Shaker baghouses collect dust similar to reverse air baghouses. Dust collects on the inside surface of the shaker filter bags, and then clean air exits through the top of the bag. The main difference is how the bags cleaned.
How to Clean Shaker Filter Bags
Shaker baghouses are engineered so that filters are hung and tensioned from the top of the unit, and at the bottom they are attached to a tube sheet. Mechanically shaking the filter bags is what cleans them. Shaker baghouses only clean while the system is off-line. Shaker baghouse operation is simple and can be seen in applications where no compressed air is available.
Construction of Shaker Filter Bags
Fabric filter bags used in shaker baghouses are typically constructed with woven or light weight media options like polyester sateen, shaker felt, beane knit, and more. Treatments are dependent on a plant’s application and dust characteristics. The most common top and bottom configurations for shaker baghouses are below.
Most Common Top & Bottom Construction for a Shaker Baghouse
Top Load Baghouse: Grommet Top, Loop Top, Strap Top Bottom Load Baghouse: Corded Cuff Bottom, Double Beaded Snap Band
If you would like to get a free media recommendation, check out our filter bag media quiz here. There is also a fabric characteristics sheet that you can download below. It takes a closer look at the most common filter bag medias used in the dust collection industry.
Filter bag configurations can vary from one dust collector to another. Baghouse filter top and bottom configurations will be dependent on the type of baghouse dust collector you have. The most common types of baghouses are pulse-jet and plenum pulse, reverse air, and shaker.
Pulse-Jet and Plenum Pulse Baghouse
Pulse-jet and Plenum Pulse baghouses collect dust on the outside of the filter. Dust-laden gas floods the dust collector, and clean air exits through the inside of the bag while dust particles collect on the outside filter surface. A pulse-jet is one of the most common styles of baghouses will see across a variety of industries and applications. The most common types of filter top and bottom configurations in this style of baghouse are:
Top Load Baghouse Filter: Double Beaded Snap Band Top, Disc Bottom Bottom Load Baghouse Filter: Raw Top, Disc Bottom
Reverse Air Baghouse
In reverse air baghouses dust will collect on the inside surface of the filter. Air enters the dirty side (inlet) of the baghouse and flows upwards through the bag. The bag filters and collects the dust on the inside, then clean air exits through the top of the bag. Reverse air baghouses are typically seen in large air handling applications like energy.
Top Configuration: Compression Band with Cap & Hook Bottom Configuration: Compression Band, Corded, Double Beaded Snap Band
The way shaker baghouses collect dust is similar to reverse air baghouses. Dust is collected on the inside of surface of the filter. Dust particulate is filtered and collected on the inside of the filter, then clean air exits through the top of the bag. The difference in this system is in how the bags are cleaned. Filter bags are hung and tensioned from the top of the unit, and at the bottom they are attached to a tube sheet. As the name suggests, you clean the bags by mechanically shaking them. Shaker baghouses are generally simple, and can be seen in applications where there is no compressed air available.
Top Configuration: Grommet Top, Loop Top, Strap Top Bottom Configuration: Corded Cuff Bottom, Double Beaded Snap Band
Filter bag construction and dimensions vary between industries, applications, dust collector types and manufacturers. Here are some of the filter bag top and bottom configurations you may come across.
Hi, this is Bob with US air filtration. And today I’m going to show you how to change out the diaphragm inside a solenoid pulse valve.
Pulse Valve Types
As you can see here pulse valves come in a lot of different sizes and shapes. Some valves have coils on the top, and some don’t. Pulse valves can have two diaphragms or one. Others have couplings, threads, or flange connectors. But the process of changing out the diaphragm is really very similar in all of them.
First Steps to Replacing a Diaphragm Valve
I’m going to show you today, on this particular valve, how to change out the diaphragm.
First thing that we’re going to do is remove the bolts that are holding on the top of the belt. I’m using a socket set and I’m going to loosen these up. Once I get all the valves loose I can pull off the top.
I’ll tell you, sometimes when these valves have been sitting, especially out in the sun for a while getting this top piece off isn’t really easy. You may need to take a screwdriver and a hammer and just tap it lightly there where the rubber is to help get the top off.
But once you get the top off you can remove the spring and you can peel off the diaphragm.
Diaphragm Valve Bleed Hole / Pin
Now in some pulse valves, well in all pulse valves, there’s a little bleed hole. And often times, there’s a pin this particular one, has a little pin right here that this allows the air pressure to equalize between the two halves of the valve.
It’s really important that we don’t block this hole or damage this pin when we put the valve back together.
Once we pull off the old diaphragm kit, we can grab the new diaphragm. And the first thing we want to do is find out where that bleed hole is in the diaphragm. Here, it’s this hole right here. We’re gonna place that right over the pin.
The teflon disc or it’s a rubber disc on your diaphragm goes down so that it seats up against this part of the valve. It’s not a bad idea to look and make sure that there’s no damage to the the body of the valve.
Typically though these aluminum bodies; it’s really hard to damage them. I don’t usually see problems with them. It’s usually the diaphragms that go.
We’re gonna line up the hole with the bleed hole. And make sure our holes line up and put our diaphragm back then.
Then we need to make sure that we have the spring that comes with the repair kit that goes back on top of the diaphragm and then we’re gonna put the top back on.
Now just like I mentioned, with this bleed hole, there’s a place where the bleed hole on this top cover goes. We need to make sure we’ve lined that bleed hole up with the bleed hole here.
If we block it, the valve is not gonna work. Or if you don’t put it on correctly, and there’s a pin, you’ll squash the pin. And then you’re gonna have to buy a new valve just to replace this little pin.
We’re gonna line this up. And I can kind of feel it set on the right. And then we’re just going to tighten down all the bolts.
Now once I get everything finger tightened I want to go ahead and tighten these bolts down.
If I don’t tighten the bolts down properly, and you don’t get this clamping this diaphragm together, you’re gonna get a leak outside of the valve.
The best practice is, with your ratchet, is to tighten the bolt on one side and then go to the opposite side and tighten it down. And then just keep going about 180 degrees so that your getting a nice even pressure.
Upper Smaller Diaphragm
Okay now we need to do the little diaphragm.
I’m gonna pull off this coil, which I could have done before. And actually if you have electrical wires connected to this, it helps to pull off the coil.
I might add too, before you start this you need to turn off the compressed air to your valve. Or as soon as you start releasing this, it’ll just start blowing everywhere
Okay. So to change out this upper smaller diaphragm we need to loosen up these four bolts here with an allen wrench.
I’m going to loosen all of these up and then remove these bolts.
Okay once all the bolts are loose, you can lift off the top. Once again, there’s a spring and the diaphragm. You’ll grab the new diaphragm with the little metal side down.
Again there’s a little tiny pin right there for the bleed hole. Every diaphragm is gonna have a bleed hole somewhere that you need to make sure you line up.
There are a few types of valves that the bleed hole is actually in the body of the diaphragm.
In those cases you don’t have to worry about it too much. But a lot of valves have these pins.
So, I’m gonna line this bleed hole up and put it on. And take the new spring and put it on. And then I’m going to make sure that my hole right under here, where the bleed hole goes, is gonna go right over that bleed hole.
I can feel it seat down on there. And again I’m gonna tighten the bolts.
Everything’s good and tight. Put our coil back on.
And now we’re ready to turn the compressed air back on, and test our valve to make sure it all works.
Are you spending too much time and money on costly change-outs?
Would you like save yourself from the headaches that come with change-outs? Then PTFE may be the answer to your problem. Our brief video guide will provide some information on how PTFE membrane works and its benefits when its added to your filter media.
Hi this is Bob from US Air Filtration.
Do you want to get twice the life out of your filter bags and reduce costly change-outs?
What if your dust collection system captured more dust?
Would you like to get consistent airflow or suction through your dust collection system while reducing wear and tear and reducing maintenance costs?
If the answer to any of these questions is yes, then PTFE membrane filter bags may be the answer. For you to understand how PTFE membrane bags can accomplish these things let’s first look at how a standard filter bag works.
How a Standard Filter Bag Works
On a standard bag dust builds up on the outside of the bag and creates what is known as the filter cake. The filter cake actually does the filtering while the bag fabric acts only as a support for the cake. When the bags are pulsed most of the filter cake releases and the build-up of dust begins again.
Over time however, some of the dust gets embedded deep into the bag fibers. Eventually, the bags will completely plug and need to be replaced.
Adding PTFE to a Filter Bag
Conversely, when PTFE is added to the bag it acts as the filter cake. Commonly known as Teflon. PTFE is used in many different applications from cookware to outerwear and more. When a PTFE membrane is laminated to a filter bag media it can enhance the performance of both the filter bag and the dust collection system.
How PTFE Membrane Works
Let’s take a closer look at how a PTFE membrane works. If we zoom in on the PTFE membrane we can see that it is actually made out of tiny microscopic holes like Swiss cheese. The holes are large enough to allow air molecules and vapors to pass through but small enough to inhibit even the smallest dust particles from getting through.
Because the membrane keeps the dust on the surface of the bag particles never get embedded in the bag fibers and the bags will not fail from plugging up. Typically PTFE membrane bags wear out before they plug up. Usually lasting twice as long as standard bag.
Benefits of PTFE Membrane
With twice the lifespan costly change-outs and plant shutdowns are cut in half reducing maintenance costs and increasing plant production. Since the bags are not gradually plugging up over time, PTFE bags give the additional benefit of providing more consistent airflow or suction from your dust collection system.
Because of the small pore size, PTFE membrane bags are up to eight times more efficient than a standard filter bag. This means it can cut out dust collector emissions by up to 800 percent.
Additional Advantages of PTFE Membrane
Another advantage of PTFE membrane bags is that they clean easier because of their slick surface. This means less bag pulsing. Which also means less wear and tear on the bags as well as the diaphragms and solenoid valves. It also means the system uses less compressed air resulting in reduced energy costs.
It can also improve performance when higher moisture levels or sticky dust are present. PTFE membrane can be added to any bag media and can replace standard bags and almost all applications. While there is a cost to add the membrane, the extra cost easily pays for itself. It provides longer life, reduced maintenance cost, reduced wear and tear, and lower emissions.
To find out if PTFE membrane filter bags are right for you call and talk to one of our experts today.
Your dust collector is a major investment. Maintaining your system’s vital components is going to play a critical role in keeping your production down time and maintenance costs to a minimum. To help you determine if your filters are compromised and it’s time for a dust collector change out, check out our brief video below.
Are you ready to change out your dust collector? Download this check list below.
Hi, I’m Bob from U.S. Air Filtration. Today, I would like to answer a common question that we are often asked. That is, “When is it time to change my filters?”
There are several key indicators and considerations that will help you determine the answer to this question.
Before we discuss these, let’s review the two main reasons for changing filters. One, either the filter fabric has become compromised by a hole or tear in the fabric which now allows dust to pass through. Or two, the filter fabric has become fully entrained or clogged with dust particles which permanently restrict air flow through the filters.
Dust Collector Change Out Indicators
Ok, Let’s talk about the indicators:
This may seem obvious, but the first indicator is if you see dust coming out of the clean side of the collector. This means you likely have either a hole in the filter or the filter’s seal has been compromised.
You can find bad filters by conducting a visual inspection. Sometimes the holes may be very small or hard to find. In these situations, you can find the leak by conducting a leak test.
This is accomplished by introducing leak powder into the system. The powder will concentrate around any leaks and become visible under a black light. Call us to learn more how this product works.
While damaged filters with holes or a poor seal will leak dust, clogged filters do not leak dust. Instead the dust becomes embedded into the fibers of the filter. This increases the resistance of the air flow, which increases the differential pressure reading on your dust collector.
Differential Pressure is the difference in air pressure between the clean and dirty sides of a collector.
A consistently higher differential pressure indicates that it is more difficult for the air to get through the filter media and usually means filters are nearing the end of their life span.
When you consistently see Differential pressure readings of 6 or above and they don’t drop significantly during the collectors cleaning cycle, it’s generally a sign that it’s time to change your filters.
Loss of Suction at Pick Up Points
Another indicator that points toward a filter change-out is when your pick up points are not getting the suction you’re used to seeing. It is the permanently entrained dust that causes the reduced air flow, and as we mentioned, the higher differential pressure.
Dust Collector Change Out General Rules
Let’s discuss a few other considerations.
As a general rule, it is better to change out all the filters in a collector than a few at a time. Air flow always follows the path of least resistance, and you can quickly wear out new filters if they are doing all the work in your collector.
Some of our clients like to change out filters during scheduled plant shut downs or on a maintenance schedule.
Filters may have some life left, but this is a good option if the risk of having a problem before a scheduled shut down is too great, or the predictability of filter life is fairly certain.
One final thing to consider is using a laboratory test to determine how much life remains in a set a filters. This testing is not common and is typically only when the bag cost is substantial and there is a lack of history with the bag life or there is some other unique problem that can’t be otherwise solved. In most cases, the other mentioned indicators are sufficient to determine when to change out your filters.
How Long Filters Last
Another question we are often asked is how long do filters typically last.
This is a really tough question to answer because there are so many environmental factors that come in to play. We have seen filters last anywhere from a few weeks up to 5 years or more. On average, life expectancy is about a year, but it really varies.
Here is a list of some of the factors that influence filter life. To find out more about these factors or to ask one of our experts if it’s the right time for a dust collector change out, give us a call.
The right baghouse dust removal method can help minimize problems that arise due to dust build up in your hopper.
A hopper is designed to be temporary storage for your discharge. What happens if you have excessive dust build up in your hopper? This can result in your air flow being blocked off and would cause a loss of suction throughout the dust collection system. This can also become a hazard because it’s more opportunity for combustible dusts to create a dangerous explosion. The right dust removal method for your application can help you avoid these issues.
The best method of dust removal from your hopper is dependent on some of the following components:
What are the characteristics of your dust? For example, hazardous or non-hazardous?
What are the loading rates of your dust?
Baghouse Dust Removal Methods
A simple pipe system funneling dust into an enclosed box, placed underneath your hopper, is one dust removal option. Your maintenance team would be required to monitor and empty the box once capacity has been reached. Prompt removal of dust build up in your enclosed box helps prevent backup or an overflow of the box itself. Non hazardous dust and light dust loads typically use enclosed boxes.
Drum or Bag
A removable drum or bag can be a simple and easy solution to collecting and disposing dust. Once a drum or bag fills up, maintenance simply removes it by hand or forklift. Once empty, the drum or bag can then be put back into its place. This is ideal for non toxic dusts that you can easily handle.
Rotary valves (also known as airlocks, rotary feeders, or airlock feeders) help transition material from a dust collector to a drum or bin. It seals a pressurized system against loss of air and pressure. This minimizes product loss during processing. Dust collection, pneumatic conveying, mixing, weighing, feeding, and blending use rotary valves. Larger baghouse systems with over 10,000 CFM can also use rotary valves.
Screw Conveyor for Baghouse Dust Collectors
Large baghouses with heavy dust loads typically use screw conveyors. The screw conveyer would transport dust away from the collector, then send it to a designated disposal area. This is ideal for hazardous or reused materials. Agriculture, mining, foundries, wood production, and chemicals are applications that use screw conveyors.
When it comes down to finding the right dust collection system, there are a few different baghouse styles to choose from. So how do you know which one is best for you?
Before we dig into the differences between some of the baghouse styles, you need to consider your dust properties and air-to-cloth ratio. Baghouses are ideally suited for large volume applications with airflow exceeding 1,000 CFM or when high temperature applications are above 375 degrees. In these environments, a baghouse will handle and most efficiently filter your dust laden air.
There are three main baghouses styles (e.g. shaker, reverse, and pulse-jet) that are commonly used in most industrial processing and manufacturing applications. Here’s a brief overview on the pros and cons of each to help guide you in identifying the right option for your work environment.
Pulse Jet Baghouse
Constantly cleaned so there is minimal dust build up in the dust collector
Requires dry compressed air
Cannot be used when there is humidity of high moisture content present
Requires fewer bags
Cannot handle high temperatures (unless you use special filter media
Do you have a new dust collector project in the works and need help determining the volume? Our introduction to dust collector volume can help with that.
The Right Volume
The most important consideration to factor into a new dust collector is making sure the airflow or volume of the dust collector is efficient at capturing dust and is right for your application.
For instance, if the volume of your system is too low then your system will not filter dust as efficiently. As a result, your production, air quality and life of your collector can be shortened. Similarly, if it is too high then your energy consumption costs can be higher and you could disrupt the process of your application.
Measurement of Volume
You measure volume in cubic feet per minute or otherwise known as CFM. CFM is a measurement of airflow related to air conditioning, heating and ventilation environments. In dust collector applications CFM measures the amount of air per minute that can be moved from a space.
Work environments vary dramatically from one another based on several variables. Even very similar environments can require vastly different volumes. To determine the right capabilities for a new dust collector, here are some variables to consider carefully.
How are you collecting your dust?
What is the size of your duct being used to collect the dust?
What is the cubic feet of your work environment?
Calculating volume for new installations.
Do you need more detailed information? Download our full guide to dust collector volume below. In addition, it comes with a chart that can be helpful for your new dust collector project.
A well maintained dust collector ensures your system is performing at peak efficiency. It’s also critical to minimizing unscheduled plant downtime and the wear and tear of your dust collector parts. As part of a regular preventative maintenance program, customers can also request a visit from bonded and insured technicians to perform either a dust collector inspection. An inspection typically includes an analysis of your dust collector and its most vital parts, a written report, and recommended corrective actions to solve any issues. An inspection may also include an exam of the following:
Overall status of dust collector(s)
Compressed air system for leaks
Air Shut off valve is sealed and is properly working
Repair or replace damaged solenoids, valves, or diaphragm kits
Any other repairs or troubleshooting needed on a baghouse – for example, vibration issues with a system after a filter change
Dust Collector Inspection and Service Questions
If you are looking for an inspection or service from a supplier, here are some of the most common questions asked before receiving a formal proposal and costs.
What type of service or troubleshooting are you requesting?
Where will the service take place?
What type of dust are you filtering? Is it hazardous? Is special safety equipment required?
Are there any current issues with your filters?
Is there any special training or background checks needed before entering a facility?
When would you like to have the service performed? What are the permitted service hours (evening or day work, weekends only, etc.)?
For more information on inspections or services for your dust collector, you can contact a USAF account manager at 888-221-0312 or also email [email protected] Also included below is a link to our comprehensive dust collector maintenance eBook that can be downloaded.
Pulse-jet filter bags are used to remove dust particulate and contaminants from the air in warehouses, plants, factories, foundries, and more. Pulse-jet is one of the most common styles of baghouses you will see across a variety of industries and applications. With this style of baghouse, dust collects on the outside of the filter as clean air exits through the inside of the bag.
How Pulse-Jet Filter Bags are Cleaned
To clean pulse-jet baghouse filters, a blast of compressed air is injected through a blowpipe over each row of bags via a venturi. In a pulse-jet baghouse one row of bags can be cleaned while the remaining rows continue to collect dust particulate. This is known as on-line cleaning.
Construction of Pulse-Jet Filter Bags
Pulse-Jet baghouses are engineered to hold either bottom or top load filter bags and cages. Fabric filter bags used in pulse-jet and plenum pulse baghouses come in a variety of medias and treatments. The type of filter media and treatment that’s best will be dependent on a plant’s application and dust characteristics. To get a free filter recommendation, check out our filter bag media quiz here. You can also download our fabric characteristics sheet to get a closer look at the most common filter bag medias used in the dust collection industry.
Most Common Top & Bottom Construction for a Pulse-Jet Baghouse
Top Load Baghouse: Double Beaded Snap Band Top, Disc Bottom Bottom Load Baghouse: Raw Top, Disc Bottom