Very important: The number of undamaged layers doesn´t

state anything about the true reserves of the vest.

Only one layer of ballistic material less and the whole protection could be completely lost. The

number of layers taken by itself is therefore no criterion for the selection of ballistic armor. It can

only be seen in accordance with the attributes of the fibre.

Protection

The protection quality is determined by the following parameters:

§ number of fabric/shield layers

§ attributes of the basic fibre

Concerning Aramid and PBO systems, additional aspects are important:

§ finish of the fibre e.g. Hydrophobation (protection against moisture)

§ type of stitching

Ballistic Edge Testing

Edge testing are called hits occuring at the edge of the ballistic inserts. At the official ballistic

testing only hits are taken into account, which are more than 7 cm or more away from the edge. At

the edge testing the materials differ tremendiously. Fabric type vests offer relevant protection

starting at 3 cm, shield vests already at about 1,5 cm. Hybrid vests are approximately somewhere

between that.

Shock Absorbers

Shock absorbers additionally reduce the trauma value (indent depth of hitting bullets).

Shock absorbers may only be used together with the panel, because solely used it cannot stop

bullets. Shock abosrbers are important at the spine, since here indents of 40 mm can result in

severe injuries.

Trauma Packs

Trauma packs are inserted in front of ballistic inserts and reduces, similar to shock absorbers, the

indent. The disadvantage of trauma packs is their thickness of about 70 mm. This makes them

very recognisable and the conceal advantage of the underneath worn ballistic armor is lost.

Stabbing Protection

In many cases, together with the ballistic threat, a threat with stabbing weapons is imminent.

Which protection must a stabbing protection system offer? In the technical guide line of the

german police command academy an energy level of 35 Joule is layed down.

This value equals the energy of a two sided edged dagger with a weight of 2.6 kg hitting from 1.35

m hight. This testing facility, comparable to a "Guilloutine", penetrates a 0.8 mm strong plate of

high grade steel.

Metal foils as stabbing protection are very disputed. Worn on the body they are bound around the

body along the body axis. Thereby the protective construction will be so highly stiffened, that the

wearing comfort is reduced dramatically. Additionally there is the problem, that these foils can

bend through uncarefull handling and this may result in damaging the structure of the body armor.

However ballistic systems exist which already offer a good material based stabbing hindrance.

Although they don´t fulfill the above mentioned highly set values of the techinical guideline, but

they can be measured as highly practicable.

A good solution are tailor made molded parts out of light metal, which are inserted before the vest.

This “combination body armor” offers beside a very good stabbing protection, also protection

against normal blunts combined with high maneuverability. These vest is therefore highly suitable

for confusing conflict situations and high volience potential, for example riots, sporting events or

demonstrations.

Stabbing protection inserts made of metal weave (like ring weave) , which are

inserted in front of the ballistic insert can shatter after a bullet hits and result in

grevious wounds.

V50-Test

This ballistic test is conducted under strictly regulated conditions of the protective system. It will be

tested with a pre set speed of the hitting bullet. If this speed is now steadily increased, at a certain

point the testing bullets will penetrate the system. By this you can determine the performance of

the protective system.

This speed is called limit speed. It is dependent on high statistic fluctuations and therefore it can be

measured only very crude.

If speed is increased further, you reach a speed where 50% of the bullets penetrate the ballistic

package and 50 % are stopped. This is called the v50 speed and can be measured much more

exactly.

But always keep in mind that these values cannot be calculated only derived from experimental

test. Tolerances in quality of the ballistic material, different hardness of the bullets, environmental

like temperature, moisture and air pressure lead to higher or lower fluctuations of the testing result.

Most statements of v50 values are only isolated cases, a so called spot check, by which the power

of this value results in a highly questionable statement. To compare the performance of different

systems you need a statistic, that means many v50 values were tested under the exactly same test

conditions over a longer period of time.

The protective impact of ballistic body armor can be reduced by many physical influences. On this

occassion don´t underestimate environmental influences like moisture.

UV-Influences

Against effects of sun rays HPPE fibres are only affected slightly, PBO and Aramid fibres however

very strongly. To prevent a disintegration of this fibre systems with parts of PBO and Aramid the

panels clothing should inside and outside feature a UV filter.

Moisture

Many wrong and correct statements regarding this subject were written over the last several years.

The core point is: “In which form can moisture decrease the protective performance of body armor

during daily use?”

Therefore you must take into account in which task cases moisture becomes siginificant, and how

the protective system is influenced thereby. In the following cases out of experience and practice

the question of moisture influencing the vests performance arises:

§ The panel clothing is damaged, is the moisture micro climate influencing the material?

§ A vest was wetted for several days after the flodding of the police station

§ A coast guard officer falls during a routine control with his body armor into the river.

§ Accidentally the ballistic panels of the vest were washed together with the outer shell

§ Does wearing the vest during rain result in any influences ?

With the subject of moisture you have to distinguish between two totally different effects. On one

hand based on physical basics tej formation of water pockets and on the other hand chemical

influences of moisture to the fibre stability.

If protective systems, without panel clothing, are dunkened into a water can, slowly but surely

water penetrates into the different layers of the package. Independent from material it is basically

only a question of time until waterpockets are forming between the layers. If bullets are hitting this

water pockets the frictional circumstances change dramatically and the protective system will be

penetrated. For practical use this means that independent from the material body armor which was

wetted over a longer period of time should be completely dried out before it is used again during

tasks. Much more important is the question of chemical influences on the fibre stability. HPPE

fibres act hydrophob (greek: hydro = water, phob = hating) and are therefore totally unaffected by

moisture.

Influencing the Ballistic Performance

In the case of PBO and Aramid fibres it is different. Moisture is literaly assimilated by this fibres and

the yarn loses stability. Today very good fibre finish (treatment of the yarn) is available, to protect

the fibre against moisture. Unfortunately the user has no possibility to compare the quality of the

finish and is therefore restricted to trust the vests manufacturer. Additionally the undamaged

condition of the panel clothing must be always regarded since many manufacturers reject liabilities

for effects resulting of damaged panel clothing.

Most critical are aramid shields (like GoldShield) which are now available on the german market.

Hereby moisture is “sucked” via capilary effects into the layers and can at this spots destroy,

unnoticed by the user, the constructions stability. Dependent on the finish of the yarn this process

takes faster or slower place. Aramid shield is therefore more sensitive to moisture than Aramid

fabric and must always reliably be waterproof covered.

Flame Stability

An always discussed subject is the flame stability of ballistic packages. In the case an officer is hit

for example by a molotov cocktail and this grenade like weapon burns really ten minutes on the

person, the officer suffered already so severe burning wounds, that a “Melting” of the ballistic

inserts will not be recognized by him or her, since the Grim Reaper already sold a ticket.

Aramid systems are unquestionable highly heat resistant but are often covered with PVC foils for

moisture problem purposes. Upon burning of this foils produce corroding gases (hydrochlorid

acid) and possibly also highly toxic burning products like furanes and dioxines. This is the reason

why flame stability provides no decision criterion for concealable body armor. For tasks where you

must concern “fire” attacks, the wearing of task overalls with flame impregnated outer material

should be taken into account. Together with the police forces from Hamburg, Germany tests were

conducted to study the burning behaviour and effects of body armor and the results confirmed the

above statements.

Heat Resistance

Sometimes threatening news are heard, that body armor melts on the hood. HPPE has a heat

resistance of 150°C, Aramid about 550°C and PBO about 650°C. None of this fibres can therefore

be harmed by normal temperatures of a hood. Inside of a car maximum temperatures of 100°C can

develop. At this levels none of the fibres will be destroyed. Keep in mind that the last statment

concerns air and not body armor temperature. A complete warm up of the vest to 100°C affords a

much higher environment temperature. To exclude a burning of the own body, the vests

temperature should not be higher than 45°C. In comparison at the official ballistic testing institute

the stopping performance is tested at 70°C. Heat resistance is therefore no criterion for buying

body armor. Since the above mentioned fibres only heat up very slowly, the vest is no obstacle to

save for example somebody out of a burning building.

Aramid Fabrics

The data and attributes for the Aramid fabrics Kevlar and Twaron are summarized in the following

overall view

Criterion Explanation

Trademark Aramid is being produced under the trademark Kevlar (DuPont) and Twaron

( Acordis)

Construction An Aramid fabric system consists of about 25 to 35 layers, dependent on the

yarn type and finish.

Weight Aramid fabric systems are according to their higher density heavier in

comparison to comparable HPPE systems.

Wearing Comfort Protective constructions made of Aramid fibres are relativly soft. An optimized

wearing comfort can only be achieved through tailor made production.

Stabbing Aramid fabric offers some kind of stabbing protection. Upon entering of

Protection the stabbing weapon although a large portion of the fibres get pushed

away, and therefore it is advisable to include extra stabbing protection in

this categorie.

Moisture When buying such a vest a good hydrophobation must be guaranteed.

Ballistic Aramid systems are very good in protecting against 9 mm Para bullets.

Protection Generally the same protection like with a HPPE system can be achieved with

an Aramid system. For this goal you can for instance increase the number of

ballistic layers.

Ballistic Edge Starting at about 3 cm you receive notable stopping power. The soft fabric

Testing shows weaknesses, that means bullets can be “slipped” from the edge.

Stabbing Protection

If the protective packages are damaged with stabbing weapons you must immediately swap the

ballistic inserts. Otherwise no sufficient protection against bullets at the point of incision can be

guaranteed.

The following chapter will discuss the most important features of the different materials, which are

used for ballistic body protection at the moment.

HPPE Shields

The data and attributes of High-Performance-Polyethylen (HPPE) systems, Dyneema and

Spectra,are summarized in the following over view.


Tradename The fibres of HPPE-Shields are highly strong Polyethylene fibres (High

Performance Polyethylene). These fibres are available under the names of

Dyneema by DSM High Performance Fibres (Netherlands) or under license by

Honeywell (USA, former Allied Signal) as Spectra fibres. The HPPE-fibres offer

in comparison to aramid fibres a higher strength and stability.

Construction Honeywell (Allied Signal) transfered the shield technology from

the aeronautical and aerospace branche into the ballistic section. With this

construction the fibres are turned in an 90° angle towards each other, put

in order and pressed together with a foil from top and bottom.

Weight According to the higher strength of the yarns the weight of a HPPE vest can in

general be lower than comparable Aramid vests.

The weight is automatically dependent on the protected area. Nowadays an 2 3area weight of under 49 g/dm .The density of HPPE is lower than 1kg/dm ,

therefore HPPE inserts swim on water. This can be important for officers in

coastal areas or aboard of ships.

Wearing Comfort HPPE constructions mould during the course of time to the shape of the

individual body. To accelerate this process, BSST developed a production

process, which increases wearing comfort significantly right from the beginning.

The so altered material is sold on the market under the tradename of

DyneemaFlex.

Stabbing In difference to fabrics all fibres of a shield system must be cut, since they

Protection can not be pushed apart. Therefore HPPE shields offer a material own

practicable stabbing hindrance.

Moisture HPPE fibres are not affected by moisture. The size cut layers can therefore be

inserted without an outer clothing. But for easier maintanance/ handling they are

inserted into a light clothing.

Ballistic The energy assimilation of HPPE shields is very good.

Protection Therefore you achieve a good stopping power and trauma values despite a low

weight.

Ballistic Edge Starting at about 1,5 cm you receive notable stopping power.

Testing

The data and attributes of Aramid shields are summarized in the following overview.


Tradename Aramid shields are sold under the brand GoldFlex

System The layer number varies between 24 and 35

Wearing Comfort Vests made of Aramid shields are in comparison to HPPE systems

of the same type a little bit more stiff and heavier.

Stabbing The stabbing protection can be compared to that of HPPE fibre layered

Protection construction.

Moisture Since Aramid reacts hydrophil, that means it attracts moisture, Aramid shields

must be protected very well against moisture for all reasons (For further

explanation see chapter “Moisture”). Like with Aramid fabrics always guard

the unscathed panel clothing!

Ballistic The protection value can be compared to that of HPPE shields.

PBO is available on the market since only a short period of time and is sold under the tradename

Zylon. The attributes are detailed in th following lines.


Tradename PBO fibres are offered by the japanese Toyobo enterprise under the tradename

Zylon.

Stiffness PBO fibres offer considering their weight the highest stiffness of artificially

produced fibres.

Wearing Comfort According to the high stiffness of PBO very light systems can be constructed.

The material is very soft, therefore the trauma values are a little poorer.

Moisture PBO fibres have similar moisture attributes like Aramid fibres.

UV Resistance PBO fibres are more vulnerable to UV influences than Aramid.

Price PBO fibres are worldwide produced in very low quantities and are therefore still

very expensive. Body armor made of Zylon which are momentarily offered on

the market therefore only include small amounts of Zylon. Ballistic

improvements are slightly measurable at the best.

Aramid Shields

PBO Fabric

Hybrid Systems

The data and attributes of hybrid systems are summarized in the following overview.


Weight The area weight of hybrid systems is dependent on the mixing ratio of the used

ballistic materials.

Wearing Comfort With the construction of hybrid systems you must always weigh up

protection against comfort.

Stabbing To achieve a high stabbing protection a large portion of shield must be included.

Protection

Moisture Upon mixing with Aramid and PBO yarns the moisture reaction eqauls those of

similar Aramid/PBO systems.

Ballistic With hybrid systems interessting constructions can be developed for specific

Protection ammunition types.Through the inhomogenious stiffness you achieve time

related effects. With the choice of certain materials the hitting behaviour of the

bullets can be influenced. BSSt for example offers a hybrid solution which stops

Action 3 ammunition.

Guarantee Since different yarn manufacturers are involved, the vest manufacturer stands

on this point by itself. Appropriate herefore is to choose the guarantee time of the

most vulnerable component.

Compromise Why are there so many hybrid vests on the market?

Hybrid systems are mostly offered out of marketing reasons. The mentioned

advantages of this systems are most of the time not obvious and

understandable to the customer and in comparison to other manufacturers not

the same product but a total different one is offered. For example if a high

quality shield is mixed with a cheaper fabric you will achieve

a higher flexibility at the cost of protection, security or weight, in accordance with

lower production costs.

Generally said:

You are not combining only advantages but also the disadvantages of the

components!

Comparison of the Systems

The following table compares in shortened form all the before described systems in the way they

are normally offered on the market. The normal datas and attributes were taken into account.

While reading the table always keep in mind: “No advantage without disadvantage!”

The following chapter discusses the certificate for providing evidence for protective values of

ballistic armor. Take your time reading the ballistic test protocol which was delivered together with

your vest.

The technical commission of AK II at the police officers academy will publish the technical

guidelines for ballistic armor. This guideline defines the standards and demands for protective

vests. The american guideline is issued by the NIJ, the National Institute of Justice. German

demands and standards differe considerably from american. This is based on the different threat.

While in the USA heavier and softer bullets are the norm, in Europe smaller, tougher and faster

bullets must be taken into account.

Trademark

Aramid fabric

TwaronKevlar

-

+o (4)o (1)+o (1)o (1)- (2)o (3)+

DyneemaSpectra

++o (4)++++++++++++

GoldFlex

+o (4)+++++++-- (5)- (3)+

Zylon

++o (4)o+oo- (2)- (3)++

oo (4)o+oo- (2)- (3)++

Hybrid HPPE shield. Aramid shield

PBO fabric

WeightWearing comfortStabbing protectionEnergy assimilationBallistic edge testingBallistic angle testingInfluence of moistureInfluence of UV raysHeat resistance

(1) with a high share of shield material : + - = not sogood suited (2) with good hydrophobation : + o = sufficient(3) with UV-safe panel clothing : + + = good suited(4) with individual contour : ++ ++ = very good suited(5) ????????????

Technical Guideline

(*) Only when the system description states “loose” the

ballistic package and not the quality of the foil welding

machine was tested !

Correction sheet of the test report withthe clients and manufacturers entry

5 shots at 90° angle(straight shelling)

3 shots at 25° angle(angled shelling)

3 shots at 90° angle and70°C temperature

3 shots at 90° angle at-20°C temperature

3 shots at 90°angle andset on (100N)

3 shots at 90° angle andprewatered panel (*)

How should a ballistic test protocol be read?

The following graphic highlightens the most important informations and describes them

The ballistic test protocol

Respectable manufacturers will provide complete ballistic test protocols without any extra cost for

the customer. But you always have to keep in mind that the ballistic test protocol only reflects a spot

check. The following should be included in the protocol:

Velocity of the bullet

Angle of incidence Depth of the indent

Location of the bullet

Description of the package

Areal weight

What type of bullet was tested ?

At what distance was tested ?

Temperature of the panel

Where was tested ? When was tested ?

10 Kg

How to wear a body armor ?

Overlapping

Sitting

Freedom of the Arms

The following text describes what you have to keep in mind, when you wear an ballistic armor. With help of some features you can easily determine if the fit is optimal.

Bring front and back part to an overlapping and close the four velcro fastenings.Here you have to consider that the velcro fastenings are not too thightly fixed.You should wear the vest so that even physical stressful activities, like fast running that lead to an increased breathing can be done without any hindrance. The lateral overlapping for an all around protection should be at least 3 cm.

Neck & Throat Area

Set the pointing finger to the throat colliery and the ring finger should now touch the upper edge of the vest.

Front Panel

Adjust the front part in a manner, that it fits along the longitudenal axis of the body

. symmetrically

With concealable body armor you are always dependent on a compromise between protected area and wearing comfort. With the shortened vest length no hindrances occur during carrying out daily routine tasks and therefore the armor can be worn for hours without any problems. The reduced protected area can be neglected, since based on statistical surveys, the enemies reticule focuses the heart area. However for this instance the vest must be worn covered.

While sitting a compression of the body occurs according to the bending of the spine. This compression is individuallly different and can be up to 15 cm. The lenght of a concealable body armor must therefore be evaluated while you are sitting. The distance between the vests lower edge and belt should upon sitting be about 1-2 fingers. With this measurement it is guaranteed that the vest is not pushed upwards and chokes the throat during seated times.

Finally the arm sector is evaluated considering maneuverability. The closing of both hands with extended arms, for example steering a car, should be possible without any problems.

German Sources

N.N. Technische Richtlinie Schutzwesten. publisher:

Technische Kommission des AK II, Polizeiführungsakademie,

Forschungs- und Entwicklungsstelle für Polizeitechnik, Münster.

Göhl, A. Twaron in Ballistic Protection, internal documentation, Akzo Nobel,

Wuppertal

Sellier, K. Trauma-Effekte bei Schutzwestenträgern, Anhandlung, Institut für

Rechtsmedizin, Bonn

Sellier, K. Schußwaffen und Schußwirkungen I, Ballistik, Medizin und Kriminalistik

Max Schmidt-Römhild, Lübeck, 1977

N.N. DIN 31004, Begriffe der Sicherheitstechnik

Hogenboom,E.H. PE-Fasern für leichten ballistischen Schutz, Chemiefasern

van Dingenden, J. /Textilindustrie , 41./93.Jahrgang, Mai 1991

Schulz,G. Ballistischer Schutz mit Geweben aus Para-Aramid, Firmenschrift,

Böttger, Ch. Mehler Technische Textilien, Fulda

Restle,S. Ballistische Schutzwesten und Stichschutzoptionen,

Kabinett Verlag,1997

Brugger,R. Seminararbeit im Wahlpflichtfach “Optimierung der Mann-

Opferkuch,S. /Frauausstattung” Fachhochschule der Polizei Villingen-Schwenningen

Gulde,O.

Damm,H.-R. Wieviel Sicherheit bieten Schutzwesten? Polizeispiegel 11/96

Damm, H.-R. Ballistischer Personenschutz für die Polizei, Referat 1993

Kleser, M. “Überlebenshilfe”, Deutsches Waffenjournal 5/1997, S.758ff.

Ballistic Protective Systems

BSSt Sicherheitstechnik GmbHWalter-Herzog-Str.19D-89191 Nellingen

Fon +49-7337-9222-14Fax +49-7337-9222-19eMail [email protected] www.bsstgmbh.de

© copyright 2000 BSSt Baumann & SteffenSicherheitstechnik GmbH

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