When protecting vessels from explosions, one of the most common ways is to install explosion vents as part of an industrial dust collection system. The explosion vent is an engineered weak spot in the vessel that fails when the internal pressure reaches a certain point. This failure allows the pressure to be released in a controlled way so that the entire vessel doesn’t explode. The explosion vent needs to be installed so that the venting is away from any equipment, walkways, roads, picnic areas, etc.

Explosion vents are primarily used when the vessels are located outdoors, however they can be used indoors, if certain criteria is met. To install an explosion vent indoors, the vessel has to be located by an exterior wall. The vent would then be ducted through the wall, so in case of an explosion it is directed outdoors. An indoor explosion vent will usually need to be larger than an outdoor explosion vent. This is due to additional combustion of material in the duct and the inertia of the air mass in the ductwork. Proper explosion vent design plays an important role in industrial dust control and overall system safety.

The following is an explanation taken from FM Global 7- 76 Section 3.1.8

During the early part of the venting process, unburned dust is ejected into the duct ahead of the flame front from the vessel. When the flame front moves into the duct, dust starts to burn within the duct and generate additional combustion products. Those combustion products expand in ALL directions, thus slowing down or even reversing the flow out of the vessel and the pressure builds up within the vessel.

Inertia of the air within the duct also increases explosion pressure within the protected vessel. When the explosion vent opens and combustion gases first start flowing into the duct, those gases must push all the air out of the duct. During the time required to eject the air, the pressure continues to grow within the vessel because the combustion gases are obstructed from reaching the open atmosphere. In a long duct, that mass of air can delay the venting of the combustion gases enough to significantly increase the pressure in the vessel. These factors should be considered when designing or performing a dust system evaluation for facilities with explosion protection requirements.

So if you’re installing a vessel indoors and you want to vent it outside, keep it as close to the outside wall as possible.

To improve efficiency and safety, there is no substitute for an on-site inspection by an experienced expert. Click here to speak with a member of our engineering team about your application, anytime. 

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Need to implement a cyclone dust collector into an already compliant dust collection system? What does it take to keep everything compliant with the new addition?

Not only do NFPA compliance regulations require a DHA (Dust Hazard Analysis) to be done on all systems that might have explosive dust, they also require the DHA to be updated every 5 years and whenever the system changes. 

Simple Changes in Documentation

Changes might involve adding , removing,  or changing equipment or changes in the material going through the system. 

Since a DHA has already been done, the scope of the change is much less.  Using the information in the original DHA, the equipment that is being changed can be analyzed to make sure it complies with NFPA.  This report will then be added to the existing DHA so that a record of change is documented.  Usually the report is considered a mini-DHA or System DHA. 

The mini-DHA or System DHA often can be conducted by a 3^rd party consultant working with the equipment manufacturer.  This usually can be done without a site visit.  Aerodyne offers the Mini-DHA/ System DHA for our cyclone separators.

There is no substitute for an on-site inspection by an experienced expert. Click here to talk to an engineer about your application. 

Space Constraints in New Facility

In new facilities, the installation of dust collectors is often pretty easy.  Many times the building is designed around the equipment.  This doesn’t mean that compact equipment isn’t beneficial.    This can help lower ceilings, prevent the need for installation on the roof.  When placing a dust collector in new facilities, it would best to place them as near to the system as you can while conforming to all the NFPA and other specs.

Space Constraints in Existing Facility

Existing facilities pose much more issues than new facilities.  Often times existing facilities are constrained for space.  They have added / expanded lines in a building that weren’t built for its current use.  New regulations could require a new dust collector, larger dust collector, or modification to the dust collector (including explosion protection).  All of this could require finding room for a new dust collector or moving the existing one.

Noises from Dust Collector and Fan

If the dust collector is not going to be mounted indoors, it needs to fit under the existing ceiling.  Low profile units are often required.  It might be easier to use low profile point of use dust collectors than to find a place to install a large dust collector for multiple processes.  It is often beneficial to locate the dust collector as close to the processes it is collecting dust from.  This lowers the cost of the system by minimizing ductwork which in turn minimizes the fan size and HP.  When installing the dust collector you should remember to take into account noise from the dust collector and the fan.  Fan silencers and noise blankets may be required if the equipment is too loud.  And as discussed above, enough space should be available for installing all the explosion protection required.

Protect Dust Collection Equipment from Weather

If the dust collector is not going to be mounted indoors, height is usually not an issue.  Some facilities do have outdoor height restrictions.  Sometimes it’s the local city and sometimes it is to keep a low profile with the neighbors.  The dust collection equipment must also be protected from the local weather.  Equipment in the Midwest often requires freeze protection, while the Gulf Coast need to withstand high winds.  When locating the dust collector outside you should install it as close as possible to the process, so as to minimize ductwork and power requirement.

Conform with NFPA

Many customers when installing equipment have to deal with local ordinances on the appearances of the outside of the facility.  Other times, the company wants the facility to be aesthetically pleasing, and / or they want their neighbors to be comfortable with the appearances so as to minimize any issues in the future.  And as mentioned before, the dust collector should conform with NFPA when installed on an explosive application.

To learn more about compact dust collector, please contact our experts at 440-543-7400 or through here.

OSHA is issuing citations and fines to companies with unsafe combustible dust hazards, using their general duty clause and NFPA 652: Standard on the Fundamentals of Combustible Dust as a guideline. Any industrial facility that creates dusts or uses powders was mandated by NFPA 652 to complete a Dust Hazard Analysis by September, 2020 to identify the presence of combustible dusts and establish a plan for eliminating or mitigating potential risks associated with these dusts in their facilities. The DHA is essentially the framework around which NFPA 652 is built, and the starting point for getting a facility into compliance with the standard as a whole.

Dust Hazard Analysis (DHA) Complexity

The complexity of performing a DHA varies with the complexity of the facilities and processes being analyzed.  For instance, a small wood cabinet making shop with a limited number of dust generating machines will present a less daunting task than a large scale manufacturing facility that use powdered raw materials and performs cutting and grinding of its finished product. It should also be noted that performing a DHA should not be viewed as a “one and done” procedure that is completed and forgotten. As new processes or raw materials that have the potential for impacting a facility’s combustible dust profile are introduced in the facility, the DHA needs to be modified to incorporate these changes accordingly.

Dust Hazard Analysis (DHA) Preparation

Preparation for a Dust Hazard Analysis can also be incorporated into a more comprehensive review of a facility’s dust collection system that examines overall system design, efficiency, and safety. Aerodyne Environmental’s Dust Efficiency Clinic offers dust collection system evaluation services that do just that. An Aerodyne dust collection specialist will review a facility’s equipment, installation, controls, and protective devices with an eye toward improving overall system performance, decreasing maintenance costs, prolonging equipment life, and improving safety and regulatory compliance.

Dust Hazard Analysis (DHA) Report

At the end of the system review, a report is generated that summarizes the existing state of the dust collection system and offers targeted suggestions for areas that can be improved. This valuable service offers facility and plant managers outside expertise in boosting the performance and safety of their systems, and is a logical first step in preparation for a DHA.

To learn more about Aerodyne’s Dust Efficiency Clinic consulting services, call Dan Navicky at (440) 543-7400 or tollfree at (800) 358-7546, or email dc@dustcollectorhq.com.

1. Health and safety
   • Dust can cause health issues, even if the material isn’t a carcinogen or sub-micron. Dusty air can cause issues breathing, allergies, etc.  All of this can cause operators to be sick more often or want a new job.  This can cause increased operating expenses and less efficiency as you have to cover for absences or have to train a replacement.   Small local dust collectors can help clean the air around operators.
   • Some dust is explosive, and the regulatory agencies are requiring that you test the dust to make sure it isn’t. Even if they haven’t gotten around to it yet, a fire or explosion will cause property damage and possibly injury to employees.
2. Maintenance – Dust will get into mechanical equipment and cause increased wear on them. This increases the maintenance on the equipment, lower productivity and increase operational expenses.  Installing a local dust collector can minimize the dust getting to the surrounding equipment, thereby extending their life.  While there are many factors that affect when equipment needs maintenance, minimizing dust in the air will definitely help extend the time between maintenance.
3. Recycling of material – Local dust collection can help capture product / raw material dust before it is contaminated by other material. This dust can then be reused or recycled, thereby lowering the cost of your process.  Cyclonic dust collectors are especially good at collecting un-contaminated material since they have no filters to retain dusts and can be cleaned out.
4. Environmental responsibility – Local dust collection will help you keep fugitive dust from escaping the building and into the environment. While rain and wind often deposit dust back on the ground, the more dust escaping will cause the air to be dirtier. This could cause smell or dust clouds that neighbors will dislike.  Beyond being a good direct neighbor, you may just have a goal to be a better inhabitant on the earth.
5. Higher morale – A cleaner, healthier environment will help your employees be happier at work. If they aren’t irritated from dusty air, there is a better chance they will enjoy work better and be more productive.  This will allow you to produce more at a lower cost.  And the company will make more money allowing the employees to get better raises.

To learn more about which dust collector, please contact our experts at 440-543-7400 or through here.

The Benefits of Clamp Together Ductwork 

• Easy to design – One of the main benefits of clamped ductwork is that extremely accurate measurements aren’t required. The clamp together ductwork allows you to adjust the length.  This makes installation of the ductwork much easier than standard flanged ductwork.  So when you are designing your ductwork, you just sketch the ductwork out.  From the sketch you figure out the pieces that you require and then order them from your preferred supplier.
• Easy to transport – Clamp together ductwork is also easier to transport, as the ductwork usually comes in 5 foot sections.
• Easy to install – When it comes time to install the ductwork, all you need to do is begin installing it and trim any pieces that are too long.
• Ideal for mobile systems – Portable applications that require frequent disassembly and re-assembly.

The Restrictions of Clamp Together Ductwork

One thing to be aware of is that clamp together ductwork cannot be used as the ductwork between a dust collector and the no-return/ isolation valve.  NFPA specifications require that the ductwork be flanged together and strong enough to prevent a breach in case of an explosion.  This means when you are designing and installing the system, this ductwork needs to be ordered as flanged ductwork.  The no-return / isolation valve will have specifications on the distance it needs to be from the dust collector.  They may also have guidelines on elbows etc.  Most clamp together ductwork suppliers offer flanged ductwork too.  So you just need to order the required flanged ductwork when you are ordering the rest of your ductwork.

To learn more about the right dust collection solution for your application, please contact our experts at 440-543-7400 or click here to download our Dust Collection System Evaluation Guide.

Using Spark Arrestors to Prevent Filter Fires

Any well-thought-out system will consider this scenario and incorporate preventive measures to reduce the likelihood of filter fires. Installing a spark arrestor in the ductwork before the baghouse is a method that is commonly used to reduce fire risk. Spark arrestors vary in design, but most of them are designed with the intent of slowing the spark down, allowing it to cool down and burn out before it can do any damage to the baghouse or cartridge collector.

Another option is incorporating a pre-filter cyclone before the fabric filters. A cyclone works on the same principle when it comes to spark arresting, using centrifugal force to direct any sparks to the cylindrical surface of the cyclone, spinning them along the metal walls of the cyclone where they are drained of their energy via conduction. The cyclone has the added benefit of removing the majority of heavier particulate before it reaches the filters, which alleviates overall system loading.

The ongoing emphasis by OSHA and NFPA on combustible dusts and dust collection systems in general means that regulatory compliance will become increasingly important for any facility that uses dust collectors.  Prevention and suppression devices such as sprinklers in the ductwork, explosion vents, chemical suppression systems, and cyclone pre-filters can all be used to reduce and possibly eliminate the risk of filter fires. The type of dust being collected, the combustibility of the dust, dust particle size, and filter construction are among the factors that must be considered when selecting the appropriate fire protection for your system.

Which prevention or suppression system does your dust collection system need? Asking that question is the first step in protecting your system, your facility, and the people who work in your facility.

To learn more about how Aerodyne can help you keep your dust collection filter cleaning system operating efficiently,  please contact our experts at 440-543-7400.

1. Deflagration isolation by flame quenching (close-clearance valves) or
2. Deflagration isolation by material blocking (product layer above the valve)

Most rotary valves use flame quenching to achieve compliance with the spec.  Basically this requires the valve to have a clearance to the housing no greater than 0.2 mm and have at least six vanes, so that two vanes are isolating the event at all times.

Many rotary valves manufacturers comply with these specifications.  When you are looking at a rotary valve for you combustible dust application, remember to confirm that the valve complies with NFPA-69.

If you are having operational issues on your dust collection system, contact Aerodyne at 440-543-7400 or dc@dustcollectorhq.com.  He is available to help you problem solve your dust collection issues.