Differential pressure in a dust collector is the difference in air pressure between the dirty and clean air sides of the filters. Most manufacturers recommend that you keep a regular log of the differential pressure measurements. But did you know it might also be required in your air quality operating permit?


Each state issues its own air permits to any business that is going to create any kind of air contaminant. There are different types of permits, depending on the state, the type of pollutant, and the size of the facility. Sometimes businesses are permitted to operate without a permit as long as they comply with certain regulations.




The EPA’s Clean Air Act applies to operations that are major sources of air pollution or particularly dangerous kinds of air pollution. If your company is required to have a Title V Permit, you have very strict regulations to follow, and are required to certify your compliance yearly. If you use baghouses, cartridge collectors, or similar types of particulate collection, a record of differential pressure monitoring is often required.


What if you have a state-issued permit, though? Does it say you have to keep a log of your differential pressure? And what happens if you don’t?


Your state’s air permits may require that companies using baghouses (the EPA and many state agencies refer to all fabric filter particulate collectors as “baghouses”) keep a differential pressure log. Others may not require you to keep a log, but might require that you take certain actions if the differential pressure indicates a problem.


If there is no log of your system’s normal differential pressure changes, you may not know when there’s a change indicating a problem. Unusually high differential pressure might indicate that your filters are being blinded off with dust, and they need to be changed. If the differential pressure is much lower than expected, it could mean you have a leak in your filters or somewhere else in the system.


If you don’t keep any kind of log of what your differential pressure is normally, you won’t have a record to show a state or EPA inspector who comes to renew a permit or to look into a problem. Even if your permit doesn’t specify that you are required to keep a log, it’s good documentation to show that you’ve been diligently monitoring your system function.




Dust collector manufacturers recommend keeping a differential pressure log, regardless of permits or regulations. Monitoring your differential pressure over time will allow you to see when your filters are getting close to needing changed. This lets you order and have replacements on hand, and it’s much more efficient than having to shut down a collector because the filters are so blinded off that they’re not working.


Monitoring can also alert you to other problems, such as leaks in the system that let the air take a shortcut around or through holes in the filters. Any sudden or big changes from your normal differential pressure should be a warning that something might be wrong.


Here’s an example chart from an electronic differential pressure recorder. Every application would have a chart that would look different. For example, the system in this chart only runs for one shift each day and does off-line pulse cleaning during breaks and lunch. You can see the pressure drop after each of these off-line cleanings during the day.


Differential Pressure Monitoring over a day infographic


How you record and monitor the differential pressure depends on your system. It can be monitored by having someone record the number at specified times every day, or by having an electronic monitor that tracks it. Each system’s normal differential pressure graph will look different. The point is to know what your system’s “normal” is so you can tell if anything changes.


If you do have an air permit, it probably contains some statement that you’re responsible for monitoring and maintaining your equipment to prevent air contamination. It might not specifically say that you have to keep a differential pressure record… but keeping that record is a great way to show that you have the monitoring and maintenance bases covered.




A spark trap (also called a spark arrestor) is a critical part of fire prevention in a dust collection system. They help block sparks before they can start a fire. We hope to answer some of your most frequently asked questions about our spark traps here. You can also watch the video below. If you need more information, please feel free to contact us.

  • How do spark traps work?

Our spark traps have impingement plates that cause turbulence and direct sparks and embers toward the walls of the spark trap, which knocks them around and causes them to lose heat. A screen blocks larger debris from passing through.



  • Why do I need a spark trap?

This is one of the most common questions. If there’s a danger that a spark could travel through your ductwork and ignite combustible dust or other materials, a spark trap may be an important part of your fire prevention system. If you need to know whether a spark trap will work for your application, contact us and we’ll help you find out.


  • What size spark trap do I need?

This depends on the size of your ductwork. We manufacture to fit almost all diameters. Our standard sizes are 6 inches to 40 inches but larger ones are available.


  • How do I connect the spark trap to my ductwork?

To make it easy to install, you can choose from three end types. We manufacture them with a raw end, a flanged end, and a quick connect end for clamping. Larger models can be heavy and may need hangers or other support.


  • Where in the ductwork does a spark trap go?

This is another one of the frequently asked questions. They can be installed vertically or horizontally. For proper functioning, the length of duct between the spark source and the spark trap should be at least one duct diameter, and between the spark arrestor and the dust collector should be at least ten times the duct diameter. A shorter distance will prevent the spark trap from working correctly and is not recommended. If you have a question about the length of ductwork, we suggest that you contact us for assistance.


  • What kind of maintenance does a spark trap need?

Our spark trap comes with a drop-down cleanout door that removes easily. This allows you to clean out debris and dust. There are no moving parts that need to be maintained.


  • Can they be used for high temperature applications?

If the temperature of air going through the spark trap will be higher than 200 degrees F, please contact us with details. There are options for higher temperature applications.


  • Does a spark trap work for every application?

There are some applications where spark traps will not be able to function properly. They do not usually work well for applications with wood chips or sawdust, or applications with sticky or fibrous material. We can help you determine whether a spark trap will work in your system.


  • Is your spark trap guaranteed to stop all sparks?

Another one of our most frequently asked questions. No spark trap is guaranteed to stop all sparks. Our design is as effective as a spark trap can be. A spark trap is an important part of a fire prevention system, but it should not be the only part. Our model meets all NFPA standards. We will take the time to help you decide what equipment will best meet your needs.




For any air filter, it’s important to know how efficient it is at filtering out dust and particles from the air. The problem is that not all dust is the same size. This will give you some idea of the different dust size that a dust or fume filter might have to deal with:

Dust size versus the MERV rating of a DeltaMAXX cartridge dust filter



A micron (also called a micrometer) is one millionth of a meter. As shown above, a human hair is about 80-100 microns. A sheet of paper is between 70 and 180 microns thick. Most fibers for use in making clothes are somewhere between 10 and 50 microns.

Here are some other things measured in microns:

BACTERIA – 1 to 10 microns

RED BLOOD CELL – 7 microns

MIST/FOG DROPLET – 10 microns




MERV stands for “minimum efficiency reporting value”. It is determined by testing a filter to find out what dust size it can filter. What’s important isn’t just the dust size, though. It’s also the efficiency: how much of that dust a filter can capture. There are three general categories of dust size used by ANSI/ASHRAE: E1, which is particles from 0.30 to 1 micron, E2, from 1 to 3 microns, and E3, from 3 to 10 microns.

The MERV rating tells you what percent of particles in that size range the filter will capture. Here are some examples:

MERV 6 – between 35 and 50% efficient for dust size bigger than 3 microns

MERV 10 – between 50 and 65% for dust size from 1 to 3 microns

MERV 15 – between 85 and 95% for dust size smaller than 1 micron



Your filter needs to have the right MERV rating for your dust size. For an industrial dust collector, this is especially important for meeting OSHA regulations, keeping your facility clean, and keeping the collector working efficiently.

Metal fume particles and other industrial dust can be smaller than 1 micron. If you look at the chart above, you’ll see just how small that is. It’s much smaller than many other things you can’t even see.

Metal fume and smoke particles can also be dangerous for your health, so it’s important that a filter catches as much of that dust as possible.

DeltaMAXX nanofiber filters have a MERV rating of 15. This means that they will capture between 85 and 95% of particles in the 0.30 to 1 micron range.

If your dust is very hazardous, like hexavalent chromium, you may need to add a HEPA filter. These don’t have a MERV rating: their rating is usually between 99.95% and 99.99%.

So why not use HEPA filters for everything just to make sure? First, they’re expensive. Second, catching that dust size means that the filters have to slow down the air a lot and have a lot of resistance. This isn’t necessarily what you want happening in an industrial air filtration system. For most industrial applications, MERV 15 is efficient enough.


We’ve talked a lot about how the Shadow handles weld fumes and meets the need for a powerful, portable fume collector in weld shops. The Shadow can handle a lot more than just weld smoke, though. Here are some of the applications this versatile source capture collector can handle:


Welding Source Capture with the Shadow



Instead of a fume arm, the Shadow can easily have a hose that attaches to other metalworking equipment, such as a cutting table. In a bigger shop, a cutting table might have its own fume collector. If your shop is smaller or the cutting table doesn’t get used all the time, the Shadow might be a great solution. You could hook it up to the cutting table, then easily roll it to the welding area, put the fume arm back on, and use it there.



Do you do grinding work that gets dust all over your shop, but not enough to need a full-sized dust collector for it? The Shadow’s source capture arm doesn’t just have to go over a welder. It can also go over any other dust-producing work area, like grinding or sanding. The collector takes up minimal floor space, and when you’re not using it, it’s easy to roll it out of the way.



In a woodworking shop, you might have dust being produced at a lot of different places, depending what you’re working on. One big dust collector could handle it all, but maybe your shop doesn’t need something that big, or maybe you just need something to handle one spot that’s extra dusty. The Shadow can move around your shop to wherever you need it, and the source capture arm adjusts to go exactly where you need it.



OSHA’s new silica laws are very strict about controlling exposure to silica dust. If you have stone cutting or grinding going on, the Shadow can be moved wherever it’s needed for source capture of silica dust. Not all portable collectors are built strong enough to handle abrasive particles like this, but the Shadow is designed to work on almost any type of dust. It can go from stone cutting to woodworking to a cutting table, and it can do it as often as you need it to.



If you’re collecting metal fumes, wood dust, or other combustible materials, a plastic collector could have a serious problem. If a fire occurs, a plastic collector could end up as a charred, melted lump, but the Shadow’s sturdy metal design will still be standing strong. If you’re going to be rolling a collector all over your shop, a cheap design that can’t handle the stress isn’t the best value. The Shadow’s nanofiber filter works with everything from wood dust to weld fumes and pulses clean for low maintenance and high efficiency.




From May 2nd to May 4th, you’ll find Imperial Systems President/CEO Jeremiah Wann and Sales and Marketing Manager Justin Badger representing the company at FABTECH Mexico. Travelling to Monterrey, they’ll be bringing along a CMAXX dust and fume collector to introduce it to our growing international market.

“We’ve sold equipment to places in Mexico and Central America in the last few years,” says Jeremiah Wann. “We want to keep growing our presence there.”

CMAXX on display at Fabtech

FABTECH Mexico isn’t just an opportunity to give a new market a chance to see the CMAXX dust and fume collector. It’s also an opportunity for Imperial Systems to seek out new representatives of our products in the area.

“We have representatives all over the United States,” Jeremiah says. “We’re ready to find some dust and fume collection professionals who are ready to represent our products in Mexico and Central America.”

Many manufacturers in Mexico are upgrading their dust collection systems to provide better air quality for employees. Also, many international brands with manufacturing facilities in this area expect these facilities to meet the company’s overall health and safety standards.

Imperial Systems is ready to step into this market with the CMAXX, BRF baghouse, and other equipment to help these companies meet all of their air quality control needs. Bringing new representatives to work with us will help us expand into these areas.

FABTECH Mexico is a great chance to take the CMAXX to places it’s never been before. Keep an eye on our Facebook page for lots of photos as Justin and Jeremiah document their adventures! Like all our trade show experiences, we expect them to come back with lots of good leads and a few good stories.


A portable fume extractor is a great solution for welding and metalworking applications that need a mobile, flexible option for fume collection. There are many portable collectors on the market, from low-end plastic models to ones made for serious industrial use.

Deciding how much to invest in a portable fume extractor depends on how well you need it to hold up to what you’re using it for. The fumes and smoke from welding or metalworking applications can be very demanding on a collector, and a cheaper model may not be able to handle the job.

Shadow portable fume extractor removing welding fumes

Metal fumes are a health hazard when inhaled, and a portable fume extractor with a fume arm can be a great solution for pulling those fumes right out of the welder’s breathing space.

However, the fume extractor has to be powerful enough to remove the fumes. It also has to have a filter that can handle particles that small without letting them get back into the shop. It needs to have a high-quality arm that is easy for the welder to move around and work with.

The Shadow is a portable fume extractor designed for industrial use. Its sturdy metal design minimizes its floor space, and heavy duty casters mean it rolls easily to wherever it’s needed. The DeltaMAXX nanofiber filter is MERV 15 to handle welding smoke and fumes, and with compressed air pulse cleaning, it will maintain its efficiency much longer.

Another area where low-budget portable fume extractors can let you down is the fume arm itself. The Shadow’s fume arm options make it easy to choose the one that will work for your application. The Shadow arm’s hood is sized to maximize fume capture while not getting in the welder’s way.

Shadow Portable fume collector arm

Joints are needed to move a fume arm around and hold it in position. When these joints are inside the arm, they collect debris and obstruct the airflow. External joint components are easier to access, and they don’t interfere with your airflow.

For our customers currently using the Shadow for welding applications, it’s doing everything they need it to do. Customers have told us that as a portable fume extractor, the Shadow is efficient, does a great job of keeping the air clean, and is easy to use. Welders appreciate the well-designed arm and hood that is easy to position. The nanofiber filter is very easy to keep clean with compressed air pulsing and it’s very easy to access for filter changes.


When you’re choosing a cartridge dust filters for your dust collector, there are several factors to consider. You’re obviously considering price. You probably know, though, that cheaper is not always better. Filters that don’t last and don’t perform well aren’t a bargain no matter how cheap they are. We’ve worked with companies who ran into exactly that problem, and they found our DeltaMAXX nanofiber filters to be a great solution.

DeltaMAXX replacement cartridge dust filters

APPLICATION: Community College Welding Program

PROBLEM: Very tight budget, fume leaks

SOLUTION: As a community college, this customer didn’t have much money to spend on cartridge dust filters for their weld fume collector. They had tried other filters in the past, but they weren’t lasting as long as they needed them to. Also, they had issues with poorly made, cheap filters letting fumes blow back out of the collector.

After installing DeltaMAXX nanofiber filters, they were very satisfied with the results. They have experienced no issues with the filters letting fumes escape. And to ease the budget crunch, the new filters are lasting much longer than their previous ones, saving them money.


APPLICATION: Lead Products

PROBLEM: Filters overheating and falling apart

SOLUTION: Lead dust is a tough application for any filter, and because lead is so toxic there’s no room for cheap filters that fail. That’s exactly what was happening to this company, though. Within months of purchasing their cartridge dust filters from the manufacturer, they were overheating and falling apart, with the inner metal grate melting and chunks of filter media falling off the filters.

The customer started using DeltaMAXX filters, and found that they were much better quality than the previous ones. They last much longer, have none of the problems with overheating or falling apart, and as a bonus they are cheaper than the original ones. Since lead dust is such a demanding application, DeltaMAXX nanofiber’s very high efficiency (MERV 15) makes sure that air quality compliance isn’t an issue.

DeltaMAXX cartridge dust filters with overbags

APPLICATION: Blasting and Polishing

PROBLEM: Very high dust volume, filter failure

SOLUTION: Running blasting equipment sixteen hours a day takes a toll on dust collector filters. This customer was changing their cartridge dust filters at least three times a year. That meant that at least three times a year all the blasting equipment had to be down while filters got changed, hurting production.

Since purchasing DeltaMAXX nanofiber filters, the company has reduced filter changes (and associated down time) to less than once a year. The customer is very pleased with the improvement, and also with the significant cost savings. Not only do the filters hold up to the abuse of 16 hour days, but they do it for up to four times as long.


APPLICATION: Powder Coating

PROBLEM: Static Buildup and Sparking

SOLUTION: This small business owner knew he had a major safety issue when static buildup inside his dust collector started to ignite powder inside the collector. Grounding the collector didn’t solve the problem, but Imperial Systems was able to step in with specialized filters that did the job.

A specially coated spunbond DeltaMAXX filter with a ground wire eliminated the issue of static buildup in the collector. With cartridge dust filters designed for even very specific applications, we could step in and offer the customer exactly what he needed. He’s very satisfied and confident that his employees and his shop are now safe from dust fires.

Cartridge dust filters are used in as many different applications as you can imagine. There’s one thing they all have in common, though: the filters have to be efficient, long-lasting, and fit in the budget. No company wants to waste money on failing filters, excessive down time from changing filters all the time, or paying higher prices. DeltaMAXX filters offer many companies a solution to all of these problems. Find out what others in your industry already know and talk to your Imperial Systems customer service person today.



The baghouse is a workhorse of the dust collection industry, handling everything from high temperatures to rough, abrasive dust. The Imperial Systems engineers are experts in designing baghouse systems specifically for woodworking and paper recycling applications. The BRF baghouse has proven itself in these industries, as these case studies show.

BRF Baghouse for Wood applications




This woodworking company had installed a dust collection system, but within just a week their filters were already blinding off. After spending a lot of money on over-bags, constant compressed air pulsing, and filter changes, they needed to make a change.

Not all collectors are suitable for all applications. The Imperial Systems team examined the problems the company was having, and it was decided that a BRF baghouse was the right solution. The problem was a very fibrous wood dust. The original collector was a cartridge system, and cartridges usually aren’t the best solution for fibrous or stringy material.

Because each BRF baghouse system is designed for each customer’s needs, we applied our knowledge of woodworking applications to solve this customer’s problem.

With the BRF handling their fibrous wood dust with no problems, the company has cut down on compressed air use, filter changes, and production downtime. Because Imperial Systems makes cartridge collectors and baghouses, we’re able to determine which one will work better for a particular application.



BRF Baghouse for Paper application




This paper recycling company runs 24 hours a day, 365 days a year. The dust load is heavy and constant. The systems they had in place were not up to the job: several inches of dust had accumulated on surfaces around the facility, creating a very severe fire hazard. Also, there was so much dust in the air that employees had to wear dust masks, and they were dealing with respiratory infections and eye irritation.

With employees’ health at risk and a combustible dust accident waiting to happen, the company came to Imperial Systems to see if we could design a solution to handle their very heavy dust load.

From consultation and drawings to engineering and fabrication, the company had constant contact with the Imperial Systems team, making sure everything would work exactly as they needed it to. The project was completed in March of 2014, and the company had great praise for the design and installation teams.

Since installing the BRF baghouse for paper dust, the company is now fully NFPA compliant and dust accumulation is no longer a problem. The facility is clean and the health problems the employees had been dealing with are resolved.

Not just any system can handle a heavy dust load with round-the-clock shifts. Imperial Systems has the experience in the paper recycling industry to design a system that will handle this kind of abuse for many years to come.


Installing a robotic weld cell collector above a robotic welder might seem like a great idea. All the fumes produced by the robot are quickly removed. The collector doesn’t take up any space on your crowded shop floor. What could possibly be wrong with this setup?


A robotic welder is an expensive piece of equipment. It’s a big investment for any company. So the last thing you’d want to do is put it near anything that might damage it, right?


How about putting it right underneath something that might damage it?


Installing a weld fume collector above a robotic welder does save floor space. Since they’re mounted above the welder, they are completely out of the way. There are some hazards with this arrangement, though, and we’ve seen them in action.


Weld fumes are almost always combustible. If the fume collector is located at some distance from the robotic welder, a deflagration that happens inside the collector will not damage the robot and will be contained in the collector. On the other hand, if you have a robotic weld cell collector mounted directly overhead, the deflagration is going to happen right above your very expensive piece of equipment.


A properly designed dust collection system will handle and safely vent an explosion. If the collector is outside the building, there will be minimal risk to people or property. The length of ductwork between the welder and the fume collector gives hot air and sparks time to cool down before they reach the collector.


When robotic weld cell collectors are in use, they’re inside the building and mounted overhead. There is almost no space between the source of fumes and the collector. This greatly increases the risk of a deflagration inside the collector.


This could be a disaster for your robotic welder. Burning material or debris could fall on it and damage it. A fire suppression system could shower your welder with water or fire extinguishing chemicals. Your robot welder could be taken out of service for costly repairs, or it could even be destroyed.


The floor space saved by mounting a robotic weld cell collector above the welder isn’t worth the cost of repairing or replacing a robotic welder. A dust and fume collector system with hoods can effectively control fumes from the welder without the risk of damaging it.




No secret here that we love vertical dust collectors. They’re better than horizontal collectors in just about every way, which we discussed in our last post. Not all vertical dust collectors are created equal, however. Today, we’d like to share a customer’s experience with a competitor’s vertical dust collectors and why he’s choosing a CMAXX this time.

A manufacturing company approached us recently, looking to replace their current vertical cartridge collector. In the time since they purchased it, they’ve experienced many of the problems that we often see with other brands of dust collector. They even sent us pictures to show us what they were dealing with.

Rusted vertical dust collectorsRust is a major factor for any piece of metal equipment that’s going to be outside, exposed to the elements, for many years.  Most vertical dust collectors manufactured by competitors such as Camfil Farr and others are bolted together from the outside. Every external bolt hole is an opportunity for rust. In the photos, it’s easy to see where the bolt holes have rusted and allowed rust to form all over the collector.

The customer told us that they prefer the CMAXX design specifically because of experiencing this problem with their current collector. There are no external bolt holes on the CMAXX, so this is one problem they won’t have to worry about.

FARR Dust Collector rusted bolts

Another problem the customer has experienced with their current vertical dust collector is the roof: they have had to repaint it three times just to keep it from rusting through completely. This is a major issue, because a hole in the roof would allow the cartridges to get wet and be ruined. The customer has had serious concerns about the roof of this collector for years and has been struggling to keep the rust problem under control.

The customer liked the domed CrownTech roof of the CMAXX, which allows snow, water, and debris to slide off the roof instead of sitting on top. Unlike any of our competitors in the vertical dust collector market, the CMAXX is specifically designed to solve the problem of rusting on the collector roof. On a Camfil Farr or any other brand of vertical dust collector, everything that falls onto the roof sits on the roof. Over time, this causes the roof to rust and fail.

FARR Rusted Bolts and Rusted Roof

When you choose a dust collector, you’re making a major investment. Like our customer, you’re expecting this purchase to last for many years. You know you’ll have to replace filters. You’re expecting that certain parts, like valves, may need maintenance occasionally. This is typical maintenance you’ll perform on any vertical cartridge collector, whether it’s a CMAXX, Camfil Farr, or any other brand. However, repairing holes in a rusting roof isn’t something you probably planned to do, and with the CMAXX design you won’t have to.

Our customer sent us these photographs of their current collector to show us the concerns they had with it, especially the issue of rust on the roof and around external bolts. They are switching to CMAXX because it’s designed not to have these problems. With no external bolt holes and a domed roof to protect it from the weather, their new collector will give them many years of rust-free service.