Dust Collector System with Ductwork

The first stage of the dust collection system are the collection hoods. Well-designed hoods are engineered so the dust generated by the equipment can be collected with the least amount of airflow possible. Once the dust leaves the pickup hoods, it travels through ductwork until it reaches the dust collector(s). In a well-designed dust collector system, the ductwork will be sized so that the airflow has enough velocity to keep the dust from falling out in the ductwork. Usually, the airflow needs to be between 4000 and 5500 FPM to keep dust from falling out. So, if the airflow in the system changes from its designed conditions the velocity in the ductwork will also change.

When The Airflow Is Too High

With too high of an airflow, the air velocity in the ductwork will increase. This will cause increased pressure drop in the system but it will also increase the erosion of the ductwork walls by particles making contact with the walls. Increased erosion of the duct walls will cause holes to develop, which will further affect the airflow in the system

When The Airflow Is Too Low

With too low of an airflow, the air velocity in the ductwork will decrease and could allow dust to begin dropping out and building up within the ductwork. This can cause the ductwork to become heavy and fall. If the dust is explosive, this dust can cause or feed an explosion and is a safety risk. If enough dust piles up, it could end up plugging the ductwork, thereby cutting off airflow through the ductwork.

To improve efficiency and safety, there is no substitute for an on-site inspection by an experienced expert. Click below to start with a free 20-minute phone consultation by clicking the button.

We all know that if we don’t regularly maintain our cars, we will end up having issues in the future. If we forget to change the oil, change the brakes or get a tune up, it will eventually catch up to us. Why do we think our dust collection system is any different? Dust collectors are made of various pieces, all of which have to be operating correctly for the system to operate as desired. Usually, a dust collection system consists of the dust collector, exhaust fan, ductwork, and hoods/pickup points. Additional accessories such as airlocks, controls, instrumentation, and dampers all can affect the operation of the system.

The following questions with quick explanations will help you evaluate your dust collector. If after going through this guide you think your dust collector needs a tune-up, contact a local expert or Aerodyne Environmental and have them come in to help you get your system working properly.

Pickup Points

1. Are the areas near the pickup points dusty? Is there any dust in the air, is it hazy, or is breathing in the area a bit difficult?

2. Are there dust piles around the area? Dust piles and layers of dust can become airborne and if the dust is explosive, it can lead to an explosion causing significant damage and injury.

3. Can you feel airflow being pulled into the hood or pickup point?Often times, dust collection systems will be modified and this could cause a loss of airflow at other areas in the system.

4. Did the dust collection system ever work as expected? Sometimes a dust collection system has never fulfilled expectations. This doesn’t mean that changes can’t be made to get it working better.

Ductwork

1. Does the ductwork have holes? Holes allow air to leak into the system, this will cause less air to be picked up at your hoods and pickup points.

2. Are you plugging up your ductwork? Plugged up ductwork is caused by low air velocities through the ductwork. This will cause low airflow at your hoods and is an explosion danger.

3. Have you added or de-commissioned pickup points on your system? Adding or removing pickup points can cause the system to be out of balance. If you have done this without re-evaluating the whole system, your system may not be operating correctly.

Dust Collector

There are a variety of different dust collectors available—baghouse and cartridge collectors, cyclones, and wet scrubbers. Each one of them has different things to look at. We will only address a few of them here. Contacting a dust collection expert such as Aerodyne Environmental can help you diagnose issues.

Baghouse and Cartridge Collectors

1. When was the last time you changed filters? Some customers have to change filters twice a year, others haven’t changed them since they were installed. Both examples could have issues.

2. What is the pressure drop across your filters? Pressure drops over 6” W.C. usually tells you that you need new filters soon. A low pressure drop can mean that you have holes in your filters or haven’t properly developed a dust cake on the filter.

3. When was the last time you did a maintenance check on your dust collector? If you haven’t done it in the past year or two, it might be time. Filters, tube sheets, diffusers, air valves, manifolds and a variety of other items can all develop issues.

Cyclone

1. Have you checked your cyclone for holes? Cyclones often wear faster than other dust collectors, so a yearly check for pin holes or wearing is always a good idea.

2. Do you have a filter after your cyclone? Since cyclones have lower removal efficiencies than most other dust collectors, if your cyclone doesn’t have a filter afterward, you might want to monitor the emissions regularly to make sure you’re not emitting too much dust.

Wet Scrubbers

1. What is the pressure drop through the wet scrubber? Higher than normal or lower than normal pressure drops always tell you something is happening. Higher pressure drops usually means that dust is building up in the system. Lower pressure drop usually means that less airflow is going through the system.

2. Do you monitor your water usage and the particulate loading of the overflow? The overflow stream of the wet scrubber removes the particulate and the dissolved solids from the system.

3. Are you taxing your water treatment plant? Water treatment is expensive so if you can lower the amount of water going to it, you could save money.

Exhaust Fan

The exhaust fan usually provides all the motive force in a dust collection system; therefore, if the fan isn’t working properly the whole system will be having issues.

1. Is the fan vibrating excessively?
2. Is the fan making more noise than usual?
3. Are the bearings in the fan running hot?

Excessive vibrating and unusual noises can mean that something is wrong with the fan. Damage to the impeller or dust build up on the impeller could cause this. Some fans do get unbalanced over time and could cause the fan to stop working. A bearing running hot could be caused by an issue with the fan or an issue with the bearing. Hot bearings, while unlikely, have been known to cause fires or explosions if all the conditions are right.

Miscellaneous

Other items to check on your dust collection system include dampers, airlocks, controllers and instrumentation. Dampers not operating correctly, or accidently opened/closed can cause operating issues. Airlocks under dust collectors can cause air leakage into the system or prevent dust from leaving the system. Controllers and instrumentation can cause the system to shut down, or provide wrong reading, thereby affecting the operation of the system.

To learn more about which dust collector, please contact our experts at 440-543-7400 or visit our website: www.dustcollectorhq.com.

To improve efficiency and safety, there is no substitute for an on-site inspection by an experienced expert. Click below to start with a free 20-minute phone consultation by clicking the button.

When you are designing your ductwork, there are two ways you can do it. 1) You can use dampers to control the airflow at each pickup and balance the system or 2) You can balance by design which means the ductwork is designed so that the proper airflow goes through each pickup without the need to install dampers. There are positives and negatives with both. The following will go over them.

Balance by Dampers

Using dampers to balance your system provides much more flexibility but is much harder to achieve. This design has dampers at each pickup point which allows you to dial in the design airflow. It will allow you to add and remove pickup point (within reason). Of course, the duct needs to be designed so the minimum air velocity is maintained to keep any dust in suspension.   The major issue with using dampers is that you have to balance the whole system, and every change affects every other damper. This means it takes skill and a lot of patience to balance the system. And any change, whether it is adding or removing a pickup point, the accidental (or deliberate) adjustment of the damper will affect the rest of the system. This could mean a total rebalancing of the whole system.

Basically, what this means is that if you require a versatile system which allows you to bring areas online or take offline while keeping the system as small as possible then using dampers is best for you. Just remember that every time you change the damper location you will need to rebalance the system. If you are not experienced this can be a very frustrating and time consuming job.

Balance by Design

The balance by design ductwork is designed so that the resistance throughout the system is such that the correct amount of air is being picked up at each pickup point. This has a few benefits, the first being it is an install and forget design. (Please note we don’t actually mean forget). Once the ductwork is designed and installed, it will naturally pick up the designed amount of air until something changes. A properly designed system will have enough air velocity in each area to keep dust from falling out. So this means you won’t need to adjust anything. We would recommend periodic checking of airflows to be sure the system is operating at the right airflow. If you find that it isn’t then the ductwork has been damaged, changed, or material has built up in it.

The negative of this design is that once it is installed you can’t change it easily. If you are adding or removing any pickup points then you may need to modify the ductwork to be sure you keep the design airflows. You will have to pay special attention that your airflow remains high enough to keep any dust in suspension. The other negative is that it will pull the airflow from all pickup points all the time. And if you are looking to use only one pickup point at a time, then the system will be bigger than might otherwise be needed.

To learn more about which dust collector, please contact our experts at 440-543-7400 or visit our website: www.dustcollectorhq.com.

To improve efficiency and safety, there is no substitute for an on-site inspection by an experienced expert. Click below to start with a free 20-minute phone consultation by clicking the button.

When designing a dust collection system, the ductwork is like the highways of the system. They allow the dust to move from the area of production to the dust collector. The dust should move fast enough so it doesn’t fall out while not moving too fast to cause undue wear and pressure drop. What this means is when you are designing your dust collector ductwork, pay attention to the ductwork diameters. When picking the ductwork diameters throughout the system, make sure the velocities correlate with the design velocities shown below.

Low Velocity Causes Dust Build-Up

A velocity that is too low will cause major issues in your ductwork. Dust will fall out and begin to pile up in the ductwork. This will do three (3) things:

• The dust builds up, decreasing the area of the ductwork, until the open area is large enough to get the velocity back up within the range to prevent further dust buildup.
• Dust buildup will increase the weight of the ductwork, and could cause issues with the support of the ductwork.
• If the dust is explosive, the dust buildup creates fuel for an incident and could cause serious problems.

The table below is from the Industrial Ventilation Booklet (5-1) and gives the velocity ranges of various applications and dusts.

How Tough Dust Can Affect Your Dust Collection System

Watch this video from the Dust Efficiency Clinic and learn how to deal with all these tough dust issues.

As always the Dust Efficiency Clinic offers its ‘outside the box’ thinking and solutions to your tough dust problems.

To learn more about which dust collector, please contact our experts at 440-543-7400 or visit our website: www.dustcollectorhq.com.

To improve efficiency and safety, there is no substitute for an on-site inspection by an experienced expert. Click below to start with a free 20-minute phone consultation by clicking the button.

Cyclones do not stand alone in most applications; rather, they require additional equipment to function properly. Depending on your specific application, this equipment can include an airlock, exhaust fan, explosion protection, instrumentation, insulation, vibrator, and even ductwork. Moreover, a cyclone can be purchased either as a complete system with all the necessary equipment or by itself to be integrated into an existing system. In either case, the system is then assembled by the end user or a third party. Often, the total cost of the accessory equipment exceeds that of the cyclone itself. Below is a brief description of these potential accessories and how they impact the cyclone’s performance.

Airlock

An airlock is essential for the proper operation of a cyclone.  It isolates the cyclone from the outside atmosphere.  Without it, material will fly out the bottom or get re-entrained in the system.  Airlocks could be a simple extended hopper (55 gallon drum), rotary valve, or specialized valves like the double dump valve or trickle valve.  Special designed valves are available for quick cleaning applications and explosive applications.

Explosion Protection

Explosion Protection is a very important consideration for dust collectors as about 70% of dusts are explosive. The equipment that protects against explosions can add significant cost the cyclone.  Explosion protection equipment such as explosion vents, isolation valves, chemical suppression, and isolation systems can all quickly increase the price of a cyclone.  This equipment is required for explosive applications. 

Exhaust Fans

Exhaust fans are required on every dust collection system. They provide the motive force required to pull air through the system.  When selecting the fan, be sure to take into account all ductwork and equipment.    It is best to install the fan downstream of all dust collectors so that the most efficient impeller designs can be used.  This will save money on operational costs.  However, if the fan needs to be installed in high dust areas, there are impellers designed for these operations.

Instrumentation 

Instrumentation for cyclones are rather simple compared to other dust collectors. The main instrumentation used on cyclones are differential pressure gages/transmitters and level switches for the hoppers.  Explosive applications can have special instrumentation and some applications will monitor temperature and humidity for equipment downstream of the cyclone.  But for most standard cyclone applications, differential pressure is the only recommended measurement.

Insulation, Heat Tracing, Steam Jacketing

Insulation, heat tracing, steam jacketing are required for special applications. These can add significant expense to the cyclone.  Insulation and heat tracing can be done at the fabricator but usually are done onsite to prevent damage in shipping and installation.  Steam jacketing must be done in the design and fabrication phase and can add significant cost to the cyclone.

Vibrators or Air Jets

Vibrators or air jets are used in applications where material tends to bridge in the hopper. Typically, vibrators can be added after installation and help prevent the hopper from bridging. Similarly, air jets blast air into the hopper to break up any bridges, allowing material to flow smoothly through the airlock. Ideally, however, the connections for these devices should be included in the cyclone design and installed on-site from the start.

In summary, cyclone design and costs depend on the size and construction needed for your specific application. Furthermore, special applications may require expensive equipment and design modifications, which can significantly increase the overall cost. Therefore, when selecting a cyclone for your application, it is important to consider all factors in your cost estimate to ensure an accurate and realistic budget.

To learn more about which dust collector, please contact our experts at 440-543-7400 or visit our website: www.dustcollectorhq.com.

To improve efficiency and safety, there is no substitute for an on-site inspection by an experienced expert. Click below to start with a free 20-minute phone consultation by clicking the button.

Dust collection systems require the proper airflow to operate correctly.  Without the correct air flow, dust will not be removed from collection points and the collection equipment (baghouse, cartridge collectors, cyclones, etc.) will not operate with maximum efficiency. However, if too much air is being pulled through the system, a variety of issues might ensue, such as product being lost, removal efficiency lowered, utility usage increased.

Conventional Way to Measure Airflow

The normal way to measure airflow is to insert a pitot tube in the ductwork to measure the air velocity in an airstream, and then calculate the velocity (and airflow).  This is a manual process that requires a trained individual.  It is time consuming and to a certain degree an art, since the velocity in a ductwork changes depending how close to the wall you are.

Effective Way to Measure Airflow

Obviously, you cannot walk next to a piece of equipment or meter and check the velocity through the ductwork.  However, if you have a cyclone dust collector you can.  Cyclone pressure drops are based on the airflow through them.  The more air you send through a cyclone, the higher the pressure drop.  Each cyclone design has its own equation to determine pressure drop based on the airflow.  With this equation, you can estimate the airflow based on the pressure drop in your cyclone.

The GPC Dust Collector is an efficient way to handle your dust collecting needs. Simply click below for direct access to the GPC spec.

Exhaust Fans: The Motive Force of a Dust Collection System

In this video, Aerodyne discusses how system changes and fan performance affect your dust collection system.

To learn more about which dust collector, please contact our experts at 440-543-7400 or visit our website: www.dustcollectorhq.com.

It’s common knowledge that getting regular oil changes is important to a car’s health and longevity. Dust collectors need regular maintenance too, in the form of dust collector evaluations. The dust collection system consists of hoods, ductwork, air-material separators (cyclones, baghouse, cartridge collectors, wet scrubbers, etc.), explosion protection equipment, airlocks, instrumentation, and exhaust fans. 

All of these items should be checked at least once a year to make sure they are operating correctly. The following points briefly describe what each piece of equipment needs during your yearly dust collection system evaluations:

1. Hoods

• Visual inspection to make sure they haven’t been damaged.
• Measure airflow velocity to make sure they are collecting the design airflow.
• If a local damper is located by hood for balancing, make sure it is operable and in the correct position.

2. Ductwork

• Visual inspection to make sure no holes have developed.
• Measure air velocity through ductwork to make sure designed airflow is correct.
• If possible, visual inspection of the duct’s insides to make sure dust isn’t building up.

3. Air Material Separators

• Measure pressure drop across the separator to see if it is within parameters.
• Inspect cleaning process (baghouses and cartridge collectors) that they are operating properly (timing, valves opening, air pressure, etc.). See operations and maintenance manual.  Often time, listening to the system will let you know if it is operating correctly.
• Monitor recycle line pressure and overflow in wet scrubbers.
• Visual inspection of vessel walls to be sure there are no holes.

4. Explosion Protection Equipment

• NFPA compliance requires yearly inspections– following the manufacturers’ manual is very important so the explosion protection equipment will protect the facility, equipment, and workers as it was designed.
• Some explosion protection equipment such as chemical suppression should be examined by factory trained personnel.

5. Airlocks

• Rotary valves
  • Should be checked to see they are still spinning
  • Bearings should be greased and temperature measured to make sure they aren’t overheating
  • On explosive applications the rotor clearance should be measured to make sure it still complies with NFPA 69.
• Pneumatic valves (slide gates, double flap valves, etc.)
  • Valves should be tested to make sure they are still operating as designed.
  • Air pressure should be measured, to be sure it is still within design parameters.
• Motorized valves (rotary valve, double flap valves, etc.)
  • Bearings should be greased
  • Bearing temperature should be measured to be sure they aren’t overheating
• Trickle valves
  • The sleeve should be inspected to be sure it is still sealing
  • During operation confirm that material is still draining and material hasn’t bridged above it.

6. Instrumentation

• Level gages, pressure gages, VFDs, pH meters, zero speed switches, etc. all have different maintenance requirements.
• Follow the manual of the specific model for maintenance and inspection.

7. Exhaust Fans

• The fan housing should be inspected to make sure no holes are present.
• The voltage and amps should be measured to make sure it is operating at its design condition.
• The bearings should be greased and temperature checked to be sure they aren’t overheating.
• The fan’s vibration should be checked along with checking to see if any abnormal noise is emanating from the fan.

To improve efficiency and safety, there is no substitute for an on-site inspection by an experienced expert. Click here to talk to an engineer about your application. 

When it is time to add a dust collector to your application, it’s critical to find the right place for the dust collector.  This isn’t always easy.  New facilities are usually designed around the equipment that is being installed.  However when a system in an existing facility is modified or installed, you will have limited space to install the dust collector system.  There are four factors that you should take into account when finding a place for your dust collector. (Part 3 of 4)

Distance from Process

Ideally installing the dust collector should be located next to the dust generation.  However, this isn’t always possible.  There are space constraints, safety and noise concerns and process requirements that all affect the placement of the dust collector.  However, based on this, you should place the dust collector as close as possible to the process.  This decreases cost with less ductwork required.  You will also want to use as straight as possible runs of ductwork. Short, straight ductwork will keep the pressure drop of the system low allowing you to install a smaller quieter blower.  It also helps prevent dust build up in the ductwork which can cause operational issues and be a fire/explosion hazard.

Smaller Fans

Smaller fans usually mean lower horsepower motors.  This translates into lower operating cost for the fan.  And shorter ductwork requires less cleaning, thereby less time for maintenance on the whole system.  If long distances are required, look at using local pre-filters to lower dust loading going through ductwork.  This will help solve some of the issues such as dust buildup in the ductwork.

Additional Insight

Having an expert conduct a dust system evaluation can be extremely helpful during this process. System evaluations can also be part of the preparation process for a Dust Hazard Analysis, or DHA.

To learn more about dust collector, please contact our experts at 440-543-7400 or visit our website: www.dustcollectorhq.com or click here to get our free whitepaper: Top 5 Reasons to Use a Cyclone as a Pre-filter.

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.

• It is a fire / explosion hazard. If your system has a low dust loading, small enough that there isn’t enough material to support an explosion (below MEC), dust collecting in the ductwork could put the system above the MEC, thereby making the system an explosion hazard.
• Dust collecting in the ductwork causes the effective diameter of the ductwork to decrease. This causes the pressure drop through the system to increase, which will decrease the airflow through the system.  Lower airflow will cause more dust to escape the pickup hoods, thereby causing greater housekeeping, maintenance, etc.
• Dust building up in ductwork will also cause your ductwork to weigh much more. Depending on the weight the supports were designed for, if too much dust builds up, your ductwork could fall down, thereby possibly creating a dust cloud that could be explosive.

If the air velocity is too high, the static pressure of your system will be high.  This will require you to operate the exhaust fan at a higher speed.  This could increase the noise, power used and wear and tear.  High air velocity could also increase the erosion of the ductwork, thereby developing holes in the ductwork which will leak air into the system and decrease the actual airflow at the pickup points.

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Watch for our upcoming article on sizing of ductwork for your dust collection system.

If you are having operational issues on your dust collection system, contact Aerodyne at 440-543-7400 or dc@dustcollectorhq.com.