Double dump valves are available in both motorized and pneumatic actuation. To figure out which would be better for you we need to consider your application. A double dump valve is really two (2) valves with flapper plates in series controlled by the same mechanism. At least one of the flapper plates is closed at all time. The main things we need to know are the pressure, temperature, and flow rates along with the area classification the double dump valve will go in.

Motorized Double Dump Valve

A motorized double dump valve uses a cam rotated by a motor and gearbox to open and close each of the dump valves in series. The cam is designed so that at least one valve is closed at all time, thereby providing an airlock. The cam also provides a certain amount of cycles each minute, which controls the amount of material that is available to pass through the valve.

Pneumatic Double Dump Valve

A pneumatic double dump valve uses one pneumatic cylinder on each dump valve to control the operation of it. A timer is used to control the cylinders. The timer cycles cylinders so that one valve is closed at all times.

Differences Between Pneumatic and Motorized Double Dump Valve

Pressure - Motorized double dump valves are limited in the amount of pressure they can handle. The cam drive doesn’t provide direct force on the flap plates. This means that higher pressures and weights will push the flap plate open. The pneumatic valve, however, provides direct pressure on the flap plate so it can handle higher pressures and weights.

Temperature – A motorized double dump valve has a gearbox and motor located next to the housing of the valve. At higher temperatures, this can cause issues with the grease in the gearbox and motor. Also, the cam drive uses wear plates that might degrade faster at higher temperatures. The pneumatic valve, however, can be supplied with high temperature seals on the pneumatic cylinder.

Material Flow Rates – Unlike a rotary valve, which is continuously passing material through, double dump valves fill one chamber while emptying the other. This significantly cuts down on the flow rate through the valve. A motorized double dump valve size is limited due to the cam design. A spool piece cannot easily be installed to increase the volumetric flow through each chamber. While with a pneumatic design, each flap plate is controlled by its own pneumatic cylinder, a spool piece can easily be installed to allow additional material to flow through.

Area Classifications – The electrical classification of the area the valve is being installed can also effect the valve selection. A pneumatic valve has very few electric parts and can be designed to be intrinsically safe. A motorized unit has an electric motor, so the motor must be selected to for the area classification.

When selecting the best double dump valve for your application, look at the pressure, temperature, material flow rate, and area classification.

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When you have a dust collector capturing valuable material, you often have to regularly clean the dust collector to remove the material and if it is perishable, remove it before it contaminates the other material. Some dust collectors are easier to clean than others.

Wet Scrubbers

Wet Scrubbers are pretty much self-cleaning. Since they use water to capture the dust, it pretty much washes the walls and internals regularly. The main issue with wet scrubbers are that if you are trying to use the material (whether in the process or as a product) then you will need to remove it from the water stream (unless having it in a water stream is desirable).

Cyclones

Cyclones are very low maintenance. Since they use centrifugal motion to remove the material, there isn’t much buildup inside the cyclone. So there really aren’t many places to build up. Designing the vessel with access doors will help keep the cleaning easy. Aerodyne’s horizontal cyclone has a unique design that allows you access to the whole cyclone through its back plate.

Fabric Filters

Fabric filters collect the material on the filters (bags/ cartridges). This builds up a layer of material which remains on it for the life of the filter. During cleaning, the material falling off might have recently been captured or material that has been on the filter for an extended period of time. This could contaminate the material being collected.

1. Baghouses require the bag to be removed in order to be cleaned or replaced. Often times this is a very time consuming process and can often require workers to enter the baghouse. If contamination is a serious concern, baghouses should not be used.
2. Cartridge collectors are much easier with replacing the cartridges. Often times this can be done in minutes compared to hours of a baghouse. So you can remove the cartridges, clean them and re-install. This will allow you to clean or replace the filters after each batch, thereby minimizing any contamination.

One option is to install a cyclone dust collector as a pre-filter before your baghouse or cartridge collector. The cyclone will capture the majority of the material without contaminating it for use in your process / product. While the smallest fines will then be captured in the baghouse / cartridge collector for disposal or treatment. This allows you to capture as much of your valuable material with minimal cleaning / contamination while also providing the high removal efficiency for the environment.

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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.

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

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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

 

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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.

 

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When protecting vessels from explosions, one of the most common ways is to install explosion vents. The explosion vent is an engineered weak spot in the vessel that fails when the internal pressure reaches a certain point. This failure allows the pressure to be released in a controlled way so that the entire vessel doesn’t explode. The explosion vent needs to be installed so that the venting is away from any equipment, walkways, roads, picnic areas, etc.

Explosion vents are primarily used when the vessels are located outdoors, however they can be used indoors, if certain criteria is met. To install an explosion vent indoors, the vessel has to be located by an exterior wall. The vent would then be ducted through the wall, so in case of an explosion it is directed outdoors. An indoor explosion vent will usually need to be larger than an outdoor explosion vent. This is due to additional combustion of material in the duct and the inertia of the air mass in the ductwork.

The following is an explanation taken from FM Global 7- 76 Section 3.1.8

During the early part of the venting process, unburned dust is ejected into the duct ahead of the flame front from the vessel. When the flame front moves into the duct, dust starts to burn within the duct and generate additional combustion products. Those combustion products expand in ALL directions, thus slowing down or even reversing the flow out of the vessel and the pressure builds up within the vessel.

Inertia of the air within the duct also increases explosion pressure within the protected vessel. When the explosion vent opens and combustion gases first start flowing into the duct, those gases must push all the air out of the duct. During the time required to eject the air, the pressure continues to grow within the vessel because the combustion gases are obstructed from reaching the open atmosphere. In a long duct, that mass of air can delay the venting of the combustion gases enough to significantly increase the pressure in the vessel.

So if you’re installing a vessel indoors and you want to vent it outside, keep it as close to the outside wall as possible.

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Are you in compliance with the 2018 version of NFPA 68?

Simply click the button for direct access to the webinar to learn more about how to these recent changes may require modifications to your system.

 

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

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In most applications, cyclones do NOT replace baghouses, cartridge collectors, wet scrubbers, electrostatic precipitators, etc. Modern air pollution regulations require dust collectors to provide greater removal efficiencies in the PM2 and PM10 than most cyclones can provide.

How Cyclones work?

Cyclones collect dust by having the contaminated air enter (usually on a tangent) and spin around the cyclones walls until they get to the bottom. The air then reverses and spins up the middle of the vessel and leaves from the top, while the dust falls into the hopper.

The centrifugal forces on the particles and droplets, force them out towards the walls and away from the air exiting the center of the vessel. Cyclones provide high removal of the larger, heavier dust particles and moisture droplets.

The Benefits of Cyclones

Cyclones remove very high percentages of the larger, heavier particles. This means they often remove as much as 80%-95% of the total particles. However the removal efficiency of the smaller, lighter dust isn’t very high. The PM2 and PM 10 particulate will often get through the cyclone in high enough concentrations that the system won’t comply with state, local, and federal standards.

When installed in front of a dust collector (baghouse, cartridge collector, etc.) as a pre-filter, they significantly reduce the loading on the primary dust collector. This helps extend the operational life of the dust collector, increase removal efficiency, and decrease maintenance. Cyclones are often used to lower the loading on a dust collector (baghouse, cartridge collector, wet scrubber). The cyclone removes the large material, allowing the dust collector to get the high removal efficiency on the PM 2 and PM 10 particulate.

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Aerodyne GPC Cyclone Dust Collector

View the animation of the GPC Industrial Dust Collector to see the compact, high efficiency cyclonic design. Unlike typical cyclonic dust collectors, the GPC Industrial Dust Collector uses a ground plate to force vortex reversal in a much shorter space, eliminating the need for a long, tapered body.

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There are multiple ways to collect dust from the air. The most common are:

• Using filters such as bags and pleated filters
• Using centrifugal motion in a cyclone
• Using water (as in a wet scrubber)

The Important of Particle Size

The particle size of the dust is important in all three of these techniques. Basically the larger the dust particles are the easier it is to capture. And inversely, the smaller the particle is the harder it is to capture, which means it’s more likely to pass through the dust collector and out of the exhaust. Bags and filters build up a dust layer that allows air to pass but prevents particles from passing. Cyclones use centrifugal motion to capture particles, which means the larger and heavier the particle is the faster it spins out of the air-stream. Wet scrubbers use water droplets to increase the particle size of the dust, thereby making them easier to capture.

Particle Size Distribution

What this means is that to figure out how effective your dust collector is, a particle size distribution is required. For example, cyclones have a removal efficiency curve that tells you what percentage of particles will be removed at a certain particle size. This can be used to calculate the total removal efficiency when a particle size distribution is provided. Filter bags and cartridges get high dust removal down to around 1 micron in size; however, if most of your dust is sub-micron in size, they will not provide high removal efficiency. And wet scrubbers can be used to increase particle size, but the design must take into account the particle size.

So one of the first steps to correctly select and design a dust collection system is to run a particle size distribution test. This will allow you to pick the best equipment for your application and to make sure it will provide the removal efficiency you require.

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Are you in compliance with the 2018 version of NFPA 68?

Simply click the button for direct access to the webinar to learn more about how to these recent changes may require modifications to your system.

 

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

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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.

 

 

Many dust collectors spend their time operating far below their potential.  Whether the system was designed incorrectly, the process has changed, slow maintenance, or a combination of these, the dust collector isn’t operating at its finest.    One possible solution is to install a pre-filter before your dust collector to help your dust collector to be all it can be!

The following are some signs that your dust collector isn’t operating up to par and you should look at installing a cyclone pre-filters

Filter Collectors (baghouse, cartridge collector, HEPA filters, etc.)

1. There is a high pressure drop across your filters. This is caused by the dust building up on the filters and not being cleaned off fast enough.  The high pressure drop causes the fan to pull less air to compensate, thereby letting more dust out on to the shop floor.
2. Filters are being replaces too fast! The most common filter failures are by developing holes or plugging up.  Both failures are tied to high dust loadings. 
    
   1. One of the ways holes develop is filter cleaning. Pulse-jet dust collectors use high pressure air blown down through the center of the filter to expand the filter off its support structure.  When the pressure disappears the filter returns to its normal size, causing the top layer(s) of dust to fall off the filter.  This regular expansion and contraction will cause holes and tears in the fabric, which then let unfiltered air and dust through the unit. 
   2. Plugging of the filters happens with “Tough” dust or a deficiency of cleaning of the filters. As the filters plug up, the removal efficiency will actually get better because very little air will get through, but this will cause dust to escape from the pickup points  as less and less air is pulled through the system.  So the dust collector system will not be doing the job it is supposed to do.
3. Valuable product or raw material is being disposed in the dust collector waste due to contamination. As stated above, filters build up dust layers to provide the removal efficiency.  Those filters will retain the material over time.  If the material is valuable, this can be a lot of money that is going to waste.  Pre-filters will allow the material to be collected and used in the process or product before it can be contaminated in the filters.

Wet Scrubbers

1. Do you have a high cost of water treatment and disposal of the scrubber blowdown? When wet scrubbers capture particulate, slurry is formed.  This slurry will then have to be disposed.  It will often be sent to a water treatment plant.  The water treatment plant might be dedicated to the facility or municipal.  Either way, additional costs are added to treat the slurry before it is disposed of or reused.  These costs are usually much more than disposing of dry material.  One reason being that dry material weighs much less because there isn’t any water added and the other being that regulations prevent slurries from being put into landfills, etc.  A pre-filter removes a portion of the material before it is put into slurry, thereby saving costs on waste water treatment.
2. Similar to above, since wet scrubbers form slurries, any valuable material collected in the wet scrubber will be in that slurry. So unless the desired state of the material is within the slurry, it will have to be processed to make it useful.  This means additional steps (and expense) are required to recycle the material.  A cyclone pre-filter removes the material dry, before it is in slurry, thereby saving costs.

So before you decide to purchase a new dust collector, look into the benefits of installing a cyclone pre-filter.  You just might save yourself money!

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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. 

 

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

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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 selecting the cyclone for a dust collection process, there are different factors affecting sizing and cost of the cyclone.  The cyclone should be sized to compliment the airflow of the system and the required dust removal efficiency.  Process conditions will dictate suitable materials of construction as well as any special design requirements.

Part 5: Cyclone Orientation (Horizontal vs Vertical)

The cyclone orientation can affect pricing and cyclone selection.  A vertical cyclone has slightly better removal efficiency than a horizontal cyclone.  Horizontal cyclones are much shorter so they can often fit in spaces where vertical cyclones can’t be placed.  The horizontal cyclone can be accessed easier for cleaning and is easier for installing explosion vents when needed.  However, horizontal cyclones have limitations with high concentrations of dust and cost more than vertical cyclones.

In summation, cyclone design and costs are based on the size and construction required in your specific application.  Special applications can require costly equipment and design changes that will increase the cyclone cost significantly.  When selecting a cyclone for your application, be sure to include all the factors in to your cost estimate so you are can accurately determine your budget.

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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.

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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 selecting the cyclone for a dust collection process, there are different factors affecting sizing and cost of the cyclone.  The cyclone should be sized to compliment the airflow of the system and the required dust removal efficiency.  Process conditions will dictate suitable materials of construction as well as any special design requirements.

Part 3: Materials of Construction

Cyclone costs are largely dependent on the materials of construction.  They can be constructed of materials from plastics to special alloys such a Hastelloy or Monel.  The materials of construction should be selected based on the process requirements more than costs. 

These requirements include chemical and corrosion resistance, industry standards, and cleanability. Plastic cyclones are not really suitable for most industrial applications.  They can provide low cost dust control for garage woodworking shops and can be used in wet applications, but they don’t usually last long in dry applications and can have issues with static electricity.

The following chart shows relative costs for cyclones based on the material of construction.

 

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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.

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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 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.

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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.

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

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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.