PART 3 of 3 – Bullet Resistance (Ballistic) and Blast Resistance & How to Choose a Level of Protection
Bullet Resistant (Ballistic)
It is sad to think that we live in a time where we need to design entrance solutions for keeping our families and property safe, but we must continually innovate to overcome the threats that present themselves in daily life. Bullet resistant doors or ballistic doors and complete ballistic-rated entrance systems are an important part of this innovation.
(We previously discussed in Part 1 the reason we don’t use the term “bulletproof door” when referring to these products.)
What makes a product bullet resistant? There are several ratings that could describe the level of bullet resistance in a product. The most common are:
National Institute of Justice (NIJ) 0108.01
State Department SD-STD-02.01
HP White Laboratories HPW-TP 0500.02
European Standard DIN EN 1063
British Standards Institution BS 5051
Councils of Standards Australia/New Zealand AS/NZ 2343
A certified test lab performs these tests in a controlled environment. The range of weapons varies from handguns to rifles, and the ratings are quite different depending on the standard to which you are testing.
For example, you may hear someone refer to “Level 3”, which has a different meaning depending on which testing standard you are talking about. Level 3, UL 752, calls for a .44 magnum handgun. National Institute of Justice (NIJ) Level 3 calls for the use of a 7.62mm (.308 Winchester) rifle. So, as you can see, there is a difference.
I have worked on several projects developing bullet resistant doors using a fiberglass pultrusion process. When deciding on a bullet resistant opening solution I strongly recommend exploring the pultruded ballistic door options that are available. Believe it or not, steel is not always the answer to solving these complex entrance problems. When used properly, fiberglass has excellent ballistic properties without the concern of deterioration due to rust or corrosion.
In some cases, such as in government installations, there is a blast requirement for most if not all exterior entrance systems. There are a couple of different approaches to achieve a blast rating for a blast-rated door specification.
Arena Testing- This is obviously the most fun. As you can imagine by the name, this testing occurs outside in a controlled area, by setting off explosives to achieve the desired load and duration. The entrance system is instrumented to record the forces felt during the explosion. The advantage of using an arena test is that you’re not limited to certain dimensions on the product you’re testing. The downside with this method is that it is more difficult to obtain a specific pressure and duration due to the variation in explosive behavior.
Shock Tube- The shock tube is an instrument used to replicate and direct blast waves at a sensor or a model to simulate actual explosions and their effects, usually on a smaller scale. The advantage of using the shock tube is that you can repeat the test more accurately than arena testing. The disadvantage is that the size of the shock tube restricts the size of the specimen.
How do I know what level of protection I needed for an entrance?
To be successful when ordering these types of systems, I strongly recommend that you take the time to understand the science behind the products that will protect you and your customers. Understanding the requirements of your state or local jurisdictions and having all the information ensures that you and your customer have on-time deliveries and products that meet the requirements for the project.
For example, the load results for HVHZ approved systems are calculated in pounds per square foot. With ballistic systems, you need to understand the caliber of bullet that your entrance must withstand in an attack. This information will dictate the level of protection required.
For blast-rated protection, you will need to know the blast load the product (in this case, a blast-rated door) needs to withstand, calculated pounds per square inch (psi), as well as the impulse calculated in pounds per square inch and milliseconds (psi-ms). For intrusion resistance, you need to know the amount of time that you want to hold a perpetrator at bay and if you want laminated glass or polycarbonate glazing.