The terms &#;blast-proof&#; and &#;explosion-proof&#; are widely used within the shield enclosures and protective materials industry. Our customers often ask for a &#;bulletproof&#; enclosure or an &#;explosion-proof&#; shielding room. Many visitors arrive at our site by using these search terms.
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While the phrases are commonly used, we strive to use the correct vocabulary. Let&#;s be straightforward: there&#;s no such thing as a blast-proof product. Keep reading and find out why you should avoid using these terms.
It may sound nit-picking, but the terms &#;blast-proof&#; or &#;explosion-proof&#; imply that something can be made impervious to any type of explosion. The reality is that currently, no material nor product can resist damage from a large enough blast or explosion.
There is similar confusion about the term &#;bulletproof.&#; Manufacturers of &#;bulletproof vests&#; quickly point out that their products are only rated to stop bullets of a specific mass and velocity, and then only when the product is otherwise in new condition and has not been previously impacted. A bulletproof vest might be rated to stop a 38 caliber bullet, but if a second bullet impacts the vest near the first strike, the vest might fail.
In other words, all shielding materials could fail under different scenarios. It would only take different conditions on the testing, such as a bigger blast or caliber bullet, to affect a product&#;s performance.
For a product to be considered blast, bullet, or explosion-proof, it should be able to contain any type of blast regardless of the conditions surrounding it.
A blast-proof material should withstand any type of blast regardless of the conditions. Such material doesn&#;t currently exist.We prefer the terms &#;blast-resistant&#; and &#;explosion-resistant,&#; and you will see these terms used on our website and literature. While no shielding room, shield enclosure, or shielding blanket in the market can be blast-proof, they can be blast-resistant if engineered and tested to safely contain a specific amount of energy before failure.
For this reason, we prefer using the term blast-resistant or explosion-resistant for our shielding solutions.
A common use of TotalShield blast-resistant enclosures is to protect staff while testing a component using compressed air. These components can rupture under pressure, resulting in a violent release of energy, a &#;blast wave&#;, and debris. See our blog about the Differences between pneumatic and hydrostatic pressure testings to learn more about it.
For our explosion-resistant enclosures, we design them for possible explosions related to chemical reactions &#; for example, the ignition of flammable gas or other explosive chemical reactions.
To make this slightly more confusing, people also use the term &#;ballistic-resistant.&#; It expresses a similar idea to &#;bulletproof&#; / &#;bullet-resistant.&#; Ballistic-resistant refers to the ability to protect against an object in flight. TotalShield customers often work with equipment that might send an object flying under a failure scenario.
Think of a spinning turbine that expels fan blade fragments at high speed upon failure or a centrifuge that fails and sends its payload outward at high velocity. These objects are traveling ballistically, and we can engineer shielding products that can withstand the impact of these high-speed and potentially lethal objects. While they are not bullets, you can think of them as acting like a bullet, and just like a &#;bulletproof vest&#;, our shielding products are designed to stop the object before it causes injury.
In the following video, you can see one of the tests we have conducted for ballistic impact. You can watch as the polycarbonate panel is impacted by a 32-pound steel projectile traveling at 85 feet per second.
The panel dissipates energy by first moving in the proprietary TotalShield gasketed frame and then deforming elastically. Our manufacturing processes avoid any stress points, protrusions, or polycarbonate incursions that might concentrate stress or strain forces and result in failure of the panel.
There are a few different blast resistance standards for windows and buildings, and bullet resistance standards for bullet-resistant products such as security glass and security barriers.
The table below summarizes some of the existing standards.
StandardDescriptionNIJ Standard .01&#;Ballistic Resistant Protective Materials&#;&#;The purpose of this standard is to establish minimum performance requirements and methods of test for ballistic-resistant protective materials.&#;UL 752&#;Standard for Bullet-Resisting Equipment&#;&#;1.1 These requirements cover materials, devices, and fixtures used to form bullet-resisting barriers which protect against robbery, holdup, or armed attack such as those by snipers.1.1.1 This standard can also be used to determine the bullet resistance of building components that do not fit the definition of equipment, such as windows, walls, or barriers made out of bullet-resistant materials.1.2 As used in these requirements, the term &#;bullet-resisting&#; signifies that protection is provided against complete penetration, passage of fragments of projectiles, or spalling (fragmentation) of the protective material to the degree that injury would be caused to a person standing directly behind the bullet-resisting barrier.&#;ASCE 59-11:&#;Blast Protection of Buildings &#; Blast-Resistant Design of Systems, and Components&#;&#;Blast Protection of Buildings provides minimum requirements for planning, design, construction, and assessment of new and existing buildings subject to the effects of accidental or malicious explosions. The Standard includes principles for establishing appropriate threat parameters, levels of protection, loadings, analysis methodologies, materials, detailing, and test procedures. It provides a comprehensive presentation of current practice in the analysis and design of structures for blast resistance. Commentaries on the requirements are also included. The Standard supplements existing building codes, standards, and laws, but is not intended to replace them.&#;These standards, however, aren&#;t directly applicable to an industrial setting.
For example, a customer that uses a high-speed centrifuge and wants to provide a safety enclosure to protect against a possible machine failure is not really looking for a bulletproof or blast-resistant enclosure. Instead, they are looking for a ballistic-resistant enclosure that can protect staff from the failure of the centrifuge, taking into account the speed of the centrifuge and the size and mass of the centrifuge payloads.
That is why every TotalShield product is custom-designed by our engineers to protect against a defined threat level. In the example given above regarding a high-speed centrifuge, our engineers would work with the customer to understand the following:
Using these data points, our engineers analyze the ballistic energies associated with multiple failure modes and design an enclosure that will reliably protect personnel in the event of a machine failure.
Each product is delivered with a Letter Report that details the design methodology and analysis used, the specific assumptions made, and calculations used; it also includes references to material manufacturer testing and TotalShield&#;s proprietary test archive compiled over 25 years.
You can find an example of our proprietary testing used in designing a ballistic-resistant shielding room below:
&#;TotalShield has impacted 1/2 inch thick polycarbonate mounted in our proprietary framing with a 32 lb steel projectile traveling at 85 ft/s, which corresponds to an impact energy of approximately ft lb ( J).&#;
Our customers engage in a number of different activities across many industries: designing rocket motors, engineering turbines, running power generation equipment, or maintaining heat exchangers. They all share one thing in common: they care about the safety of their employees.
So while our customers might use the terms &#;bulletproof&#;, &#;blast-proof&#;, &#;ballistic resistant&#;, or &#;explosive resistant&#; interchangeably, we know what they mean. They want to keep their people safe. At TotalShield, we will work with your staff to define and quantify the threat and then design a custom solution that will do just that.
According to GOST .1- &#; Non-electrical equipment for potentially explosive atmospheres&#; the equipmentexplosion-proof equipment should be marked in a visible place on the main part of the equipment. The marking must be clear and durable, even in case of possible chemical corrosion.
a) manufacturer&#;s name and address;
b) equipment type designation;
c) year of equipment manufacture;
d) designation of the group and explosion protection level of equipment (Group I, with Ma or Mb explosion protection levels - for use in underground mines and their surface structures, hazardous as to firedamp and/or combustible dust; Group II, with Ga, Gb, Ge explosion protection levels Group III, with Da, Db, Dc explosion protection levels - for use in hazardous areas of premises and outdoor installations, except for underground mines, pits and their surface structures);
e) designation of explosion protection type indicating that the equipment complies with one or more of the types of explosion protection
The following symbols for the types of explosion protection should be used:
&#;fr&#; - enclosure with limited gas passage;
&#;d&#; - flameproof enclosure;
&#;c&#; - structural safety;
&#;b&#; - control of the ignition source;
&#;p&#; - high blood pressure;
&#;k&#; - liquid immersion;
&#;g&#; - inherent safety;
f) designation of group and subgroup of equipment:
&#;I&#; - for equipment intended for use in underground mines and their surface structures, hazardous as to firedamp or combustible dust;
&#;II&#; or &#;II&#;&#;, or &#;IB&#;, or &#;II&#;&#; - for equipment intended for use in places with a potentially explosive gas atmosphere, except for mines and their surface structures, hazardous as to firedamp or combustible dust. The letters A, B, C are used if it is prescribed by the standard for a specific type of explosion protection.
If the equipment is intended for use with a specific gas only, the designation &#;II&#; must be followed by the chemical formula or name of the gas.
Note - Equipment marked IIB is suitable for use in places where equipment of subgroup IIA is required. Equipment marked IIC is suitable for use in places where equipment of subgroup IIA or IIB is required.
If the equipment is intended for use with a specific gas only, the designation &#;II&#; must be followed by the chemical formula or name of the gas.
NOTE - Equipment marked IIB is also suitable for use in places where equipment of subgroup IIA is required. Likewise, equipment marked IIC is also suitable for use in places where equipment of subgroup IIA or IIB is required.
&#;III&#; or &#;III&#;&#;, or &#;IIB&#;, or &#;III&#;&#; - for equipment intended for use in places with a potentially explosive dust atmosphere, except for mines and their surface structures, hazardous as to firedamp or combustible dust.
NOTE - Equipment marked IIIB is suitable for use in places where equipment of subgroup IIIA is required. In a similar way, equipment marked IIIC is suitable for use in places where equipment of subgroup IIIA or IIIB is required.
g) for Group II equipment - designation of the temperature class or maximum surface temperature, °C, or both. If both values are included in the marking, then the temperature class should be indicated last in parentheses. The temperature class or maximum surface temperature is not marked on the equipment fittings.
Example - T1 or 350 °C or 350 °C (T1).
Group II equipment with a maximum surface temperature exceeding 450 °C should include only the temperature value.
Example - 600 °C.
Group II equipment intended for use in a specific gas does not need to be marked with a surface temperature value.
For Group III equipment - designation of the maximum surface temperature value, °&#;, preceded by the T sign; the degree of protection provided by the enclosure.
Example - T110 °C;
Example - IP54.
If the actual maximum surface temperature does not depend directly on the equipment, but mainly on the operating conditions (such as the heated liquid in the pump), then the temperature class or surface temperature is allowed not to be included in the marking. Such situation should be reflected in the marking, and the corresponding information should be provided in the manual for the consumer or the operation manual.
h) ambient temperature designation for Group I, Group II and Group III equipment (if applicable) as shown in Table.
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Ambient temperature designation:
Equipment Ambient temperature range during operation Temperature designation Normal Maximum 40 °&#;,i) serial number, excluding:
- fittings (bushings, locking plates, fixing plates);
- small-sized equipment with a limited surface (the batch number can be considered as an alternative to the serial number);
j) name or mark of the certification body and certificate number - if the equipment is certified; number of the &#;technical file&#; (technical documentation), assigned by the manufacturer - if the equipment is not certified;
k) special conditions for safe use, if necessary. In this case, &#;X&#; must be placed after the explosion protection mark or the &#;technical file&#; number. A warning notation can be used instead of &#;X&#;.
NOTE The manufacturer should provide the consumer with information on the requirements of special conditions for safe use, together with other necessary information contained in the manual for the consumer or in the operation manual;
l) any other additional marking prescribed by the standards for the specific types of explosion protection listed in section 1;
m) any marking required by the specific equipment standards.
If the equipment is intended for use in an explosive atmosphere containing gases, vapors, mists or dust, the marking should include designation of appropriate levels of equipment explosion protection. In case of using different parts of equipment with different types of explosion protection, each corresponding part in the marking must have a designation of the type of explosion protection adopted therefor.
If several types of explosion protection were used in the equipment, designation of the main type of explosion protection is put in the first place, and then that of other types.
On small equipment with a limited surface, the content of the marking can be reduced, but, nevertheless, the marking must include the name or registered trademark of the manufacturer and the following:
a) designation of the explosion protection type;
b) name or mark of the certification body;
c) certificate number;
d) &#;X&#; mark, if applicable.
Example for Group II equipment with Ga explosion protection level for operation in an explosive gas atmosphere for a long time, using two independent types of explosion protection, one of which remains active even in case of rare faults. Two independent types of explosion protection are &#;structural safety protection &#;c&#; with a maximum surface temperature of 135 °C (T4) and &#;liquid immersion protection &#;k&#;&#;:
- manufacturer&#;s name and address;
- type of equipment and year of manufacture;
- group and explosion protection level of equipment, II Ga ;
- type of explosion protection and temperature class, &#;/k T4;
- serial number;
name or mark of the certification body and certificate number.
NOTE There is a &#;/&#; sign between the two independent types of explosion protection.
Example for Group II equipment with Gb explosion protection level for operation in an explosive gas environment using two types of explosion protection on different parts of this equipment. Two types of explosion protection are &#;structural safety protection &#;c&#; with a maximum surface temperature of 135 °C (T4) and &#;liquid immersion protection &#;k&#;&#;:
- manufacturer&#;s name and address;
- type of equipment and year of manufacture;
- group and explosion protection level of equipment, II Gb ;
- type of explosion protection and temperature class, &#;/k T4;
- serial number;
- number of the &#;technical file&#; of the manufacturer.
NOTE There is no &#;/&#; sign between the two combined types of explosion protection.
Example for Group II equipment with Gb explosion protection level and with type of explosion protection &#;flameproof enclosure&#; for use in an explosive gas atmosphere with gas of IIB subgroup, temperature class T4:
II Gb d IIBT4
Example for Group II equipment with Gc explosion protection level for use in an explosive gas environment with temperature class T4 without any type of explosion protection:
II Gc T4
Example for Group III equipment with Db explosion protection level and with type of explosion protection &#;constructional safety&#; for use in explosive dust environment with a maximum surface temperature of 110 °C and degree of protection IP54:
III Db c T110 °C
IP54
Example for equipment: Group II, Gb level of explosion protection with type of explosion protection &#;constructional safety &#;c&#;&#;, for use in explosive gas atmosphere with temperature class T2 and Group III, Db level of explosion protection with type of explosion protection &#;constructional safety &#;c&#;&#;, for use in potentially explosive dust atmosphere with a maximum surface temperature of 230 °C and degree of protection IP54:
II Gb &#; &#;4
III Db &#; &#;230 °&#;
IP54
Example for Group II equipment with two levels of explosion protection (for example, for different pieces of equipment):
II Gb d &#;3 / Ga with &#;2
The equipment should be supplied with user manual or operation manual, including at least the following:
- summary information included in the marking of the equipment, except for the serial number, as well as any additional relevant information to facilitate maintenance (for example, the address of the supplier, repair service, etc.):
- safety instructions;
- on commissioning;
- on operation;
- on assembly and disassembly;
- on maintenance (inspection, routine and emergency repair);
- on installation;
- on adjustment;
- indications of special hazards arising from the equipment, for example, in hazardous areas in front of pressure relief devices (if necessary);
- instructions for training (if necessary);
- details that allow a decision to be made whether the equipment can be used safely in the intended area and under the expected operating conditions.
NOTE This information is based on an assessment of the ignition hazards.
- values of pressure, maximum surface temperature and other limit values;
- special conditions for safe use, including details of possible misuse based on experience (if necessary);
- main characteristics of auxiliary devices that can complement the equipment (if necessary).
Manual for the consumer or the operation manual should contain information, drawings and diagrams necessary for commissioning, maintenance, inspection, verification of the correct functioning and, if necessary, repair of the equipment, along with recommendations to ensure the explosion safety of its operation.
WorldWideBridge team is always ready to consult you on this matter. Do not hesitate to contact our team. You can also send your inquiry through [ protected].
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