Cyclone Pre-filters can filter out 90% or more particulate before it reaches downstream filters, significantly reducing fabric filter wear and protecting other industrial dust collection equipment.

The Unique Dust Challenges In Foundries:

Foundries are hot, dusty places—factories where metal castings and other casting services come to life. Castings are produced by melting metal into a liquid, pouring it into molds, and allowing it to solidify. Sand, characterized as an abrasive, is used in metal casting for molding and core making, and silica is typically a key ingredient in molten metal shaping due to its uniform physical characteristics. Unfortunately, silica poses major health risks to humans if inhaled, and so the airborne dust created from sand molds and casting cleanups must be managed properly. The majority of manufactured goods rely in some way on the castings produced by foundries, and like other areas of manufacturing, the dust they produce must be managed via a dust collection system to keep the working environment safe and compliant.

Why Fabric Filters Struggle With Heavy Loading:

Baghouse and cartridge filter collectors are a core piece of many foundry dust collection systems, and are generally very well suited to filter dust from the air in these operations; situated towards the end of the dust collection system, they take on heavy loads of metal, sand, and silica. Depending on the particle size and loading rate of the dust particulate, these fabric filters can suffer from plugging or overloading, inhibiting the airflow of the dust collection system and allowing dust to escape and settle in work areas.

This is a serious concern for foundry personnel because of the increased risk of health hazards and potential explosions.

How Cyclone Pre-filters work:

Enter the cyclone pre-filter. Widely endorsed as a proactive measure for reducing filter loading and increasing dust collection system efficiency, they can be placed upstream of fabric filters to separate out the majority of particulate before it comes in contact with said filters. Cyclones also serve as spark arrestors, increasing the amount of time a spark has to travel before it reaches the filter, and helping to cool down sparks that touch the walls but are not captured—an added bonus for foundry applications.

Cyclones use centrifugal force to capture and remove dust from the airstream, and can often remove 90% or more particulate before it comes in contact with downstream fabric filters. They’re one of the simplest dust collectors available on the market: dirty air enters the cyclone’s inlet and swirls around the separation chamber, where centrifugal forces then force dust out towards the walls.

Once the mixture of air and dust gets down near the hopper, the air changes direction (called vortex reversal) and leaves through the center of the cyclone separation chamber. The solid particles that were concentrated near the wall fall into the hopper and are then removed from the hopper via the airlock.

Any small dust that makes it through the cyclone is then captured by downstream fabric filters, easing the load on the filters themselves and drastically changing the way that dust is managed in the system. Any sparks from the process and the majority of abrasive dust are removed before they can reach the filters, reducing filter cleaning requirements, fire risk, and the amount of compressed air required for cleaning (pulse jet type). Significant savings can be seen if the compressor loading can be downsized for a facility. Ultimately, less dust escapes into the surrounding work areas—lowering the risk of silica damage to employees, and decreasing the risk of explosions or fires.

Aerodyne’s GPC cyclones are compact models with removal capacities comparable to those of traditional cyclones; they differ from traditional cyclones in that they’re shorter, can be configured horizontally, and have an internal ground plate that acts as an integral vortex breaker. Cyclones can be installed in close proximity to areas where dust is generated, and where a larger, traditional cyclone may not fit, which allows the material to be collected and then directly re-entered into the process. This is critical in foundries, where much of the sand and casting materials are recycled heavily. An optional cleanout door can be configured on the cyclone’s backplate for easy access.

GPC Cyclone Specifications:

• proactive measure for reducing filter loading and increasing dust collection system efficiency by filtering majority of particulate ahead of filters
• serves as a spark arrestor
• designed to be installed vertically or horizontally with little effect on collection efficiencies
• utilizes centrifugal force + a ground plate to maximize collection potential
• handles abrasive materials
• eases filter loading to reduce cleaning cycles and increase filter lifetime
• can be installed in close proximity to areas where dust is generated and then directly re-entered into the surrounding processes
• optional “easy clean door”
• 7 sizes under 8 ft³ per NFPA 654
• Ideal for applications with limited space

Dust collection systems perform best in any industry when each of their components is optimized for its role in the system. When fabric filters like baghouses or cartridge collectors take the brunt of heavy dust loading by themselves, it’s a matter of time before efficiency becomes an issue. Implementing a high-efficiency cyclone pre-filter like the GPC shifts the heavy loading burden upstream, often capturing 90% or more of particulate, helping to intercept sparks, and ultimately stabilize airflow before it reaches the filters.

The GPC’s compact footprint and flexibility of installation make it particularly suited for space constrained foundry applications. Improving dust collection system performance doesn’t always translate to replacing the collector itself, but improving the system around the collector by evaluating upstream separation.

Cyclones also need to be constructed so that they meet the specifications and requirements of the applications they are going in.  Some applications, like woodworking or where the material being collected is waste, don’t need any special constructions.  Applications such as food and pharmaceuticals can be very specific.  Every application, customer, process, and facility has their own set of requirements.  These could include a special quick clean access or a higher weld spec to prevent accumulation in the vessel.

Quick Clean

Quick Clean design allows for the cyclone to be easily accessed for cleaning. It is often used in food and pharmaceutical applications.  These applications usually have a strict cleaning protocol and/or require cleaning between batches.  The design changes required for quick clean design can often significantly increase the price of a cyclone.  Often times it will require redesign of the standard cyclone to allow access and minimize material buildup.  Horizontal cyclones are often best for these situations.

Special Welds

Special welds are required in most food applications. The welds are often areas where material can build up and contaminate the material being collected in the cyclone.  To prevent this, the welds are often required to be ground down.  This is a time consuming process and is done individually with power tools.  Depending on the specification, special welds can often significantly increase the price of the cyclone, even as much as doubling the cost. 

Often times, the welds will require specific welders in a shop to work on the unit, thereby increasing the lead time and cost.  When you are specifying special welds, it’s often a good idea to have a sample or a picture of the weld you are looking for so the fabricator and end user are on the same page.  See the drawing below for an example of a sample.

Special Finishing

Special finishing of the materials of construction is another requirement in many stainless steel applications. Some food and pharmaceutical applications require the metal to be finished or polished to a certain specification.  Usually, the internal finishing is the most critical due to it being in contact with product, but often times the facility has a specification on the external too.  This is often for cleaning and uniformity in the facility.  Special finishing of the metals can often significantly increase the price of the cyclone.  Often times, with the higher finishes allowance has to be made in the pricing for discarding material that doesn’t meet to specification after it has been worked on.

How Do Horizontal Dust Collectors Work?

To learn more about the right dust collection solutions for your application, 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 here to contact a member of our engineering team.