Entries by Dominick DalSanto

¿Qué es un filtro HEPA secundario y cuándo necesito uno?

In the search for cleaner indoor air, many industries face the challenge of maintaining optimal air quality within their facilities. One effective solution is incorporating a dust collection system equipped with a High Efficiency Particulate Air (HEPA) after-filter. Let’s review some of the most frequent questions regarding this type of filter.

HEPA filter at industrial facilities
Positioned on the clean air side of the unit, the HEPA after-filter acts as a secondary filtration stage, capturing even the tiniest microscopic particles before the air is returned to the facility.



Buy an HEPA Filter

 

Question: How Is a HEPA filter made?

Answer: HEPA filters are made from polyester, polypropylene, or fiberglass fibers that are tightly interlaced with diameters of less than one micron. The fibers are twisted, turned, scattered, and randomly placed in different directions to create a mesh maze without a straight through path. The openings between the fibers are smaller than a half micron, which is why HEPA filters can catch particles smaller than 0.3 microns.

Question: How Does a HEPA After-Filter Work?

Answer: When a dust collector draws in dirty air and dust particles, the primary filters capture larger particles while allowing cleaner air to pass through. However, ultrafine particulates may still escape through the primary filters. Here’s where the HEPA after-filter comes into play. Positioned on the clean air side of the unit, the HEPA after-filter acts as a secondary filtration stage, capturing even the tiniest microscopic particles before the air is returned to the facility.

Inside a HEPA filter
HEPA filters are made from polyester, polypropylene, or fiberglass fibers that are tightly interlaced with diameters of less than one micron



Buy an HEPA Filter

Question: How is a HEPA filter different from regular filters?

Answer: The main difference between a HEPA filter is that it is made of thin fibers of glass and activated carbon-based materials. Regular filters are made of porous materials like cotton, paper sheets or polyester. Most importantly, HEPA filters offer much higher filtration efficiency (MERV 16 or higher) compared to a standard fabric filter.

Question: ¿Cuándo necesito un filtro HEPA?

Answer: Considera incorporar un filtro HEPA posterior en los siguientes escenarios:

  • — Si tu proceso genera partículas finas que representan riesgos para la salud o pueden contaminar productos.
  • — Cuando las normativas o los estándares industriales exigen una calidad de aire excepcionalmente alta.
  • — Si el polvo recolectado contiene materiales peligrosos, alérgenos o carcinógenos.
  • — Cuando se busca recircular aire filtrado de vuelta a la instalación, lo que requiere aire más limpio para mejorar la calidad del aire interior.

Question: Does a HEPA After-Filter Help Against COVID-19?

Answer: Yes. By incorporating a HEPA after-filter into your dust collection system, you can significantly reduce the risk of airborne transmission of the virus within your facility. While other safety measures like social distancing and mask-wearing are essential, purifying the air with a HEPA filter adds an extra layer of protection.

Different stages of a HEPA after filter
HEPA after-filter serves as a powerful ally when searching for cleaner indoor air quality, particularly in industrial settings

 

Question: What Does it Cost to Add a HEPA After-Filter?

Answer: First, the size and quantity of HEPA filters for your system will depend on the airflow of your system. Each HEPA filter is sized for a specific airflow, and multiple filters may be required to meet the required airflow and static pressure requirements of your system. Once the quantity, size, and type of HEPA filter is determined, a HEPA filter housing is needed to house the filters, along with ductwork to connect your HEPA filters to your existing dust collection system, and route clean air to the desired location. A Baghouse.com dust collection specialist can help you size and spec out a HEPA after-filter and provide a quote for your project.

 

In conclusion, a HEPA after-filter serves as a powerful ally in the ongoing battle for cleaner indoor air quality, particularly in industrial settings. Baghouse.com can provide expert guidance in selecting the right HEPA filter and offer comprehensive support from installation to maintenance. 

 



Buy an HEPA Filter

Do you have any additional questions regarding the HEPA filters? Contact us today to discover how we can enhance your dust collection system with HEPA filtration.

 

Habla con uno de nuestros expertos en recolectores de polvo


Para obtener más capacitación e información relacionada con colectores de polvo, visita también nuestra página de Baghouse Training haciendo click aquí.

/by
, ,

¿Por qué algunos filtros son más caros que otros?

¿Por qué algunos filtros son más caros que otros?

Baghouse.com sells a lot of filters each year, including thousands of bag filters and cartridge filters in the most common configurations as well as just about every type of unusual or obsolete filters that are still found in baghouses around the country.

While we are one of the most experienced companies in the industry, with a huge network of filter fabrication shops and the economies of scale that come with large volume manufacturing, our filter prices are not always the cheapest – why not?

The answer comes down to two factors: filter design and filter quality.

Filter Design: The Right Filter for the Application

Filter and cages

Los filtros para colectores se utilizan en una enorme variedad de industrias y aplicaciones.

Baghouse filters are used in a dizzying range of industries and applications, from nut processing to aerospace manufacturing to battery recycling to silica mining. Every application has a specific dust type, air temperature, air flow and velocity, dust content, and chemical profile that must be understood to properly identify the correct filter media for the application. To further complicate matters, just about every dust collector manufacturer designs their equipment to use a very specific filter size and configuration – from shaker filters with hangers, to top-load baghouses with snap-bands and cages, to bottom-load baghouses with thimbles and band clamps. The variables are virtually endless.

The cost of your filters of the lifetime of a dust collector depends on having the correct filters installed. Use the wrong filter media and the filters will be damaged quicker – the wrong configuration or size and they will leak, requiring replacement sooner.

Some filter designs are less expensive than others – a standard top-load bag filter made from 16-ounce polyester fabric is produced in large volumes and is thus less costly than a specialty fabric (Aramid, for example). However, if your gas temperature spikes higher than 275 degrees F. Using the wrong filter will result in an early failure and the cost of a new set of bags.

 

Summary: Selecting the correct filter design will result in the lowest total cost of filters in the long run.

Filter Quality: Risks of Selecting the Lowest Bidder

Assuming you have selected the correct filter media, filter configuration, and size, your purchasing decision should just be to select the lowest price offer right? Not so fast – just like some car manufacturers offer better quality than others, not all filter makers are equal. The biggest differentiator is quality.

Baghouse.com personnel recently evaluated a dust collection system at a new customer. The customer wanted to know why their filters had failed prematurely. The baghouse was processing gypsum dust with a very fine particle size requiring a PTFE membrane, used for high-efficiency filtration of fine dust. However, shortly after installing the filters, the customer noticed that their emission limits were well over their permitted limit.

Microscope image of bag filter

Microscope view of this filter shows PTFE (white) was sprayed on, not applied via a membrane.

 

Baghouse.com sent a filter sample to the lab and discovered that, instead of a PTFE filter membrane, the filter manufacturer had sprayed on a PTFE layer which left large gaps in the PTFE coverage of the filters, allowing dust to pass through and into the atmosphere. The purchasing specialist at this customer had chosen these filters due to the lowest quoted price, but the result was the purchase of a new set of higher-quality filters, much sooner than anticipated.

Summary: Focus on long-term cost, not just the lowest price tag.

Expertise & Quality

En Baghouse.com, our mission is to be the most trusted name in dust collection. That means that we never offer a sub-par product, either an improperly designed filter or a low-quality filter, to win business from our competitors.

With our 40 years in the industry, our team of experts will ensure that any filter we sell is the correct design for your application. Additionally, the filters we sell are the highest quality and made in the USA. We expect our customer relationships to last a lifetime, not just until we get a PO in hand. We may not always be the lowest bidder, but we strive to offer the most long-term value for our customers.

Have More Filter Questions? Contact Us to Speak to One of Our Baghouse Experts.



Contact us now

/by

Other Causes of Baghouse Filter Failure

The four main reasons why baghouse filters fail prematurely are abrasion, exceeding the maximum operating temperature, chemical attack and fire. All of these can dramatically shorten the the life of a baghouse filter as well as cause serious damage to the baghouse system*. However there are other lesser known causes that can cause premature dust collector filter failure. Let’s review them.

“If the filter system is undersized, then the filters will suffer increased wear…”

Colector de polvo subdimensionado para el flujo de aire (CFM)

It is essential that an industrial baghouse system be carefully engineered and sized to handle the right amount of air flow (CFM) for the application. If the filter system is undersized, then the filters will suffer increased wear.  Additionally, an undersized system will eventually lead to inadequate air flow, poor venting that can damage equipment, higher emissions, loss of reclaimed product and a hazardous work environment.

A dust collector can be undersized in two main ways: (1) by not having enough filters for the airflow, and (2) by having too much airflow through too small of a unit, thus creating high internal can/interstitial velocity.

Sadly, many less reputable sales reps and even some dust collector OEMs often undersize systems in order to undercut their competition on price. Other times, plants have tried to increase system capacity without consulting with an experienced dust collector manufacturer and even up overloading their units.

Filtro incorrecto (material o estilo)  

The choice of baghouse filter media depends on a number of factors, such as temperature, resistance to chemicals, target dust size, physical characteristics, collection efficiency and price. If the choice of fabric is unsuitable for the application required, this can have a dramatic reduction in the lifespan of the filter.

For example, trying to use a low temperature filter fabric such as polyester (max temp 250F – 275F) in a high temperature (300F – 500F) baghouse system will quickly result in filter failure. 

Often, operators must consider more than just the maximum temperature as the mix of temperature, humidity and chemical makeup in the gas stream can cause failures if not accounted for when selecting the media. For example, in many gypsum applications the temperature is not normally very high (under 200F) so polyester media might seem to be a good choice. However, the combination of elevated temperatures and high humidity can cause the gypsum to react with the polyester and cause hydrolysis, which leads to the bag becoming hard and brittle. For this reason many gypsum applications used aramid filters even though the temperature normally would allow for cheaper polyester bags.  

Finally, many suffer problems due to using cartridge filters where a bag filter is more appropriate. Man applications can make good use of cartridge collectors to improve operation and reduce the overall cost of a system. However, we often see people try to use cartridges in applications ill-suited for them such those with irregular-shaped material, sticky materials, or high temps.

 

An image of a baghouse filter that has hardened from hydrolysis
Picking the right fabric for the right temperature isn’t everything. This is the effect of hydrolysis on an improperly selected baghouse filter.

Jaulas dobladas o dañadas

During regular maintenance or when stored improperly, cages can be bent, damaged, warped and or even corroded. Using baghouse filter cages in this condition will lead to the filters failing prematurely. When a cage is bent or damaged, sharp points can form from broken wires and cracked welds that can physically damage the filter creating tears and holes.  If rust or corrosion is present on the cage, this creates abrasion and leads to tears and holes in the filter. Additionally, bent cages will cause the bags to hit each other or the sides of the housing when they are pulsed creating localized wear spots.

An image of a PTFE filter with two small holes in its fabric
Have you reused rusted or bent baghouse filter cages and then seen holes in your filters like these?

Mala instalación

Improper installation of filter bags can also result in early bag failure and loss of cleaning effectiveness. For top load pulse jets, the most common install errors involve not seating the snap band properly. For a bottom load unit the bag not being folded over the top of the cage properly, poor clamp placement and tightening the clamp too much or too little are all common. 

Additionally, duct design, turning vanes and deflection plates all contribute to uniform gas distribution to all filters. However poor installation of these elements can result in high airflow regions that will abrade the filter bags.  Rough handling such as bending or stepping on the bags during installation or improper tensioning can also cause holes or tears in the bag filters reducing their strength and durability.

Humedad

An image of dust collection filters completely covered in build-up from moisture
Please tell us that you check your baghouse filters enough before letting moisture build up this badly.

Common sources of condensation and moisture in a baghouse are leaking gaskets around the doors and airlocks or upset conditions in the process.  Moisture can weaken the filter media, causing filter leaks or failures, and allow dust to bypass the filters. It can also alter the adhesion characteristics of the dust creating hard-to-clean mud and blinding of the filter. Moisture can also create chemical issues within the baghouse. For example, acid gases mixed with high moisture can cause an acid flash. This is where the acids condense out of the gas stream and damage the filters and housing. 

As discussed in this and the previous article, there are a number of reasons why industrial baghouse filters fail prematurely. Baghouse.com has experience helping many with these and other problems find solutions to get their systems back to peak performance. For more information and to arrange a quote for all your baghouse requirements, please contact us at Baghouse.com

* See article “Top 4 reasons why baghouse filters fail”

 

Need Help Ordering Baghouse Filters?

Whether you know exactly what you want or could use some help getting the right dust collection filter, we’ll put together a free quote with the perfect filter for you.

 



¡Habla con un experto!

/by

Video: Guía para calcular y diseñar tu colector de polvo

 
Esta es una introducción a la Guía de Baghouse.com para calcular y diseñar tu sistema de recolección de polvo. ¡Esperamos que te resulte muy práctica!

Es un gusto poder presentar nuestra Guía sobre cómo calcular y diseñar correctamente tu sistema de recolección de polvo.

Esta guía te ayudará a evitar algunos de los errores más comunes que vemos al dimensionar un sistema de recolección de polvo. Por ejemplo, muchos fabricantes de colectores de polvo y revendedores suelen subdimensionar sus sistemas para ofrecer el precio más bajo en una licitación. Sin embargo, una vez instalado, el sistema no funciona adecuadamente.

Nuestra guía te ayudará a calcular el tamaño aproximado y a determinar una configuración de sistema que satisfaga las necesidades de tu aplicación y sus respectivos procesos, lo cual podrás usar al comparar cotizaciones de diferentes fabricantes. Además, nuestra guía proporciona información útil para el mantenimiento general del colector de polvo, su operación y los procedimientos de seguridad asociados.

Si tienes alguna pregunta, no dudes en contactarnos para obtener más información.

/by

¿Cuál es el mejor método de descarga para la tolva del colector de polvo?

Dominick DalSanto Director of Operations | Dust Collection Specialist | Industrial Filtration Consultant Dominick DalSanto is an author and environmental technologies expert specializing in dust collection systems. He has nearly a decade of hands-on working experience in the industry. Dominick is the sales director and sales technical advisor for an industrial dust collection equipment manufacturer. […]

/by

Additional Considerations for Dust Collection System Design (Part 4 of Design Guide)

In this design guide we have reviewed a relatively simple baghouse dust collection system with few variables. Even at this level it is still recommend to consult with an experienced dust collector OEM like Baghouse.com before making any equipment purchase. There may be additional factors to consider before determining the final sizing, design, construction and installation of a dust collection system.

Common Additional Considerations

  • Recirculating air back into facility
  • Balancing system with blast gates
  • Combustible and toxic dust
  • Filter styles
  • Dust discharge (manual or automatic)
  • Option for VRD fans

Recirculating Air Back Into The Facility

Recirculating air from the dust collector exhaust can prove practical in areas with cold climates to conserve heat. Make sure to include a ambient air return line to balance the airflows and prevent carbon monoxide poisoning. Additionally, any return duct needs to be sizes at least 2 inches larger than the main duct entrance and its SP added to the system total. Additionally, OSHA and other applicable safety regulatory bodies require any recirculated air to pass through a HEPA after filter.



Combustible Dust and/or Toxic Compounds Hazards

Many types of dust, including many woods are toxic, so take special care to choose a filtering system that will provide optimal safety. Facilities that handle combustible dusts must take special precautions to avoid potentially serious safety hazards from forming within their dust collection system. The National Fire Code issued by the NFPA (National Fire Protection Agency), OSHA combustible dust emphasis program, and the OSHA General Duty Clause and many other similar local and state regulations now require a combination of explosion/fire prevention and/or protection devices for any dust collection system handling combustible dusts. Prevention devices include spark arrestors, abort gates, high-speed sprinklers, inert gas or injection systems, and more. Protection devices include explosion vents, high-speed sprinklers and dry extinguishing injection systems. Fire experts should be consulted for any system potentially handling combustible dusts.

Filter Styles

Pleated Filters - Top and Bottom Load

New filter styles such as pleated filter elements can improve operation, reliability and collection efficiency while also lower operating costs (less compressed air to clean, last longer) compared to traditional bag and cage technology. They also allow for much smaller units (thus cheaper to build) while still having better air to cloth ratios compared to bags since they also provide more filter cloth in a smaller area.

Bags, cartridges or pleated filter elements are three common filter styles used in baghouse dust collectors. Cartridges are rarely used in new systems except for a handful of OEMs due to high cost and difficulty sourcing replacements. Bags and cages are the most versatile being able to work in the widest range of applications including temperatures up to 500F. In newer systems, pleated filter elements (sometimes called pleated filters) provide a much larger filter cloth area in a smaller space compared to bags (usually 3 times as much filter in half the space). They are widely manufactured and are only marginally more expensive than bag and cages. In addition, they provide superior performance, require less cleaning energy (i.e. compressed air) and provide less pressure drop over a longer service life. And due to their smaller size, collector units can be made smaller. (See our case study showing benefits of converting from bag/cage technology to pleated filter elements)

Best Practices to Increase efficiency and Reduce Size

Try to capture dust as close as possible to source to reduce size requirements. More directed venting better solution than venting large area as volumes increase rapidly when venting entire spaces e.g. Venting one machine at 600 CFM = 6 bag unit vs. venting entire room of 30’ x 30’ x 10’ = 9,000 cubic feet of air = 125 bag unit @ 3:1 ratio Oversizing for future expansion Good idea to size in additional 10% capacity for later. Minimal added costs upfront to add additional capacity, resizing later much more expensive (10:1 ratio roughly)

Balancing System Using Blast Gates

Blast gates should be installed on all branch lines to maintain system balance. Their proper use should also be part of regular training for dust collector operation.

Clean Out Traps

If your system has areas where long slivers of material could possibly hang-up and cause a clog, install a clean-out near that area.

Determining Required Capacity For Secondary Sources

6 baghouse hopper dust discharge styles

Various options exist for disposing of dust from the baghouse hopper. Here are 6 discharge methods

After adding all primary lines together determine how much extra capacity you want to install for secondary lines. If secondary branches are run sparingly then its possible to not include them in the calculation. When they need to be used you can divert some of the capacity from the primary branches (by shutting them down and blocking those ducts using a damper valve). Be realistic when calculating your needs and size appropriately.

Consider Variable Frequency Drive (VFD) Fans

VFD fans allow for more control over system performance and potential energy savings when loads constantly change.

Dust Discharge Options

The most basic discharge is a manual slide gate, that is activated manually by personnel. If dust loads are light or the system is infrequently used this may be the most economical option. However, failure to keep the baghouse hopper clean and result in major operational problems and damage the filters. Another option is for a rotary airlock that automatically cleans the hopper. This eliminates the need for a technician to manually clean the hopper, but comes at a price tag in the $2,000 – $3,000 range.

Ready To Size Your Dust Collection System?

Thank you for reading our online guide to sizing your dust collection system. After considering this information should be able to estimate what size dust collection system your facility needs. With this information in hand you can begin the bidding process for your new system. Baghouse.com experts are ready to help if you have any questions. Please feel free to call at (702) 848-3990, contact us via our online form, or visit our resources section for more helpful dust collector information.

Need Help Designing Your Baghouse System?

Looking for help designing your dust collection system? Let our us use our 40+ years of expertise to help you select the right system for your application.
[/av_promobox]

 Guía de diseño de sistemas de baghouse

/by

Design Process for Your Baghouse Dust Collection System (Part 3 of Design Guide)

We continue from our last article where we reviewed the 4 key design variables of airflow (in CFM), static pressure/resistance, air velocity and air to cloth ratio. Now we can begin calculating these variables for our new dust collection system. When we are finished we will know exactly how large of a baghouse we will need (including how much filter area required) along with our fan output (x airflow @ y static pressure).

The sizing and design process can be divided into two stages. The first stage involves sizing your duct work for adequate volume (CFM) and velocity (ft/m) for the type of dust you will be handling. Then in the second phase you calculate the static pressure (SP) of your system to determine the size of your baghouse (how many filters and what size) and power of your system fan. If you already have a ductwork system and want simply to replace an existing baghouse/fan combo, you still need to calculate the CFM and static resistance from the existing ductwork system to properly size the baghouse and/or fan.

Step 1 – Find the Minimum Conveying Velocity (ft/m) of Your Product

Determine from a reputable source the minimum conveying velocity for the material the system will handle. The box on the right lists several common materials and their recommend conveying velocities. Most materials require between 3,500 ft/m to 5,000 ft/m. A more extensive list can be found on Baghouse.com

Step 2 – Identify Total Number of Primary and Secondary Sources

Sizing your system requires you to determine how many much airflow you need at each location. Begin by making a list of all the equipment you plan to vent with the dust collection system. Identify your primary and secondary sources that you will connect to the system.

Primary Sources need constant venting whenever system is running. Some facilities may have only one large source to vent (e.g. a single boiler, furnace, etc.). Others may have many different systems but each one requires its own system as the different equipment cannot be connected for some reason (e.g. gypsum plants, cement plants, process applications)

Secondary Sources do not always run concurrently without primary sources and sometimes shutdown completely. Secondary sources are common in wood/metal milling, fabrication and manufacturing shops. For example, a woodworking shop uses several different pieces of equipment such as saws, lathes and sanders requiring dust collection. While the large saw and lathe run continuously everyday (primary), a small specialty-use sander and a planner are only used once or twice a week (secondary) and never at the same time as each other. In this example, you would size your system to handle the two primary sources (saw and lathe) and only one of the two secondary sources (sander and planer) as they will never run at the same time. Plan with the objective of defining the heaviest use scenario so you can size your system to meet it. Incorporating pickup points that see limited or infrequent use may result in an oversized the system, which increases its total cost to purchase, operate and maintain. Plan wisely, as increasing capacity post installation is nearly impossible. A good rule of thumb is to oversize the system by roughly 10% to ensure proper operation and accommodate any future expansions.

Primary or Secondary Source?

  • Take care to correctly classify each piece of equipment
  • Classifying all sources as primary sources will result in an unnecessarily large system, increasing initial installation costs and making it more costly to operate in the long run.
  • Classifying too many sources as secondary sources will result in an undersized system, resulting in insufficient capacity for normal operations. This will produce production bottlenecks or inadequate venting leading to health/safety hazards.[/box]

Step 3 – Calculate Total CFM Required for Each Branch

In the next step, determine how much CFM you need at each branch of your system. If your source equipment has a built in collar or port identify the diameter (if rectangular calculate the total cross sectional of the duct and convert to round equivalent). On larger sources such as kilns, furnaces or process equipment or for sources with custom-designed venting determine CFM required by consulting with the equipment OEM or by using industry-best practice methods. (Consult a dust collection expert experienced in the specific application for advice.) Finally, using the chart in this section find your duct size and match to column with the required conveying velocity to find the needed CFM for each branch.

Determining CFM for Each Branch in Our Example System – To illustrate we have prepared a sample system layout for consideration of this design step (See illustration below. We will continue to use this same example throughout the following 3 sections.)

Here we have a woodworking shop with a total of (5) pickup points. We have a sander, backdraft table, planer and two floor pickups. Next we determine the CFM required for each branch by duct diameter and then matching it to the appropriate conveying velocity required for wood (see chart in previous section)

  • (1) Sander = 4” OD @ 4,000 ft/m = 350 CFM (rounded)
  • (1)Planer = 5” OD @ 4,000 ft/m = 550 CFM (rounded)
  • (1)Backdraft table = 6” OD @ 4,000 ft/m = 780 CFM (rounded)
  • (2) Floor pickups = 4” OD @ 4,500 ft/m = 400 CFM (For reference only, secondary sources are not counted towards final total.)

Baghouse.com Expert Tips Many types of equipment come with built-in connections for dust collection. These ports are sized by the manufacturer to provide sufficient ventilation while operating the equipment. Simply confirm the diameter of the port to calculate the required CFM (using chart in this section) for the unit.

Step 4 – Create a System Layout and Size Your Main Trunk

Now we need to create a layout of the ductwork system, deciding where it will connect to each machine and where we will place the dust collector. This will determine what size ducts we need including our main trunk line. To help illustrate these concepts we will continue to refer to our sample system first described in the previous section.

Steps to Layout Your System and Size Your Main Trunk

  1. Make rough floor plan showing the location of each piece of equipment
  2. Sketch layout of ductwork connecting each piece of equipment together and running all the way back to the dust collector
  3. Where two primary branches meet combine the CFM require by each branch (using figures from previous step) and calculate the duct size needed to provide sufficient CFM for both branches at the required air velocity (where needed round up to next largest duct size)

Example of a dust collection system layout for a woodworking shop.

Make Floor Plan of Equipment – Take your primary and secondary sources and make a rough floor plan of every piece of equipment. Once you have every source in its approximate location map out the ductwork connection each piece back to the collector. Try to locate your dust collector in a central, convenient location. Safety regulations covering applications involving combustible dusts (e.g. wood, metals, grains, etc.) may mandate placing the baghouse outside or on an exterior wall (along with explosion venting to the outside).

Create Rough Layout of Ductwork System – Now each piece of equipment needs to be connected together and run back to the baghouse. Start at the source farthest away from your collector. Using the CFM requirements you calculated for each branch in the previous step, note the diameter of the duct required and map it out running towards the collector to the point where the next branch connects. Additionally, note the length of each run of duct (important for next step).

Where the next branch connects add the CFM of both lines together and determine what size duct you need for that amount of CFM at the required velocity in ft/m. Increase the size of the duct accordingly and continue mapping the trunk forward. Repeat the process and increase the duct size only at each spot where a primary source connects to the main trunk. Continuing mapping your main trunk (making sure to connect to all primary and secondary sources) until you reach the collector.

Example of a dust collection system layout for a woodworking shop.

Sample shop layout – Notice our calculations for the required CFM, air velocity and the total static resistance generated by the system. Now you can determine the required filter area (i.e. number of filters in the collector) and the fan power. 

Determining Duct Size for Each Branch and Main Trunk in Our Example System – First, we begin with the farthest source the sander. Its built in connection port is 4”, so we begin with a 4” duct leading out of it. Then we continue running it where it connects with the 5” duct coming from the planer. (NOTE We do not increase the size where it meets the Floor Pickup, as this is a secondary source.) By combining 4” duct requiring 350 CFM and the 5” duct requiring 550 CFM, we get 900 CFM +/- at 4,000 ft/m (see previous section for more details). Where these two combine we need a duct to handle at least 900 CFM@ 4,000 ft/m. According to our chart, this falls between a 6” and 7” duct. Per best practice, we will move up and oversize the duct slightly to ensure sufficient airflow and allow for possible expansion later.

Continuing on the 7” duct next combines with the 6” duct running from the backdraft table. The 6” duct requires 780 CFM +/- and the 7” duct requires 1068 CFM. Again, the total combined CFM falls in between the 9” and 10” OD duct, so we size up to 10”. Finally, with all the primary sources connected, the system requires at least 1,680 CFM @ 4,000 ft/m.

Now we have sufficient CFM for all of our primary branches. We also have a safe amount of oversizing to ensure adequate operation and provide a cushion for any possible future expansion. To accommodate the other secondary branches we can install blast gates on all the branches and close off other lines.

Baghouse.com Expert Tips:

  1.  Try to keep the largest equipment closest to where you will place your dust collector.
  2. Try to run your ductwork in the shortest possible route.
  3. Always size up if the required CFM falls between two duct sizes. This allows for future expansion.
  4. Only increase the duct size when a primary source branch connects, but do not forget to run trunk so that all the secondary sources can connect as well.
  5. Consult fire/safety regulations may require the dust collector be located on an external wall or outside.

 

Step 5 – Calculate The Static Pressure (i.e. Static Resistance) of Your System

Static pressure or static resistance (measured in inches of water w.g.) refers to the amount of resistance to airflow created friction and channeling of air through the ductwork. For the system to work the system fan must overcome the resistance created by the ductwork and the baghouse. Accurately calculating the static pressure or SP of the system is crucial for the system to function correctly. To determine the total SP of your system you must add the SP generated by following three elements together:

  • The branch with the great SP (also known as the Worst Branch)
  • The SP of the main trunk line, including any fire protection/prevention devices
  • The resistance created by the dust collector(s). This would include any precleaners (cyclones, knockout chambers, etc.) as well as the filters within the baghouse.

Calculate the SP of all your branches and identify the one with the greatest amount of resistance in w.g. (Likely the branch farthest from the unit with have the highest SP, but not always.) Only figure the SP of the worse branch into your calculations for the entire system’s SP. Next, move on to the main trunk line. Calculate the resistance created by the duct diameter and the length of each section, along with any elbows, splits, or other connections. Finally, identify the SP generated by the dust collector(s), which in most cases will be only a baghouse. For most baghouses plan on a maximum of 5”-7” of resistance (most baghouses should run between 3”-5” differential pressure, but sizing slightly above this figure is conservative and allows for some flexibility).

Steps to Calculate System Static Pressure (i.e. Static Resistance)

  1. Identify the branch with the highest static pressure (Worst Branch)
  2. Calculate the SP of the main trunk line
  3. Determine SP of dust collector

Determining Static Pressure for Each Branch, Main Trunk and The Baghouse in Our Example System

Step 1 – Find the Branch with the Highest SP – Starting at each piece of equipment work back through to the main trunk and determine the total SP of each branch. In our example, the sander branch has the great resistance.

  • Entry loss at equipment adaptor of 1.5” (constant)
  • 10’ of 4”OD duct
    • Reference Table 2-3 shows 100’ of 4” OD duct @ 4,000 ft/m = 7.03”
    • 10’ = 7.03 x .1 (for 10’ feet out of 100’) = 0.70” SP
  • (1) 90° elbow
    • Reference Table 2-4 shows (1) 90° elbow of 4” OD is equivalent of 6’ of straight pipe
    • 6’ of 4 OD = 0.28” SP
  • 25’ of 4” OD duct
    • Reference Table 2-3 shows 100’ of 4” OD duct @ 4,000 ft/m = 7.03”
    • 25’ = 7.03 x .25 (for 25’ feet out of 100’) = 1.76” SP
    • 1.5” + 0.70” + 0.28” + 1.76” = 4.24” Total SP for sander branch

Step 2 – Calculate SP of Main Trunk Line – In our example our ductwork has 50’ of 7” OD duct, followed by 30’ of 10” OD duct at 4,000 ft/m.

  • 50’ of 7” OD duct
    • Reference Table 2-3 shows 100’ of 7” OD duct @ 4,000 ft/m = 3.55”
    • 50’ = 3.55 x .5 (for 50’ feet out of 100’) = 1.78” SP
  • 30’ of 10” OD duct
    • Reference Table 2-3 shows 100’ of 10” OD duct @ 4,000 ft/m = 2.30”
    • 30’ = 2.30 x .3 (for 30’ feet out of 100’) = 0.69” SP
  • 1.78” + 0.69” = 2.47” SP Total SP for main trunk line

Step 3 – Calculate SP for Dust Collector – Each type of dust collectors generates different SP. For this figure, it is best to consult with an experienced baghouse OEM such as Baghouse.com. For our example we will assume a SP of 6” for a baghouse dust collector. Nota: Baghouses are normally designed to operate between 3” – 5” of differential pressure. Baghouse.com recommends being conservative with this estimate and designing in extra capacity to provide a cushion for normal operational ups and downs.

  • 6” Total SP for baghouse

Total SP for our example system:

  • 4.24” for worst branch
  • 2.47” for main trunk line
  • 6” for baghouse
  • = 12.71” total system SP

Now we have all the data needed for completing our system. The dust collection system must provide a minimum airflow of 1,680 CFM through a 10” trunk duct at air velocity 4,000 ft/m with a static pressure of at least 12.71” w.g.

 

Próxima sección – Parte 4 – Consejos adicionales

 Guía de diseño de sistemas de baghouse

/by

The Four Key Baghouse System Design Variables (Part 2 of Design Guide)

For a dust collection system to function adequately engineers must design and operate the system to maintain the (4) key design parameters of airflow (measured in CFM), airflow velocity (measured in FPM), Static Pressure/Static Resistance and Air to Cloth Ratio (or A/C). Changes to any of these key system parameters will result in systemwide performance issues. All four of these parameters are fluid and directly affect the others. Maintaining all at proper levels requires careful engineering, operation and maintenance. Lets review these four parameters one by one.

Airflow in CFM (Cubic Feet per Minute)

CFM – What Is it? – How much air the system moves is measured in Cubic Feet per Minute or CFM. (Related terms include ACFM for Actual Cubic Feet per Minute and SCFM for Standard Cubic Feet per Minute). Most often baghouses are sized and categorized according to CFM. In general, the larger the space being vented or the greater the number of pickup points in the system the more CFM required. The CFM generated by the system fan can be fixed or adjusted (Variable Frequency Drive or VFD Fans). However, total CFM generated by a fan can be affected changes in altitude, ductwork restrictions and sizing as well as resistance to flow created by the system (ductwork + filters).

Why Important? – Without sufficient CFM the sources will not be vented adequately. Poor venting directly causes damage to equipment, high emissions, loss of reclaimed product and hazardous environment (especially of concern in facilities handling combustible dusts or hazardous materials). Low CFM can also negatively affect air velocity, air to cloth ratio, and vacuum pressure, other key design parameters.

Vacuum Pressure (Suction) & Static Pressure (Static Resistance)

What Are Static Pressure and Static Resistance? – Vacuum pressure or suction is measured in inches of water gauge, w.g. and is the basis of a properly functioning dust collection system. The system fan must supply enough suction to pull the materials from the collection point(s) all the way through the ductwork to the baghouse and then through the filters and out to exhaust. To do that it must overcome the resistance to flow created by the filters and the ductwork. Conversely, static pressure or static resistance is a measurement of resistance generated by the ductwork and the filters in baghouse. This also is measured in inches of water gauge.

Why Important? – Without sufficient CFM the sources will not be vented adequately. Poor venting directly causes damage to equipment, high emissions, loss of reclaimed product and hazardous environment (especially of concern in facilities handling combustible dusts or hazardous materials). Low CFM can also negatively affect air velocity, air to cloth ratio, and vacuum pressure, other key design parameters.

Air Velocity and Minimum Conveying Velocity

What are Air Velocity and Minimum Conveying Velocity? – Air velocity within the system is measured in feet per minute, or ft/m. The system must be carefully engineered to keep the air speed within an acceptable range to prevent two major issues. Air speed is related to CFM as follows: ft/m = CFM ÷ cross sectional of duct (i.e. size of duct).

Dust builds up within the ductwork when the air velocity is too low causing blockages and affecting airflow and performance.

Dust builds up within the ductwork when the air velocity is too low causing blockages and affecting airflow and performance.

Why Important? – High air velocity can quickly wear holes the ductwork by means of abrasion (especially abrasive dusts like metals, ceramics, etc.) or can break up delicate conveyed products such as processed foods (cereals), pharmaceuticals, and others. Of greater concern is low air velocity, which can cause dust buildup within the ductwork and lead to poor dust capture at inlets. For a dust to travel suspended in air it must most at or above the minimum conveying velocity for that product. If it drops below that minimum speed at any point in the ductwork the dust will begin to settle or dropout of the airstream, which then accumulate into large piles that eventually choke off the duct. These accumulations of dust within the ductwork create major safety hazards. When combined with an ignition source (such as a spark or ember) they provide ample fuel for a combustible dust fire or explosion, which then can propagate throughout the entire system, being continually fed by dust accumulations further downstream until it reaches the dust collector. Additionally, these accumulations can eventually become so large that the duct collapses under the added weight.

 

Air to Cloth Ratio

What is Dust Collector Air to Cloth Ratio? – The ratio of gas volume (ACFM) to total cloth area (sq. ft.) of the baghouse. First calculate the total cloth area of your collector by calculating the total filter area of each filter (bag diameter x 3.14 x length ÷ 144 [for number of inches in a square foot] = filter cloth area) and then multiply that figure by the total number of bags in the collector. Take the CFM of the system and divide it by the total filter cloth area to get your air to cloth ratio.

Why Important? – For the baghouse to capture the dust from the airstream the unit must have a sufficient number of filters. As you push more air through the same amount of filter material the collection efficiency goes down. Maintaining an adequate air to cloth ratio enables the baghouse to operate at peak efficiencies, collecting more than 99.9% all dust particles that pass through it. For most applications, anything less than near peak efficiency will result in excessive emissions, violating pollution regulations and creating hazardous environment for workers and neighbors.

Putting All 4 Variables Together and Designing Your System

Now that we have discussed the 4 key design considerations, we will now see how to design a baghouse dust collection system so as to maintain all 4 of these parameters within acceptable ranges to ensure proper operation. Our next section is titled: Design Process for Your Baghouse Dust Collection System

Próxima sección – Parte 3 – Calculando el tamaño de tu colector (proceso de diseño)

 Guía de diseño de sistemas de baghouse

/by

Why You Need to Properly Size Your Baghouse System (Part 1 of Design Guide)

Dust collection systems play a vital role in many commercial and industrial facilities. Whether part of a system process, used to capture harmful pollutants from furnaces/boilers, to convey dry bulk product or to maintain a clean and safe work environment, dust collection systems need to function at near constant peak efficiency for facilities to operate safely and productively. While maintenance and proper operation play a large role in keeping these systems running properly, many facilities face challenges due to improper system design and engineering.

Many users rely on outside vendors or so-called “experts” with little to no actual dust collection experience to design and engineer a system for them. Other times vendors may purposefully undersize a system in order to undercut other potential suppliers regardless of how it actually performs in the end for their customer. Still others design their own system in-house thinking it an easy process that just any engineer can accomplish with little to no outside guidance. These cases frequently end with an inadequate dust collection system that cannot meet the needs of the process, resulting in high emissions, lowered productivity, hazardous work environments or all three! So what can facilities do to ensure they do not encounter these same issues?

 

In our experience, an educated user benefits the most and becomes best customer. With that in mind, we have prepared this guide (broken into 4 major sections) to assist users in designing and properly sizing a dust collection system. By following the direction in this guide closely, you can effectively estimate what kind of system you require and then use this information as a basis for gathering quotes and additional assistance.

This guide is NOT an exhaustive course on dust collector design. Each system presents unique circumstances that affect the general operation of a baghouse system. As such, the guidelines present in this guide should be used only to estimate the sizing of your system. A qualified, and experienced dust collection system OEM should be consulted before purchasing any equipment or making design changes.

Now let’s get right into it! First we start with the four key dust collector design variables.

Próxima sección – Parte 2 – Las cuatro variables de diseño de un colector

 Guía de diseño de sistemas de baghouse

Key Points to This Guide

  • Many So-called “Baghouse Experts” know little about proper dust collection design and operation OEMs and sales reps frequently undersize systems to win contracts leaving customers with a system that does not work
  • Educated clients can determine the general size they need and use it as a basis to compare quotes from multiple sources
  • Understanding principles of dust collection system design enables facilities to make better decisions regarding baghouse maintenance, operation y safety

/by

Cómo calcular el tamaño correcto de tu colector de polvo (Serie de artículos)

¿Qué tamaño de colector de polvo necesitas? ¿Cómo determinar cuántos filtros necesitas? ¿Qué relación aire-tela satisface las necesidades de tus operaciones? ¿Cuánta presión de vacío (presión estática) necesitas en el ventilador del sistema? ¿Cuántos CFM necesitas?

 

Calculating the size of a dust collection system

Calculating the size of a dust collection system

Estas son solo algunas de las preguntas que pueden surgir al trabajar con sistemas de recolección de polvo. Al diseñar un sistema nuevo, los ingenieros deben decidir qué tamaño de sistema necesitan antes de comenzar a solicitar cotizaciones a los proveedores.

Existe un peligro cuando las compañías piden a proveedores que diseñen un sistema para ellos. Muchos de los supuestos "expertos en recolección de polvo" son en realidad representantes de ventas que tienen poca formación técnica o experiencia en ingeniería con estos sistemas. Por lo tanto, a menudo venden las líneas de productos que tienen desde un catálogo, sin considerar si el producto es la mejor opción para tu aplicación específica. Otros proveedores recomiendan deliberadamente sistemas subdimensionados para ofrecer precios más bajos que otros competidores, sin importar cómo funcione el sistema para el cliente en el futuro.

Si tienes a cargo el proyecto de seleccionar un colector de polvo, puedes evitar fácilmente que te vendan un sistema subdimensionado al investigar de antemano para obtener una idea general del tamaño del sistema que necesitan. Luego, pueden usar esta información estimativa como base para solicitar cotizaciones de varios proveedores.
Por esta razón, Baghouse.com ha preparado una serie detallada de artículos para ayudar a educar a los usuarios sobre cómo dimensionar correctamente su sistema de recolección de polvo. Cada artículo de esta serie cubrirá un paso diferente en el proceso de determinar tus necesidades de recolección de polvo para tu sistema. Esta serie de artículos será principalmente útil para el personal de planta que busca instalar nuevos colectores de polvo y sistemas de conductos. Sin embargo, la información también puede ser utilizada para solucionar problemas en sistemas existentes (donde la capacidad puede no ser suficiente) o cuando se busca expandir la capacidad de sistemas existentes.

Complete guide to sizing your baghouse

Hacé click aquí para descargar gratis el eBook: GUÍA PARA CALCULAR EL TAMAÑO CORRECTO DE UN COLECTOR DE POLVO

Próxima sección – Parte 1 – Por qué necesitas calcular correctamente tu sistema de recolección de polvo

 Guía de diseño de sistemas de baghouse



Download our FREE Filter & Cage Baghouse Step-by-Step Measurement Guide

/by