In The News: Chemical Safety Board Releases Video on Combustible Dust

The U.S. Chemical Safety Board (CSB), an independent federal agency, has released a new safety video entitled, "Combustible Dust: An Insidious Hazard." It features outstanding animations that recreate the events and conditions leading to three major industrial dust accidents involving combustible dust. You can watch the YouTube video here.

The issue of combustible dust must be addressed when considering the installation of an industrial dust collector. Please watch this video to learn of surprising dangers that you probably don't realize exist. For further reading on all aspects of combustible dust, be sure to visit http://dustexplosions.blogspot.com/. This blog site offers extensive and resources on the subject. Always feel free to contact us here at Farr to answer your questions regarding your particular application.

Case Study: Sink Manufacturer's Dust Problems Down the Drain

Sink Factory, Inc. (SFI) is a manufacturer of cast polymer products. In 2004, they started their business in a facility that already had a baghouse dust collector in place. However, the volume of dust generated by the grinding and sanding of thr cast sinks proved to be too great a challenge for the undersized collection system. Employees with protective masks worked in an environment of dust laden air and thick layers of settled particulate.

Sound similar to your situation? Read the solution to this challenge and learn how a unique installation of two dust collection booths handled the massive dust loading in this case study. Great photos here.

Employee Safety, Equipment Protection or Code Compliance: Why do manufacturers install dust collection equipment?

Just about every type of manufacturing process generates some sort of dust or fume. At what point(s) does dust-laden air become a nuisance? ...a health hazard? ...a safety hazard? ...an equipment liability? ...illegal? Are manufacturers aware of such conditions in their businesses? One would certainly hope so. What motivates a manufacturer to install dust or fume collectors?

In our experience, most companies buy dust collectors because they have to, not because they want to. Of these, the majority are trying to comply with codes to keep their operation running. The second largest group who buy industrial dust collectors are those concerned with the detrimental effect that fugitive dust has on capital equipment. Finally, there's a small percentage of manufacturers who install dust or fume collectors primarily for the sake of health and safety for their employees.

All the above are valid reasons. Is one more important than the other? To whom? What can be done to help/educate manfacturers on this issue? Please feel free to comment here and express your opinion.

Safely Applying Dust Collectors to Thermal/Flame Spray Applications

Because of the various types of thermal spray applications and their effects on the operation of dust collectors, it's important to identify your specific thermal spray operation. Each process involves different shaped and sized particles along with varying loads. Additionally, strict safety procedures need to be addressed as almost all thermal spray applications can be explosive and/or flammable. Types of thermal sprays include Electric Arc Wire (EAW) spraying, powder spraying, electric arc spraying, HVOF and plasma spraying.

The potential for fire and explosion is very real when dealing with thermal spray and dust collectors. It is imperative that proper explosion venting and other safety concerns are addressed. Explosion vents, sprinkler kits, flame retardant cartridges and possibly spark traps all need to be addressed during the application process. Continue reading about Dust Collector Sizing Recommendations for Thermal/Flame Spray.

FAQ: What is a "gold cone."

In the industrial dust collection business, a "gold cone" refers to a unique filter cartridge manufactured by Farr Air Pollution Control in Jonesboro, AR. It refers to an inner cone of filter media within the outer, cylindrical pleat pack. This inner cone of media provides expanded capacity, uniform dispersion of back-pulsed air and opens up more usable space for airflow in the dust collector.

This additional use of wide-spaced media pleats also permits collected dust to be dislodged easier from between the pleats during the cleaning cycle, unlike typical industry packed media pleats. The Gold Cone® media has the same filtration efficiency as the outer media pack at 99.999% separation efficiency down to 0.5 micron by weight. Data sheets on the various Gold Cone filters offered can be requested/downloaded here.

Case Study: Body Parts Processed with Clear Lungs in Dust Booths

Ogihara American Corporation is a manufacturer/supplier of automotive body parts for Mercedes-Benz. The sanding and grinding operations in this plant caused a dust cloud that drifted across the whole plant, settled on the floor (and everything else) and was swept up daily. Without a dedicated dust collection system in place, workers wore respirators for safety. However, when the air conditioning filters began to require change-out during sanding operations, the maintenance crew knew something had to be done. Further compounding the problem was the limitation of space which the 10 workstations already occupied.

Continue reading of how the solution to the problem was designed and implemented at Ogihara here. If you have an application where a dust collecting booth that encapsulates the dust generating processes makes more sense than a central dust collection system, talk with your supplier about these types of systems.

FAQ: Can I place a dust collector inside the facility if we are handling a material with a high Kst?

Yes, a dust collector can be placed inside the confines of a facility even though it may have a relatively high deflagration index (Kst). Both explosion venting and chemical suppression may be options depending on the location of the collector within the facility and its vicinity to an outside wall or ceiling.

Explosion venting can be selected if the dust collector's locale in the facility is within acceptable ducting distance limits as dictated by NFPA 68 calculations. Venting can be accomplished either horizontally or vertically depending on existing space restrictions and utility obstructions that may exist. There is also a flameless venting option available that allows the deflagration to vent inside the facility. This method extinguishes the flame from the vented explosion not allowing it to exit the device.

Chemical suppression (and chemical isolation for the ducting) is the preferred method of deflagration protection for hazardous materials. Explosion suppression systems are designed to detect and chemically suppress an explosion in its earliest stages - before an explosion can cause a disaster or become catastrophic. This prevents the flame and material from being released from the collector into the surrounding environment, protecting personnel and property.

- For more information, read the informative article, Asking the Right Questions About Cartridge Dust Collection. Another relevant article is Five Ways New Explosion Venting Requirements For Dust Collectors Affect You.

Video: Containment Dust Collectors for Pharmaceutical or Hazardous Dusts

For safety, some dust collection applications require isolation of the collected dust from contact with workers. This may be from processes involving pharmaceutical dust like table presses, table coating, fluid bed drying, spray drying, blending, granulation and especially general room ventilation. Containment dust collectors have special features and methods to replace the dirty filter cartridges and dispose of the collected, potent/hazardous dust being discharged. This video demonstrates these safe-change methods:

As you see, the cartridge filters are safely replaced by a two-person crew with the bag-in/bag-out (BIBO) safe-change replacement system. At the discharge of the colletor, the dust is contained within a continuous liner. For more information go to Dust Collection for Pharmaceutical Solid Dosage Manufacturing.

FAQ: Which dust collectors are the easiest for changing the filters?

Now here's a great question - usually from the maintenance guy, not the purchasing guy. In reference to cartridge filter style dust collectors, you're going to run across several different configurations for opening/closing the access points as well as removing/installing the filters. Let me briefly address what is typical, what is unique and let you decided for yourself.

Most horizontal cartridge style dust collectors have multiple, roundish covers that separate from the collector housing. Of these, different manufacturers offer varying methods for attaching the covers. Some are cover assemblies that must be oriented and navigated back on in a specific way so components behind the cover line up and lock. Other cover designs with a locking procedure that is visible use threaded rods, knobs or nuts. All these loose items are retained atop an elevated access platform while the horizontal cartridges are removed and replaced with new ones.

The easiest industrial dust collectors for changing the cartridge filters are those that offer quick access, require no tools and have no loose hardware to get lost. Look for a minimal quantity of access doors that are permanently attached and securely seal against the collector housing. Also, unless you want to be covered in dust when removing dirty filters above chest height, look for collectors that allow removal at a comfortable, safe level. More information and a video on easy changing of filter cartridges can be viewed here.

Case Study: Hay Exporter Reaches Last Straw with Dust Issues

As an exporter of timothy hay and alfalfa to the Far East, Ward Rugh, Inc. in Ellensburg, WA generated much fugitive dust in their operation as they compacted bales for shipment. Expansion to the operation contributed to the housekeeping challenge and the increased processing of hay, a common allergen, contributed to worker discomfort.

Hay dust presents challenges for dust collection similar to many fibrous dust types. It's lightweight and consists of a wide range of strand lengths and thicknesses. A low air-to-media ratio is called for to allow pulsing cleaning of the lightweight dust without re-entrainment back onto the filters. Nylon overbags on the filters prevent the strands from getting wedged in the pleats and bridging across. Read the full story of how Ward Rugh solved their dust issues, keeping the process area clean and letting everyone breathe easier.

FAQ: What are the main differences and benefits between dust collectors with vertical cartridges vs. horizontal cartridges?

The reason that some collectors had filter cartridges laying horizontally on their side was to overcome the upward can velocity effects that occured in traditional baghouses and early cartridge collectors. Air would enter the hopper and flow up into the filter housing. The dust could only be cleaned off the filters if the up flowing air was slow enough to allow the dust to fight back down through the air stream. This system worked well on heavy dusts, but not on light dusts like weld smoke and fumed silica. It was devised that if you laid the filters horizontally, moving the clean air plenum to one side of the collector, you could expose the dirty air plenum to the top of the collector and thus bring the air into the top of the dust collector. This resulted in a down flow effect helping overcome the upward can velocity issue.

However, the down flow style collector presented many limitations in its inherent nature of laying a filter on its side. The biggest problem is that the dust does not get cleaned off the top of the filter. The dust blinds at least 1/3 of the entire filter because it cannot be cleaned off. This increases the air to media ratio in the collector and has caused premature failure of the filters in many instances. Many operation and maintenance manuals from horizontal cartridge filter manufacturers recommend opening up the collector and rotating the filters monthly to overcome this problem. See figure 1 here. Another major issue with horizontal cartridges is that 100% of the incoming dust is dumped on top of the filters.

Vertical cartridges allow you to overcome upward interstitial can velocities without turning the filters on their side and wasting much of the filter. You cross flow the air into the side of the collector. This is achieved with a high entry inlet that brings the air into the dust collector at the same height as the cartridges themselves. The air is first sent through a series of staggered channel baffles that distribute the air and also act as a classifier, separating out the larger particles and dropping them straight into the hopper without ever seeing the filters. Since the air is brought into the collector at the cartridge level, there is no longer air flowing upward towards the filters. This system combines the benefit of the old down flow style air pattern without turning the filters on their sides and wasting a large portion of the media. For more information, continue reading here.

Keeping Your Seed Processing Plant Clean and Safe

Industrial dust collectors are used in a variety of agricultural seed processing applications such as corn shellers, seed cleaning, seep preparation, seed coating, seed hybrid development and general facility ventilation. Challenges like "bee's wings" and corn silks must be considered. In some cases, nylon overbags can be installed on the cartridges to prevent them from bridging across the cartridges.

Explosion vents manufactured in accordance with NFPA standards should be used on all flammable applications. The collector should be located outside whenever possible or near an exterior wall with the explosion vents ducted per NFPA standards outside the building.

Related blog on a seed processing case study here.

Case Study: Vitamin Manufacturer Takes Double Dose of Dust Collectors and Safety Precautions

Some would say that two identical dust collection systems on a single, centralized vacuum system is redundant, redundant. One vitamin manufacturer who wanted non-stop dust collection on a '24/7' basis would agree! But he'll also tell you that he replaced 10 small dust collectors of different types that were scattered throughout his manufacturing plant, resulting in filter inventory, maintenance and dust disposal that were time consuming and complicated.

In addition, this installation is user-friendly and safer for his employees. An OSHA compliant railed service platform and caged ladder between the two collectors gives his crews easy access and keep his workers safe during filter change-out. Since the dusts being captured are potentially combustible, a chemical suppression system for fire protection, as well as explosion vents in the collector were installed. Read more and view photos of this case study here.

FAQ: Are dust collector filters washable?

In reference to pleated filter media cartridges for industrial dust collectors, the answer is yes...and no! It mostly depends on the filter media that is used or required for a given application. Filters cartridges that are made of spun bond polyester can be washed - that is, removed from the dust collector and washed down with low pressure water. Once completely dry, they can be reinstalled in the collector. Filter cartridges that are made of untreated (cellulose) paper should not get wet at any time.

So when would you use washable filters in a dust collector? These are ideally suited to tough applications including heavy dust loading conditions, hot/moist air streams, high levels of fine particulate, and/or hygroscopic dust properties which may limit performance of cellulosic type filters. In many food/beverage applications, equipment is often required to be washed - inside and out - periodically. Of course, if a filter cartridge is claimed to be washable, be certain that the end caps and any integral metal components are treated to be in contact with water as well. Be sure to ask the filter cartridge supplier (you'd be surprised). Learn more about pleated cartridge filter media types here.