Sometimes it’s necessary to cut or weld, or hot work, in the vicinity of your dust collector. However, this can be extremely dangerous if your dust is explosive. A dust collector, after all, is an accumulation of dust, and if that material is combustible, careless hot work could lead to a catastrophic explosion.


“Hot work” is defined by OSHA as “welding, brazing, cutting, soldering, thawing pipes, using heat guns, torch applied roofing and chipping operations, or the use of spark-producing power tools, such as drilling or grinding”. While most of us would think twice about welding or cutting in the vicinity of the dust collector or any other combustible dust, using a spark-producing tool, even one that shouldn’t produce sparks but has faulty wiring, can lead to a fire or explosion.

Person welding

No hot work should be done near the dust collector without the correct procedures (see NFPA 51B). This is the NFPA standard that specifically defines the procedures for conducting hot work anywhere that it might cause an explosion.


Hot work near or on a dust collector might include repairs, adding or removing a piece of equipment or ductwork, or any number of other projects. Before any of this kind of work is done around the dust collector, you must have a hot work procedure IN WRITING:

  • Must be in writing and available to anyone conducting hot work in the area
  • Must specify that an inspection of the work area is required before the work starts
  • Must have a permit signed to show that all phases of the work have been inspected and approved


The program should assess safety equipment in the area. On a dust collector that might include a spark arrestor, spark detector, fire suppression or sprinkler system, abort gate, explosion venting, or other types of fire and explosion safety devices.


Hot work may require completely blocking the ductwork to the dust collector, or if the hot work is on or close to the collector, may require removing the filters, emptying or removing the hoppers, and thoroughly cleaning the entire dirty air side of the dust collector. It is strongly recommended that a fire suppression system be in place before hot work begins to suppress any fires that might start, and that if the dust is explosively combustible, as much of it as possible has to be removed.

CMAXX Dust and Fume Collector on welding application

NFPA 51B specifies that once the area has been inspected and determined to be safe for hot work, the company safety specialist will issue a permit for work to proceed. It’s the job of this designated safety specialist to inspect the area of hazards, make sure that all combustible dust has been removed or isolated from all sparks and heat, and establish safety procedures in the event of a fire.


No one should be allowed to perform ANY type of hot work, including the use of spark-producing power tools, in the vicinity of the dust collector without a permit. However, it happens all the time, and puts lives at risk if the dust is combustible. Take the time to assess this hazard in your own workplace. If the hazard exists, your safety professional should set up hot work procedures to make sure no one puts themselves or the facility at risk.\


Cutting Shelves

Vo-Tech Trade School Student trains at Imperial Systems

Garret Welding on a BRF baghouse

Like many companies in the USA, Imperial Systems wouldn’t exist without our skilled tradespeople. Making a quality product comes from training and experience, and right now we’re lucky enough to have a young man who has come here for both of those things.

Garrett is a student at our local Mercer High School and participates in the Mercer County Career Center Vo-Tech trade school program. Every morning he comes to work at Imperial Systems, welding CMAXX and BRF’s, learning from our experienced team and getting great real-world experience.

Garrett knew about Imperial Systems from a friend who works here in the summer, and he chose us for his Vo-Tech worksite. He told us about how much he’d learned already, and the difference between welding in school and working from blueprints, working on projects that are actually going out to customers and have to be done right. Fortunately, he is eager to learn and enthusiastic about his work.

He’s also enthusiastic about welding in general, as shown by his artwork he created for a trade school skilled trades art show. He got to take his work as far as state competition in Hershey, PA. In school, he plays football, wrestles, and participates in show choir.

Welded Skull Sculpture

While show choir might seem like an unexpected hobby for a welding student, Garrett is an intelligent and well-rounded person, and our conversation ranged from his project on World War II propaganda to the deficit of skilled tradespeople and the over-abundance of college graduates with useless degrees. He has clearly thought a lot about his future and has a good understanding of the need for welders in the workforce and how it has affected his career choices.

He can also tell you from first-hand experience how under-funded trade schools struggle to attract and support students. The demand for skilled tradespeople dwarfs the budget that trade schools have to bring in and train these people. As a result, a future shortage of welders and similar skilled tradespeople looms, and trade schools continue to be neglected as a source of solid, well-paying careers for many young people who don’t see college (or the accompanying debt) in their future.

The school year is almost over, and Garrett has plans for his future in the skilled trades: he has enlisted in the army and plans to work in one of their metalworking divisions. He’s not sure whether he’ll stay in the military as a career, but he knows we have several veterans working here now, so he’d be in good company if he decides to come back.



Clogged ducting

1. What information do we need to start designing a system?

  • First, you need to know about your dust. Important details: how it’s being generated, how toxic or hazardous it is, what exposure levels OSHA considers too high, whether it is combustible and/or explosive, particulate size, physical characteristics.
  • Combustible dust will require special precautions to be worked into the system design to protect the facility and workers from deflagration or explosion. Dust testing can determine how explosive dust is and what precautions are needed.
  • A general layout of the facility and each location where dust is being generated.
  • A sketch of the duct layout, including the location of the dust collector, fans, and duct branches.
  • A plan for the type of hood that will be used at each of the dust capture locations and how much CFM each one will require.

Large Duct run with flex hose drops

2. What are the basic components of a dust collection system?

  • Hoods: must be correctly designed for each type of machine, and must be efficient at removing the dust produced by that machine.
  • Ducts: must be correctly sized to allow proper airflow, keep air moving, and not have too many bends or elbows to slow down airflow; this can allow particulate to drop out of the airflow or can create a point for wear and tear on the ductwork.
  • Fan: the fan must be powerful enough to keep air moving through all the ductwork at a high enough velocity. Drops in velocity or not enough velocity can allow dust to fall out of the air stream.
  • Collector: must be correctly sized for the system, with an air to cloth ratio that makes it able to filter all the air coming into the collector. Must have correct filter material to handle the size and type of particulate (DeltaMAXX nanofiber for most applications, or spunbond, PTFE, or other specialized filters for particular applications). Filters must be fire-retardant if the dust is flammable.
  • Fire Prevention: devices such as spark arrestors can help keep sparks from entering the dust collector. A water or chemical fire suppression system can extinguish sparks or flame when a sensor detects them.
  • Venting/Exhaust: If air is being returned to the building, it must be clean enough to meet all health and safety standards. If dust is toxic, an extra layer of safety in the form of HEPA filters might be needed. A backdraft damper can prevent backdrafts from allowing dust back into the system. An abort gate with spark detector can sense a spark or flame and can divert the flame in a safe direction.


3. What is the process for designing a system?

  • System design should start with identifying each place that a hood or other source capture point needs to go (anywhere that dust is generated).
  • Use appropriate calculations to figure out how much CFM you need at each of these points
  • Determine the minimum duct velocity. This is based on the transport velocity (the air flow needed to keep your particular dust moving in the air stream).
  • Calculate the size of duct for each branch. This is based on the CFM and the transport velocity and will be different for different spots along the ductwork.
  • Increase duct velocity at each branch to maintain transport velocity until all branches are connected to the main duct.

4. Will this be an ambient system or source capture system?

  • Ambient system: removes air from the entire work area, filters it, and recirculates it back into the area, diluting contaminated air with clean air.
  • Air changes per hour: the number of times per hour that the total amount of air in the area is changed from old/contaminated to new/clean. This is calculated by the cubic volume of the work area and the number of air changes required to maintain air quality.
  • Source capture/close capture: captures dust at each point where it is generated throughout the facility.
  • This type of system must have properly designed hoods at every capture point and properly calculated airflow. Specialty hoods can be designed for almost any application.
  • Static pressure in these systems is an algebraic formula that includes loss at hoods, flex ducts, transitions, and straight runs. Minimal use of elbows and flex ducts will greatly improve system efficiency.
  • For dangerous or toxic dust where exposure must be kept to an absolute minimum, a close capture system will keep the material from entering the air of the general workplace.


We hope this set of articles about ductwork help to answer some of your questions. Please thank the knowledgeable and experienced Charlie Miller for providing so much valuable information and sharing his wisdom.


Static Pressure

1.  What do the different types of air pressure measurements mean in ductwork?

  • Basic behavior of air: it always flows through the past of least resistance, from higher pressures to lower pressures.
  • STATIC PRESSURE: potential pressure exerted in all directions in the ductwork with no air flow, measures with a manometer. Can be positive (pressure outward on the duct) or negative (pressure pulling inward on the duct)
  • VELOCITY PRESSURE: pressure necessary to move air through the ductwork at a certain velocity. This is kinetic energy, and the pressure is in the direction of the airflow.
  • TOTAL PRESSURE: a calculation of system static pressure and velocity pressure (the formula is TP=SP+VP). It can be positive or negative. It is the overall energy content of the air stream.


2.  When we calculate our fan size, what’s the difference between SCFM and ACFM?

  • SCFM is Standard Cubic Feet per Minute. This is a measurement based on a standard temperature and air pressure.
  • Temperature and air pressure can be significantly different in different areas (e.g. higher altitude, cold or hot climate, high humidity) or different applications (high/low temperature or humidity applications)
  • ACFM is Actual Cubic Feet per Minute. This is a measurement of the actual air conditions that your system will be operating under.
  • Fan manufacturers are able to make these calculations, but they need to be provided with accurate data about temperature and humidity conditions in your application.


3.  What is conveying velocity and why is it important?

  • Conveying velocity is measured in feet per minute (FPM). It is the velocity required to pick up dust in the air stream and move it through the ductwork.
  • It is calculated by the CFM at the point of capture and the square foot cross-section of the ductwork.
  • This is extremely important because if the conveying velocity drops too low at any point in the dust transport, the dust will drop out of the airflow.
  • There are a variety of tables to help engineers calculate the minimum conveying velocity for different kinds of dust.
  • Combustible materials might need a higher minimum conveying velocity because accumulation of this material in the ductwork could cause a deflagration or dust explosion.


In the agricultural industry, grain dust explosions are a hazard that must be addressed. According to a report from Purdue University, grain dust explosions have occurred at a constant rate over the last ten years, with little change in the number of explosions, injuries, and fatalities. They report an average of 9.3 explosions each year over the past decade.

Since  OSHA instituted Standard 29 CFR in 1988, which specifically details safety in grain handling facilities, there has been a focus on the control of what OSHA refers to as “fugitive grain dust”. Preventing grain dust explosions was a focus, including regulations on any type of “hot work” occurring in the vicinity of grain dust. The standard requires testing for combustible dust presence in all storage containers (silos, tanks, bins). It also requires thorough housekeeping procedures to keep dust from accumulating on surfaces.

Grain dust collection systems are strongly recommended, and they must be designed to resist an explosion or deflagration. Correctly designed systems can prevent an explosion from happening or prevent it from causing damage or injury.

BRF Baghouse on Grain

Purdue University’s report examines the number of grain dust explosions that occur each year. From 1995 to 1998 the number of explosions was high, reaching 18 grain dust explosions in 1998. Numbers stayed below the ten-year average until 2005, with 13 explosions, and then in 2008, with 19 explosions.

The most common months for grain dust explosions, according to the report, are April, August, and September. The report suggests that during these months, there is increased handling and moving of grain.

What’s causing these explosions? Some facilities think that they don’t need to worry about a little accumulated dust as long as there’s no ignition source. As our own Charlie Miller would say, “good luck with that”… in 67.8% of incidents, the ignition source was unknown. Only 6% could be related to fire, with less than 4% related to sparks or mechanical failures. Most of the time, nobody knows what triggered the explosion, which makes it very difficult to prevent an explosion when fugitive dust is present.

The high percentage of unknown ignition sources should be proof that the only prevention for grain dust explosion is to keep fugitive grain dust under control in all parts of the facility at all times. A dust collection system is essential to this, and can include a baghouse, a cartridge collector, or spot filters located at specific grain handling points.

Some other interesting statistics related to combustible dust explosions in the grain industry:

From 2007 to 2016, there were 91 dust explosions, and 52 of those were caused by corn dust. The second most hazardous type was mixed feed, which probably includes corn quite often, with 19 explosions. 20 explosions out of 91 were caused by other types of dust.

In 2017, there were 7 grain dust explosions, slightly below the ten-year average of 9. The locations included a pet food plant, a grain mill, and 5 grain elevators. Grain elevators move large quantities of grain and create a high risk of explosion.

In the last ten years, there have been 101 injuries and 15 fatalities due to grain dust explosions. 55 of the explosions occurred in grain elevators, with feed mills a distant second at 18.

If grain elevators are so hazardous, how can the risk be decreased? Spot filters are often a very good solution for dust control on these facilities. They can be placed almost anywhere that dust is generated and are self-cleaning, requiring only occasional maintenance. They do not require confined space permits to work in and can control fugitive grain at the source.


CMAXX Spot Filter in grain elevator






Imperial Systems Quarterly Newsletter | Issue 5


Imperial Systems Newsletter Issue 5 is the first issue of the year. Make sure to check out all of the articles and interview. If you would like a Printed Hard Copy of this issue of our newsletter please contact your Imperial Sales Rep.


Click Cover To Download and Print Newsletter

Dust Jobs Newsletter Cover Issue 5


Image to link to the Sales Meeting Article

Image link to Good Luck With That "New Beginnings" Article

Image Link to CMAXX breaking into woodworking article

Image link to Interview with Andy King

A Letter from the Sales ManagerImperial Systems has been a family business from the very beginning. Over time, though, our family has grown a lot. We have new employees as well as reps from all across the country who’ve joined our family because they believe in us and our products. Our National Sales Meeting in March showed us just how much our family has grown, and it gave everyone a chance to learn more about our products, while taking a peek behind the curtain to see what we do here and how everything works.

In this issue, you’ll meet some of our new extended family of reps from all over the country, but you’ll also meet Andy, who has been with the company almost since it began and is a long-time member of our close-knit family. As the Sales Manager, a major part of my job is helping our company grow, and it’s been really exciting to have all of these new reps and OEM’s sign on to represent Imperial Systems. Many of them left our competitors and came to work with us, not just because of the quality of our product, but because of who we are.

I’d like to invite anyone who is interested to visit us and see our new facility, get a look at all the great work getting done here, and meet some of the amazing people that make up our Imperial Systems’ family.



A team from Imperial Systems recently spent three days in Denver at the GEAPS (Grain Elevator & Processing Society) annual trade show. GEAPS is “the knowledge resource for the grain industry”. Imperial Systems had a booth at the show to talk about our BRF baghouses, spot filters, and other options for grain industry dust control. Jeremiah and Mitch had a good time at the show, joined by Tommy Eastlack from Glacier Technology, and even got to appreciate some of the Colorado scenery.

Imperial Systems booth at GEAPS

As usual, the show featured many types of equipment used in the grain industry, including elevators, conveyors, screeners, and separators. All of these types of equipment are opportunities for combustible grain dust to become a hazard. Spot filters are an excellent choice for grain dust applications because they can be located anywhere along the process line, including over elevators, conveyors, hoppers, and blenders. Spot filters offer CMAXX efficiency exactly where it’s needed. This is important because grain industry applications often have multiple areas across the facility where dust collection is needed. Spot filters are a solution for controlling those piles of dust that so often form around train moving or mixing equipment.

All of the Booths at GEAPS

When a large collector is needed, a BRF baghouse or a CMAXX may be used, depending on the application. Jeremiah and Mitch took the opportunity at GEAPS to provide information to lots of vendors and potential customers about our products. Fire and explosion prevention and control are also major issues for dust collection in the grain industry, so they also offered information about our products such as abort gates, EIVs, chemical fire suppression, and other options. A representative from Fike was also at the show, highlighting the importance of a strong fire safety program for all grain applications.

During their time in Denver, Jeremiah and Mitch also took the opportunity to visit Table Mountain in Golden, Colorado and the aptly named “Garden of the Gods” park in Colorado Springs. One of the special things about trade shows like GEAPS is getting to visit new places, such as last year’s Fabtech trip to Mexico. Next year GEAPS will be in New Orleans, and we expect that along with a successful trade show, there will also be some extracurricular adventures.



The switch to powder coating is one of the most exciting changes about our move to our new building. With a powder coating booth big enough to accommodate our largest pieces of equipment, we’re prepared to powder coat everything that we produce.

Powder Coating a new BRF Baghouse Dust Collector section.

Why the switch to powder coating? There are so many reasons!

  • Going Green


Powder coating is much healthier for people and the environment. Because liquid paint contains solvents and volatile organic compounds (VOCs), it creates many dangerous emissions that can damage the environment and harm people’s health. Powder coating creates almost no pollution, so it’s a much greener process than solvent-based liquid paints. The EPA considers powder coating a much better option for environmental health.

Brand New Powder Coat Booth with an open sided CMAXX Dust Collector for air-intake and filter.

  • Efficiency


It is extremely efficient. Powder is attracted to and adheres to the metal, and powder that doesn’t stick can be collected and reused. Because there are no VOCs produced, a powder coating booth does not require expensive, complicated air cleaning systems to get all the chemicals out of the air. Powder coating is faster and easier than many other processes. Also, the powder coating process isn’t affected as much by temperature and humidity, meaning that it’s easier for us to get products finished and out the door no matter what the weather is like.


Close up of powder coating process on a BRF Baghouse.

  • Durability


Powder coating produces a durable, tough surface that’s resistant to scratches, chips, and rust. It is used on everything from household items to metal equipment that needs to last many years outdoors in all conditions. It will give our equipment a finish that makes it even more weather-resistant than before, and protect it from rust, scratches, and other damage. We are currently the only company in the USA powder coating a round baghouse, so if you want a collector that’s going to stand up to almost anything, ours is the one to go with.

Our largest BRF Baghouse Dust Collector being loaded into the oven to bake on the Powder Coating.

Our largest BRF Baghouse Dust Collector being loaded into the oven to bake on the Powder Coating.

  • Appearance


If you’re looking for an attractive finish, powder coating is definitely one of the best options. Because it coats evenly and doesn’t streak, run, or smear, it produces a smooth and good-looking finish. Items that are powder coated will look better and have a cleaner-looking surface than items painted with liquid paint. We want the appearance of our products to be as good as the performance, so getting a great finish is the perfect finishing touch.

Freshly Powder coated CMAXX Dust and Fume Collectors ready to be shipped out.

Freshly Powder coated CMAXX Dust and Fume Collectors ready to be shipped out.

The Standard Colors of Imperial Systems

We have made mention many times that we have recently moved into our brand new facility.  One of the major improvements that has been made is we installed one of the largest powder coat booths in the region.  With that we are very excited to be able to powder coat all of our equipment. As a bonus we are the only manufacturer in the United States that can offer a powder coated baghouse. There are 6 color options that are available as a standard and additional colors will be available upon request.  See your sales engineer for additional information on non-standard colors.  Unless otherwise specified all dust collectors are painted with CMAXX Grey.  Any of the stock colors can be used for any of our equipment.

Check out all the options below.

CMAXX Grey Powder Coat Color on a CMAXX Dust Collector

Imperial Blue Powder Coat Color on a CMAXX Dust Collector Header Tank

Safety Yellow Powder Coat Color on an Imperial Systems Abort Gate

Light Industrial Grey Powder Coat Color for a show CMAXX Dust Collector

Patriot Blue powder coat color on a CMAXX Dust Collector

Signal White powder coat color on a large CMAXX Dust Collector

Brand new large Powder coat booth featuring a CMAXX Dust Collector for powder collection


Imperial Systems Quarterly Newsletter | Issue 4

Imperial Systems Newsletter Issue 4 is the last one of the year and the best issue to date. Make sure to check out all of the articles and interview.

Click Cover To Download and Print Newsletter

Imperial Systems Dusty Jobs ISSUE 4



Imperial Systems goes to Fabtech Chicago

Good Luck With That - Smoley and Other Friends

Special Thanks to Our Veterans

Chili Cook-Off 2017

Troubleshooting with Sunflower Seeds

Interview with Steve Higbee



It’s not in my official job title. It’s not what I was hired for. Underneath my ordinary day job in aftermarket sales, I have another responsibility. I am The Editor.

If you read our blog, our brochures, our newsletter, or our published magazine articles, you’ve read my work. It doesn’t have my name on it and I don’t care. Being The Editor has given me a chance to learn  more about our products, our customers, and this industry than I ever would have learned in sales.

Just about every person who works here has a wealth of knowledge and a unique story to tell. Putting those things into written form is what I do. I tap into the incredible resources I have all around me. I ask a lot of questions. Sometimes I get blank stares, and occasionally I get a “why exactly are you asking me this” look with raised eyebrows. But in the end, someone always has an answer.

The best thing about my secret job as The Editor is the pride I feel when our company’s written material sounds professional, when our blog posts are helpful to someone, or when an industry magazine publishes an article. All of this represents the ideas and knowledge of many people; I put it in words and make it sound good.

In a way, that’s how everything works here at Imperial Systems. Everything, from the products we make to the newsletter you’re reading, is the work of a team.