When searching for equipment that will be deployed in demanding environments, you will likely encounter a variety of terms used to classify and describe that equipment. Some of these terms are used interchangeably, even though they refer to different types of equipment and protection methods. One common example is the use of “Blast Proof” and “Explosion Proof,” which are often confused despite describing very different types of protection. While the terms may sound similar, they are intended for completely different applications.
Understanding the distinction is critical when selecting cameras, monitoring systems, and other equipment for industrial, military, energy, and critical infrastructure applications. Selecting the wrong type of equipment can lead to unnecessary costs, compliance issues, or equipment that is simply not suited for the environment.
What Does Blast Proof Mean?
Blast Proof most often relates to military, defense, and critical infrastructure applications. The term refers to equipment that is designed to withstand the effects of an explosion occurring nearby. Unlike explosion-proof equipment, which is designed to contain an internal explosion, blast proof equipment is intended to withstand forces originating outside the enclosure.
There is no defined testing standard for blast-proof equipment. While testing is possible, the ability of the equipment to resist (or perhaps survive) a blast is a function of factors such as:
- Size and type of the blast
- Distance from the blast
- Peak pressure from the blast wave (overpressure)
- Impulse pressure (occurs over time)
- Required equipment functionality post blast
Because blast events vary significantly, equipment performance is typically evaluated against a specific set of test conditions rather than a universal “blast-proof” standard.
Therefore, for a piece of equipment designated Blast Proof, what you may see in a specification is something like:
- Can withstand an overpressure of xx psi (such as 10 psi) per MIL-STD-810
- Shock resistant to a specific rating based on MIL-STD-810, Method 516.x
- Statement that the equipment remains fully functional following the test
For most applications, “Blast Resistant” is a more accurate term than “Blast Proof.” The term blast resistant more accurately reflects the fact that equipment can be designed and tested to withstand certain blast conditions, but not necessarily every possible blast scenario.
Typical applications for blast-resistant equipment include:
- Military facilities
- Defense installations
- Ammunition storage areas
- Government infrastructure
- Petrochemical facilities concerned with external blast events
What Does Explosion Proof Mean?
Explosion Proof is completely different and applies to equipment deployed in potentially explosive environments.
Using “Flameproof” (the most common method of protection for industrial equipment) means the equipment enclosure is designed to contain an internal explosion. For example, if a flammable gas or vapor enters the enclosure and ignites, the enclosure is designed to contain the resulting explosion and prevent flames or hot gases from igniting the hazardous atmosphere outside the device.
In other words, explosion-proof equipment is not designed to withstand an external blast. Instead, it is designed to prevent the equipment itself from becoming an ignition source.
Equipment that is rated Explosion Proof will include a label identifying the specific standards met following testing. During the certification process, testing laboratories create multiple explosions inside the enclosure to verify compliance. There are many different ratings for different applications, including Class I, Division 1 (C1D1), Class I, Division 2 (C1D2), ATEX, and IECEx. These certifications define where equipment can be safely installed and what types of hazardous gases or vapors may be present.
The specific certification required often depends on the geographic region where the equipment will be installed. For example, ATEX is commonly used throughout Europe, IECEx is recognized internationally in many regions around the world, and Class/Division or Class/Zone standards are typically used in North America and certain countries in South America.
Because certification requirements vary by region and application, it is important to verify the standards applicable to the location where the equipment will be installed. A rating accepted in North America may not be recognized in Europe, while another may be commonly accepted throughout the Middle East.
When evaluating explosion-proof cameras or other hazardous-area equipment, it is important to determine which standards the equipment has been tested and certified to. You should also verify the certification required for the intended installation location, which may require consultation with your facility manager, safety team, or insurance provider.
Despite the differences between standards, several common tests are performed across most explosion-proof certifications, including:
1) Ignition Test
This test depends on the type of hazardous materials present in the surrounding atmosphere, including flammable gases, combustible dusts (such as grain or aluminum), and certain fibers (such as cotton or wood). The equipment is placed inside a chamber containing a representative atmosphere, and a specific mixture of the worst-case hazardous environment is introduced into the enclosure and repeatedly ignited. If the surrounding chamber atmosphere ignites, the equipment fails the test.
2) Over-Temperature Test
Equipment is evaluated for operation across its rated temperature range. A functional sample is brought to its maximum temperature rating while operating inside a test chamber. Because the internal temperature of the enclosure may be higher than the surrounding environment due to waste heat, critical components are evaluated to ensure they do not exceed allowable temperature limits.
3) Impact Test
A specified weight is dropped onto the equipment from a specified height. The test laboratory will target the most vulnerable area of the enclosure, such as a camera viewing window, for impact. While the impact may not penetrate the enclosure, any damage that compromises the enclosure’s integrity, such as a cracked viewing window, may result in a failure.
4) Ingress Protection Test
The equipment is exposed to a controlled, high-volume stream of water from a specified distance and for a specified duration. Following the test, the enclosure is opened and inspected for water intrusion. Even a single drop of water inside the enclosure is considered a failure.
Common explosion-proof applications include:
- Oil and gas facilities
- Refineries
- Chemical plants
- Pharmaceutical manufacturing
- Fuel storage terminals
- Grain handling facilities
- Mining operations
Comparison Chart: Blast Resistant vs. Explosion Proof
| BLAST RESISTANT | EXPLOSION PROOF |
|---|---|
| Designed to withstand the effects of an external blast event | Designed to contain an internal explosion |
| Common in military, defense, and critical infrastructure applications | Common in oil and gas, chemical, and industrial applications |
| Evaluated against specific blast conditions and performance requirements | Certified to hazardous-area standards such as ATEX, IECEx, and Class/Division |
| Protects equipment from external forces | Prevents equipment from becoming an ignition source |
Why the Difference Matters
One of the most common misconceptions is that an explosion-proof camera or enclosure is automatically blast proof. This is not the case.
An explosion-proof camera may safely contain an internal ignition event, but it may not be designed to withstand the extreme overpressure associated with an external explosion or military blast event.
Likewise, a blast-resistant enclosure may survive a pressure wave but may not meet the hazardous-area certifications required for installation in a classified location.
Before selecting equipment, it is important to determine whether the primary concern is:
- Preventing ignition in a hazardous atmosphere
- Surviving an external blast event
- Both
The answer will determine the design requirements, certifications, and equipment selection.
Examples of Explosion-Proof Industrial Cameras
Industrial Video & Control (IVC) offers a variety of explosion-proof cameras for hazardous industrial environments. These cameras are commonly used in oil and gas facilities, chemical plants, refineries, and other locations where certified equipment is required.
One example is the AMZ-HD41-3, a compact Class I, Division 1 IP camera designed for hazardous-area video monitoring. Its small footprint makes it well suited for installations where mounting space is limited.
For applications that require greater coverage and operational flexibility, IVC also offers the APTZ-3045-09 explosion-proof PTZ camera. Rated Class I Division 1, the APTZ-3045-09 provides remote pan, tilt, and zoom functionality, allowing operators to monitor large areas with a single camera. Its explosion-proof design makes it well suited for refineries, chemical processing facilities, oil and gas operations, and other hazardous industrial environments.
Additional Explosion-Proof Camera Solutions
In addition to the AMZ-HD41-3 and APTZ-3045-09, IVC offers a complete line of explosion-proof cameras, including fixed IP cameras, PTZ cameras, thermal cameras, and analog camera solutions for Class I Division 1, ATEX, and IECEx applications.
Selecting the Right Equipment
When evaluating surveillance equipment for harsh environments, it is important to avoid using the terms “blast proof” and “explosion proof” interchangeably. Before you make a decision, consider these questions:
- Is the equipment being installed in a classified hazardous location?
- Is there a risk of flammable gases, vapors, or combustible materials?
- Is there a requirement to withstand an external blast event?
- What certifications are required by site safety standards?
- What level of operational functionality must be maintained following an incident?
The answers will help determine whether explosion-proof, blast-resistant, or another specialized equipment design is required.
Conclusion
Although the terms are often confused, Explosion Proof and Blast Proof describe two fundamentally different types of protection.
Blast-resistant equipment is designed to withstand the effects of an external pressure wave or explosion event. Explosion-proof equipment is designed to contain an internal ignition and prevent it from igniting a hazardous atmosphere surrounding the equipment.
Understanding this distinction is critical when selecting industrial cameras and other equipment for demanding environments. By matching the equipment design to the actual hazard, organizations can improve safety, maintain compliance, and ensure reliable operation in even the most challenging applications.
Learn more about IVC’s explosion-proof cameras.
About the Author: Bill Richards is the co-founder and Vice President of Operations at Industrial Video & Control. He leads the company’s hardware engineering efforts and has over 25 years of experience developing products for hazardous areas. Among his accomplishments, Bill pioneered the industry’s first line of IP dome cameras certified for use in hazardous areas. Bill holds a bachelor’s degree in engineering from the University of Michigan.