Frequently Asked Questions

The best approach is to contact us at BS&B explosion protection and we will guide you through the explosion protection application engineering process relevant to your specific combustible dust application and aligned with any Codes and Standards such as NFPA and ATEX that may be appropriate to your facility. Typically, the starting point for combustible dust safety assessment is determined by the following information

• Details of combustible dust material(s) being handled including explosibility data (Kst and Pmax in particular)
• Equipment types to be protected such as dust collector, bucket elevator, conveyor, silo, or milling system along with dimensions and any known level of pressure resistance / design pressure. If equipment drawings are available this is ideal as long as they reflect the true construction including any internal obstructions
• Process operating conditions (pressure and temperature in particular)
• Details of interconnections to other process equipment or building compartments such as piping and ductwork
• Piping and Instrumentation Diagram (P&ID), if available
• Location of equipment (indoor, outdoor, position relative to outside walls or roof)
• Details of any existing explosion protection measures that may be present, such as explosion panels / explosion doors / spark detection and extinguishing systems / explosion suppression equipment

BS&B are always ready to support your in house team or your chosen installation contactor. Passive explosion protection devices such as explosion vents and flamefree vents require care an attention to their mechanical installation. Active explosion protection devices such as explosion suppression and fast acting knife gate valves require careful integration both mechanically and electrically. To facilitate your successful installation of explosion protection equipment, we provide detailed installation and operating instructions for you to follow, mounting hardware such as explosion vent frames or suppression system mounting brackets, remote technical support from our experienced team, documentation such as layout drawings and electrical wiring diagrams, and on-site commissioning field service for active explosion suppression and explosion isolation systems. Support of on-site meetings with mechanical and electrical installers both in person and online is recommended.

Changes to processes, such as modifications or additions to the existing equipment, changes to the process conditions, or changes to the materials being handled, require a review of the explosion protection design. A ‘management of change’ process is expected by industry Standards such as NFPA, OSHA, and ATEX. Any proposed changes must be reviewed with BS&B prior to implementation so that the intended combustible dust safety outcome is achieved.

BS&B can present options for combustible dust explosion protection which can then be assessed with respect to the preferences of the end user. The protection approach is often influenced by specific application conditions. For example, while explosion panels used for explosion venting purposes are the simple economic choice, their use indoors or in a crowded outdoor workplace with personnel sometimes present would not be recommended on account of the fireball generated during their activation. A vented explosion flame ball might reach more than 100 feet / 30 meters from the location of the explosion panel(s) such as when mounted to a large volume combustible dust storage silo. BS&B will work with you to understand the full application details of the available explosion safety solutions to arrive at the safety solution that is right for your needs.

Explosion vents can protect a wide range of equipment by relieving the explosive pressure generated during a deflagration. Assuming the flame ball released during explosion panel activation is accommodated in a safe area, there is another important facet of explosion protection safety that the BS&B team will guide you on. Preventing propagation of the primary combustible dust explosion event to interconnected locations is very important. For this reason, in addition to explosion venting, explosion isolation technology such as mechanical blocking valves and chemical isolation barriers is typically required.

In contrast to explosion venting, explosion suppression systems detect and suppress a deflagration in its early stage before destructive pressures are generated & before the full combustion process has developed. Consequently, thermal & mechanical damage to equipment is minimized and so are potentially toxic by-products of combustion. This enables equipment to be up and running quickly after a deflagration and without external release of the combustion process this protects personnel and the environment. Unlike conventional explosion venting, with suppression systems there is no external fireball creating the potential for secondary explosions and combustion. Explosion suppression systems such as the BS&B IPD system also conveniently accommodate the need for explosion isolation of connected ducting and piping by incorporating chemical extinguishing barriers which do not impede the flow of air in conveying ducts. Mechanical isolation devices placed into a pneumatic system will typically introduce pressure drop which has to be offset by the electrical fan system - a hidden expense that is easily forgotten when making combustible dust explosion protection equipment decisions.

Insurance companies typically recognize the reduction in risk associated with the implementation of explosion protection solutions. This may reduce the insurance premium or may be a condition of providing continued insurance.

Explosion venting devices such as explosion panels & explosion doors are intended to be inspected and not used in a ‘fit and forget’ manner. Explosion venting devices should be inspected according to local codes and standards, and in the absence of such direction, should be inspected annually or in accordance with the manufacturer’s installation and operating conditions (whichever comes sooner). National Fire Protection Association Standard NFPA 68 has provided an inspection check list for many years, and this is carried forward into its 2024 revision. Some of the key items are:

• Verify that product identification tags and labels remain legible
• Confirm that the design documentation is available
• Look for any indications of corrosion as this will impair the intended function of the safety device
• Look for product buildup on the venting device or within its construction that could impact its operation; weight added to an explosion venting device may cause it to open more slowly than intended which can lead to higher pressure than planned within the protected equipment
• Verify that seals such as gaskets continue to be present and remain in good condition
• Check for any modifications to the original explosion venting device such as painting over of the explosion panel, addition of silicone sealant that was not a part of the original device, obstructions in the path of the venting device that were not accounted for, or the introduction of any counterfeit components.
• Confirm that there any no obstructions or combustible materials in the potential path of a vent fireball; BS&B can provide a flame ball size estimation upon request.

NFPA 660 provides prescriptive solutions for explosion protection for specific process equipment and industries, and it also provides a framework for implementing explosion protection and prevention. NFPA 68 and 69 detail the requirements for the specific combustible dust explosion protection solutions available from BS&B which include venting, ducted venting, flameless venting, suppression and explosion isolation solutions including chemical extinguishing, flap valve, knife gate valve, and float valve technology. BS&B can assist you in navigating the NFPA standards in order to select an explosion protection solution.

Any industry which handles, processes, conveys or stores combustible dust has a potential need for explosion protection. This includes:

• Grain and Feed
• Food and Nutrition
• Petrochemicals such as plastics
• Pharmaceutical
• Coal handling in power, cement and steel production
• Wood processing
• Pigments
• Specialty chemicals
• Flavors and fragrances

The applications in which venting should be applied are generally outdoor locations that have a safe area for the flame ball that will emerge from the activated explosion vent(s) to disperse. This area should be free of personnel, equipment and other combustible materials. The flame ball can reach over 100 feet (30 meters). Its size is a function of the equipment volume that is being vented and the number of venting locations. Venting may also be safely applied with indoor equipment that is ducted to the exterior. Still, the exterior location must safely accept the flame ball that releases from the ducting upon explosion vent activation. BS&B can provide an estimate of the flame ball size for your application.

Assuming that appropriate corrosion resistant materials have been selected for the application in question, periodic inspection according to the requirements of NFPA 68 will reveal damage or deterioration that may occur in service. If such inspection reveals leakage of dust, it is possible that the explosion vent seal has been breached. Do not attempt to repair this seal. A leaking explosion vent must be replaced. Consult BS&B to review your observations and seek further recommendations.

It is not as simple as replacing a standard vent with a deflector or a Flamefree vent size for size because the vent efficiency of these devices will be lower than a standard explosion vent. The relief area needs to be recalculated and an appropriate location for the alternate venting technology identified. BS&B provide complimentary vent sizing according to NFPA and ATEX Standards.

Yes, adding a duct will likely increase the required relief area. Typically, there is a short distance of straight duct that is allowed with no effect, but as you increase the duct length, or add anything but a straight duct, it will increase the required relief area. It is important to explain your ducting needs when engaging in vent sizing. There will be applications that cannot be safely vented through a duct due to its length and configuration; consult BS&B for alternative solutions such as flameless venting or explosion suppression.

It is always a good idea to insulate your vent if the process temperature varies drastically from the exterior temperature. This will help keep your process temperature at the intended value as well as avoiding condensation of the inside of the process. This can create dripping, and unnecessary moisture buildup in the process. It may also create product buildup on the inside of the vent, which may affect the performance of the vent; an explosion vent heavily caked with accumulated product will open more slowly and typically lead to a higher than desired pressure upon activation which may not protect the equipment as intended.

BS&B needs to know if there is vacuum, and what that maximum vacuum is along with the degree of pressure cycling, the maximum possible positive pressure at the explosion vent location, maximum operating temperature, and whether vent insulation is required. From this information BS&B will recommend one or more explosion vent application solutions.