Well-Designed Hoods

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. The amount of airflow required by a hood is dependent on a variety of factors including, how the dust is generated, distance of the hood to the equipment, and the size and shape of the hood. How the dust is being generated and the distance of the hood from the equipment both affect the minimum velocity the air needs in the hood. While the size and shape of the hood affects the total airflow that hood requires for proper dust collection (velocity x area= airflow).

A properly designed dust collection system will have enough velocity in the hood to collect the dust being generated. The exhaust fan will have enough static pressure to keep this velocity after all the pressure drops in the system (ductwork, pre-filter and dust collector). Now, if for some reason the airflow is not at the design velocity at the hood, then the dust collection from the process will be affected.

When The Airflow Is Too High

If there is too high of an airflow in the system, the airflow through the hood will also be too high. This means that the velocity through the hood is also higher than designed. The greater airflow (velocity) will mean the hood will have greater suction around the equipment. While the hood will pick up the nuisance dust that you want collected, it could also collect material that you want to stay on a conveyor, table, etc. This will cause higher dust loading in the system. It will also mean that the dust collector is collecting valuable material that should be used in the process or is product. This will increase the waste of the system, thereby increasing costs. The greater dust loading in the system will also cause more maintenance in the ductwork and dust collector.

When The Airflow Is Too Low

If there is too low of an airflow in the system, then the airflow through the hood will also be too low. This means that the velocity through the hood is lower. This will allow dust that is being generated by the process equipment to escape the dust collection system by not being collected in the first place. The dust that escapes the dust collection system will settle on the surrounding equipment. This will cause increased housekeeping in the plant to prevent dust buildup. Dust buildup could become a fire and explosion hazard and/or cause increased maintenance on plant equipment.

Monitoring the airflow in the dust collection system will allow you to make sure the airflow at the pickup hoods is correct which will prevent dust from escaping from the system which would cause additional issues or too much material being collected which would cause loss of profits.

To improve efficiency and safety, there is no substitute for an on-site inspection by an experienced expert. Click here to connect with a member of the Aerodyne engineering team about a better hood for your dust collection system. 

What problems can arise from using the wrong hood?

The hood should be designed so that it will capture the dust without letting dust escape. This can often be difficult as the hood will need to be designed to pull air from all the areas generating dust while also provide the required access of the operator / machine.

Using the wrong hood can cause:

• Dust to escape the hood, thereby causing health, safety, and maintenance issues.
• Too much dust is captured, removing product or components from the process.
• Too much air is used, increasing the system size and cost.

When installing a dust collector system, focus on the hood design. The hood captures dust at its source, so choosing the right one is critical. Carefully select a hood that fits your application, considering airflow, dust type, and workspace layout. Don’t pick the cheapest option just to save money, because a poorly designed or undersized hood can make your entire system fail, letting dust escape, increasing maintenance, and creating safety hazards. Investing in the right hood upfront ensures your system works efficiently, protects workers, and keeps the workspace clean and safe.

For more dust collection and material handling literature, visit our library of case studies, test results, and application content on our website at www.dustcollectorhq.com.

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

Dust collectors have hoppers under the collection chambers to channel the dust out of the system for use or disposal. The hoppers are not designed to be used to collect and store the material, but rather as a place for the material to temporarily collect before passing through the airlock and out of the system. 

Dust Build-Up in Hopper

Depending on the material being collected and the characteristics of it, dust may temporarily build up in the hopper until it can pass through the airlock. Applications that have periodic high loading or applications that have materials with irregular shapes, are sticky, or hygroscopic could all build up in the hopper and form a bridge or rat hole by the dust discharge opening. When this happens, one of the most common solutions is to install a vibrator on the hopper.   The vibrator works by hitting the side of the walls which can cause the material to break up and fall through the dust discharge flange and leave the system.

The Purpose of Vibrator on Hopper

Vibrators for dust collector hoppers can be powered either pneumatically or electrically, giving you flexibility depending on your system’s setup and requirements. In addition, they serve two main purposes: they can continuously agitate the hopper to prevent any material from bridging, or alternatively, they can be operated periodically to break up any bridging that has already occurred. Furthermore, the choice of operation mode depends on the type of material being collected, the frequency of buildup, and the overall design of the dust collection system.

Therefore, when installing a vibrator, it is crucial to communicate your intended usage to the manufacturer. By doing so, they can recommend the most suitable vibrator for your specific application, ensuring optimal performance, reducing maintenance issues, and preventing potential blockages in the hopper. Ultimately, proper selection and installation of the vibrator help maintain smooth material flow and enhance the efficiency and safety of the entire dust collection system.

For more dust collection and material handling literature, visit our library of resources at www.dustcollectorhq.com.

To improve efficiency and safety, there is no substitute for an on-site inspection by an experienced expert. Discuss your application with a member of our engineering team through here– 100% free. 

The post How Vibrators Can Help Hopper Flow? | Aerodyne first appeared on Aerodyne Environmental.]]> https://www.dustcollectorhq.com/how-do-i-inspect-my-dust-collection-system/ Fri, 21 Jun 2019 19:49:00 +0000 https://www.dustcollectorhq.com/how-do-i-inspect-my-dust-collection-system/ How Do I Inspect My Dust Collection System?

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:

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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. 

The post Dust Collector Evaluations first appeared on Aerodyne Environmental.]]>

1. direct the dust away from the employees and equipment, even if the dust collector is not operating correctly
2. allow dust to be captured at the lowest airflow possible, saving you money

If a hood is improperly designed it will not capture the dust from an application, no matter how well your dust collector or fan is designed.

A few things to remember on hood design:

• Place the hood as close to the dust generating area / equipment as feasibly possible to lower the airflow required
• Use the Industrial Ventilation Handbook to help you design / evaluate your hood
  1. Location
  2. Geometry
  3. Pickup velocity
• If you use of local dampers for greater flexibility in the future remember they could allow un-intentional changes

If you have questions about your hood design or your dust collection systems our consultants are here to help.

Contact Aerodyne at 440-543-7400 or dc@dustcollectorhq.com to help you problem solve your dust collection problems.

Dust collection systems consist of four major components. All of them are important and can cause a dust collection system to underperform. The major components are the exhaust fan, dust collector, ductwork, and hoods/pickup points. While the exhaust fan provides the motive power to collect dusty air, its performance is affected by each of the other components. This means that if one of these components isn’t operating as designed, the whole dust collection system will be affected.

Dust collection ductwork is usually by far the largest component and often the most overlooked. Depending on the size of your industrial dust collection system, the ductwork can span hundreds of feet and have dozens of branch lines. The ductwork is like railroad tracks—it moves the dusty air from one place to another.

Often times, additional lines will be added to a dust collector system after installation. Without proper evaluation of the system, this could negatively affect the performance of the whole system. This means that just because the dust collector system was operating correctly before, it might not after an additional pickup point or hood is added. What happens is that when you add additional pickup points, you change the balancing of the system. This could change the airflow to each and every hood and pickup point in the system, so while the system was originally adequately venting an area, it might not after a change.

Several steps can help address these issues, including changing fan speed, adding dampers, modifying ductwork, or rebalancing the dust collection system. The main thing you need to keep in mind is that if you slow the airflow through ductwork too much, you begin to build up dust within the line.  This will further restrict your airflow and become a fire / explosion hazard.

Whenever you are planning to modify your dust collection system, review the system parameters or hire someone to review so that you do not cause additional issues.

Learn about the questions you should be asking to make sure you’re buying the right dust collector for your application. Get your whitepaper now.

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

Hoods / Pickup Points

Hoods mark the start of an industrial dust collection system. Hoods are designed for providing a specific airflow at a minimum velocity while picking up particulate in the air.  The hood type, location and number are usually specific for your application.  The Industrial Ventilation Manual, the standard for ventilation put out by the American Conference of Industrial Governmental Hygienists, provides guidelines for velocity ranges to provide the proper ventilation.  A velocity lower than suggested could cause dust to escape the hood.  Adding additional hoods to an existing system could cause the airflow (thereby pickup velocity) to drop below the minimum suggested, thereby making a notable reduction of performance.

Ductwork

If dust and airflow are blood, ductwork is the circulatory system. The ductwork of a properly designed ventilation system should be sized so that it has the lowest possible pressure drop and have a minimum velocity.  Best ductwork practices for avoiding a pressure drop include keeping the ductwork as straight as possible, minimizing turns, and keeping the duct size larger.  Since the ducts are carrying dust, a minimum velocity is required lest the dust settle in straight sections.  These accumulations will cause increased resistance and are a fire and explosive hazard.   Usually, a velocity of the air over 4,000 FPM prevents dust from accumulating.  Keeping ductwork in a standard size keeps costs down and assures availability if additional or replacement ductwork must be added.

Dust Collectors

Some dust collectors are less sensitive to added airflow than others.  A cyclone’s pressure drop will increase as airflow increases through the system, but a baghouse or cartridge collector’s removal efficiency will decrease if airflow is increased too much.  Many of these are very particulate specific; a cartridge collector for an airstream containing wood dust could handle higher airflows than one for silica dust.  Contacting the dust collector manufacturers is the best way to understand the capabilities of a collector.

Exhaust fans

The exhaust fan is the most important equipment in a dust collection system, providing the motive force to collect the air-dust mixture.  In many cases, companies will add additional pickup points and not change the fan, causing less air to be pulled from each of the existing pickup point.  When looking at the airflow in a dust collection system, make sure to calculate the total airflow and static pressure required, then check to see if the existing fan can handle it under different conditions, such as open dampers or increased speeds. If not, a new fan will be required.

For more information on how Aerodyne’s GPC line of compact, efficient dust collectors can fit into your existing industrial dust collection system and be tailored to your airflow, click the button below, call us at (440) 543-7400, or email us at dc@dustcollectorhq.com.