Velocity in Dust Collection System | Aerodyne Environmental

Air Velocities and Your Ductwork Design | Aerodyne

dust-admin — Mon, 22 Feb 2021 22:49:00 +0000

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.

Nature of Contaminant	Examples	Design Velocity
Vapor, gases, smoke		Any desired velocity (1000-2000 FPM suggested)
Fumes, metal smokes	Welding	2000 – 2500 fpm
Very fine light dust	Cotton lint, wood flour, litho powder	2500 – 3000 fpm
Dry dusts & powders	Fine rubber dust, Bakelite molding, powder dust, jute lint, cotton dust, shavings (light), soap dust, leather shavings	3000 – 3500 fpm
Average industrial dust	Grinding dust, buffing lint (dry), wool jute dust (shaker waste), coffee beans, shoe dust, granite dust, silica flour, general material handling, brick cutting clay dust, foundry (general), limestone dust, packaging and weighing asbestos dust in textile industries	3500 – 4000 fpm
Heavy dusts	Sawdust (heavy and wet), metal turnings, foundry tumbling barrels and shake-out, sand blast dust, wood blocks, hog waste, brass turnings, cast iron boring dust, lead dust	4000 – 4500 fpm
Heavy or moist dusts	Lead dust with small chips, moist cement dust, buffing line (sticky), quick-lime dust	4500 fpm and up

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.

For more dust collection and material handling literature, visit the library tab 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 speak with a member of our engineering team about your application, anytime.

The post Air Velocities and Your Ductwork Design | Aerodyne first appeared on Aerodyne Environmental.

How To Determine the Cost of a Cyclone – Part 2 | Aerodyne

dust-admin — Mon, 24 Feb 2020 19:45:00 +0000

When selecting the best cyclone for your process, there are many different factors that affect the sizing and cost of the cyclone. The cyclone must be sized so that it handles the airflow of the system and components. The proper design for the required removal efficiency must be used. The process will also dictate the materials of construction and special requirements. The location where the cyclone will be installed will influence the cyclone orientation. Cyclones aren’t a stand-alone piece of equipment; support equipment is required for proper operation. Therefore, the scope of supply will affect the cyclone costs and design. The following is a brief description of the different elements that affect cyclone sizing and pricing.

Part 2: Dust Removal Efficiency

The main purpose of a cyclone is to remove material from the airstream. A cyclone will remove a certain percentage of material based on the size of the material. The larger the material, the higher the removal efficiency of the material will be. The density of the material also plays a part in the removal efficiency. Heavier material will see greater removal efficiency.

Faster air velocity in the cyclone will create greater centrifugal motion and a greater force pushing the material out towards the walls. What this means is the higher your pressure drop through the cyclone, the greater the removal efficiency will be. (Assuming the pressure drop isn’t from a badly designed cyclone inlet and outlet) The chart below shows the removal efficiency of a GPC-24 at different pressure drops with material having a specific gravity of 1.0.

Please note the particle shape will also affect the removal efficiency. Spherical material is the easiest to predict while abnormal shapes are the hardest to predict. The above chart assumes a spherical dust.

When selecting the cyclone size, you will have to balance the requirement for the highest removal efficiency against the lowest pressure drop. A smaller cyclone for a specific airflow will provide greater removal efficiency with a lower cyclone cost, but higher operational costs (larger fan due to larger pressure drop).

Specially designed cyclones are available that will increase the material removal efficiency. Ex. Aerodyne manufactures the SplitStream cyclone. These special cyclones are more expensive than standard cyclones but usually can provide higher removal efficiency and other benefits beyond standard cyclones.

5 Signs Your Dust Collection System Needs a Pre-Filter

Watch the video from the Dust Efficiency Clinic discusses how using a pre-filter will optimize your dust collection system.

If you prefer this valuable information in white paper form, get our whitepaper, Top 5 Reasons to Use a Cyclone as a Pre-filter.

To learn more about the right dust collection solutions for your application, please contact our experts at 440-543-7400 or through here.

The post How To Determine the Cost of a Cyclone – Part 2 | Aerodyne first appeared on Aerodyne Environmental.

Why You Should Pay Attention to Air Velocity in Your Dust Collection System

dust-admin — Tue, 21 Nov 2017 20:04:00 +0000

If your air velocity is too low in your ductwork you could get dust dropping out in straight runs. And dust collecting in ductwork is not a very good idea.

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.

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.

The post Why You Should Pay Attention to Air Velocity in Your Dust Collection System first appeared on Aerodyne Environmental.