Do you have a woodshop and you are having dust collection problems?
■ Not enough suction at the pickup points?
■ Contaminated recycled air into the facility?
■ Danger of combustible dust in ducts/baghouse?
You will find this article super interesting!
Background
Poor suction, inefficient dust collection, and loads of resources spent on maintenance were some of the problems this plant was experiencing
The US Army’s Aberdeen Proving Ground woodshop was working with an aging dust collection system that could no longer meet their needs. Their existing cyclone and baghouse setup suffered from poor suction, inefficient dust collection, and loads of resources spent on maintenance.
To make matters worse, the return air system consisted of a makeshift, home-built plenum that was not functioning effectively. These issues created a challenging work environment and prompted the woodshop to seek a reliable, long-term solution.
Scope Of Work
The goal was to replace the outdated system with a modern, efficient solution while addressing the following challenges:
● Poor suction and collection performance.
● Difficulty with the maintenance of the equipment
● Inefficient and noisy return air management.
Baghouse.com was tasked with designing and installing a new dust collection system that integrated seamlessly with the existing ductwork.
Solution
Baghouse.com dispatched a technician to assess the woodshop’s existing setup and understand its operational needs. A thorough inspection was conducted on-site, and standard sizing factors were used to engineer a tailored solution.
Baghouse.com installed a new cyclone and a cartridge collector
● High-performance rotary airlocks to eliminate dust discharge issues.
● An engineered return air plenum to replace the makeshift one, reducing noise and improving airflow efficiency.
The new system was carefully integrated into the existing ductwork while addressing spatial constraints during installation. The project was completed within three months of the proposal’s approval.
Conclusion
Some of the immediate improvements the new dust collection system delivered were better suction and airflow performance
The new dust collection system delivered immediate improvements. The woodshop experienced significantly better suction and airflow performance. The engineered return air plenum also reduced noise levels.
From initial evaluation to final installation, Baghouse.com provided high quality customer service, proving they are a trusted partner for even the most demanding projects.
Dust Collection Expert, Technical Writer & Editor at Baghouse.com
Andy Biancotti believes that knowledge is one of the best investments any company can make. As Editor and Marketing Manager at Baghouse.com, he enjoys interviewing engineers, technicians, and customers to capture the real-world lessons behind successful dust collection projects and turn them into practical resources that others can learn from. With more than two decades of experience in industrial maintenance, operations, and technical communication, his goal is simple: help people better understand their systems so they can work safer, smarter, and more efficiently.
https://baghouse.com/wp-content/uploads/2024/12/Case-Study-Aberdeen-Proving-Ground.png10801920Andy Biancottihttps://www.baghouse.com/wp-content/uploads/2018/03/BH-Logo-Alt-01.pngAndy Biancotti2024-12-30 15:33:232026-05-23 19:24:20Case Study — Turning Challenges into Solutions at a Woodshop
Dust collector operators typically utilize cleaning systems to help them ensure effective dust control for their process areas while saving compressed air (which is very expensive when you look at your electric bill). And, for as much as some consider that the cleaner the filter is, the better it works, that is not always the case. Although some will suggest cleaning the bags on a regular basis using a timer setting… in this article you will learn why setting up your cleaning system based on the differential pressure is better for you.
In order to understand all the reasons, let’s start with the cleaning basics.
What is Pulse Jet Cleaning?
During pulse jet cleaning, a reverse flow of clean compressed air puffs a row of bags outwards, dislodging the dust cake on each bag’s surface. The bags react to the initial shock of compressed air, followed by a bubble-like expansion that moves along the bag length.
During pulse jet cleaning, a reverse flow of clean compressed air puffs a row of bags outwards, dislodging the dust cake on each bag’s surface. During this cleaning cycle, the bags in the row being pulsed do not inflate all at once, but in a wavelike manner, which enhances cleaning. The bags react to the initial shock of compressed air, followed by a bubble-like expansion that moves along the bag length. During the cleaning procedure, the baghouse remains online, and filtration continues, with no downtime required.
What is Differential Pressure?
During pulse jet cleaning, the compressed air accumulated in the air header reaches the blowpipe with a frequency and strength determined by the controller, the gauge and the diaphragm
Differential pressure in a dust collector is the difference in air pressure between the dirty side of the collector and the clean side (these two sides divided by the tubesheet). When dust particles are collected by the filter, they build up on the filter surface, making it harder for air to pass through. This creates a pressure difference: the air inside the filter becomes more pressurized compared to the clean air outside the filter.
As the dust builds up, the pressure difference increases, which can affect the efficiency of the dust collector. High differential pressure usually means the filter is getting clogged and needs cleaning. Monitoring differential pressure helps ensure the dust collector is working properly and efficiently.
Why is It Important to Monitor Differential Pressure?
Just as blood pressure indicates the health and efficiency of the circulatory system, differential pressure provides a vital measurement of how well the dust collector is functioning.
Differential pressure can warn us when the baghouse needs help. It can be as simple as indicating when it’s time to pulse clean filters or more extensive service, like it’s time to replace the filters. Continuously monitoring pressure drop can reveal problems early, when they are faster, easier and cheaper to fix, and helps extend bag life.
Why Set Cleaning Based on Differential Pressure Instead of a Timer?
Setting your cleaning based on differential pressure helps stop wasting compressed air. This is because the filters are cleaned only when the pressure reaches a certain level, which prevents overuse. It’s important to maintain the right amount of dust cake (the layer of dust on the filter) because cleaning too often or not enough can cause problems. Under-cleaning creates high differential pressure, while over-cleaning wears the filters out faster.
DID YOU KNOW?
The primary benefit of differential pressure controllers is their ability to program a high set point (when a filter cleaning system turns on) and a low set point (when the cleaning system turns off). Usually the low and high points for the differential pressure are 3” to 5” respectively. By programming the high and low set points effectively, the controller triggers filter cleaning only within the desired range.
During normal use and operation, these controllers monitor the differential pressure across the filters in the collector. The dust collector operator receives a visual indication of the pressure drop across the filters, indicating how clean or dirty the filters may be. Typically, the lower the indicator value for pressure drop, the cleaner the filters, and the higher the value, the dirtier the filters.
Dirty filters tend to provide better filtration efficiency with their cake of accumulated dust, but they require additional energy from the fan in order to maintain airflow volume.
In summary: Your dust collector’s cleaning system does not need to run continuously or clean in fixed periods of time. Using the differential pressure to control the cleaning will save you lots of money and time, since the system will only clean when is necessary, and your filters will last longer.
How Often Should We Monitor the Differential Pressure?
A good preventive maintenance program should include daily (or per shift) checks of the filter differential pressure on each pulse jet unit. This includes visually inspecting and listening to each collector while it’s running to check the pulsing sound and frequency, as well as checking the compressed air pressure in the cleaning manifold before and after pulses. Weekly, monthly, and longer-term checks should also be included. A simple and effective way to do this is to assign one person per shift to monitor the dust collectors and record that information. After a short time, they will become familiar with the normal differential pressure trends and sounds, helping them quickly identify any issues.
What Are The Best Settings For Your Pulse Cleaning System?
Pulse Duration
It’s important to set your pulse time correctly. We recommend a pulse duration between 300 and 500 milliseconds. This is enough time to allow a solid “pop” of air, without an additional “Shhhh” with it. This provides a strong burst of air, without wasting air with additional unnecessary flow. A pulse that lasts too long results in wasted air after the initial “pop,” as the lower pressure doesn’t improve cleaning. If pulses are too short, they might not clean the filters thoroughly, leading to premature wear. You can adjust pulse duration on the timer board or controller.
Pulse Frequency
The key to effective pulsing is giving the manifold enough time to recover the compressed air between pulses. Avoid pulsing too frequently, as this can prevent the manifold from refilling to the correct pressure. If the pressure isn’t high enough, cleaning will be inefficient, leading to wasted compressed air. Always ensure there’s enough delay between pulses to allow the manifold to recover properly. This can also be set on the timer board or controller.
Pulse Sequence
It might seem logical to pulse the filters in row order, but this actually wastes air. When row 1 is cleaned, its lower static pressure allows air to take the path of least resistance, potentially carrying dust back into row 1 during subsequent pulses. This reduces the effectiveness of the cleaning. Instead, we recommend pulsing in a non-sequential order. For example, pulse rows 1, 4, 7, and 10 first, then rows 2, 5, 8, and 3, 6, 9, repeating. This method ensures better cleaning and minimizes air waste. You can change the sequence by adjusting the wiring on the timer board.
President | Dust Collection Engineer | Industrial Air Pollution Control Specialist
Matt Coughlin is an author, engineer, and dust collection expert specializing in industrial filtration systems, air pollution control, and process ventilation. With more than two decades of experience in the dust collection industry, Matt has helped design, troubleshoot, and optimize hundreds of dust collection systems across a wide range of industries, including cement, mining, food processing, woodworking, metals, power generation, chemical manufacturing, and bulk material handling. Born and raised in Southern California, Matt continues to work closely with industrial facilities around the world, helping companies improve their dust collection performance through engineering expertise, practical solutions, and long-term technical support.
https://baghouse.com/wp-content/uploads/2024/12/DP-or-Timer.png10801920Matt Coughlinhttps://www.baghouse.com/wp-content/uploads/2018/03/BH-Logo-Alt-01.pngMatt Coughlin2024-12-23 20:17:142026-06-19 18:04:21Why Set Cleaning Based on Differential Pressure Instead of a Timer Setting?
Purchasing and maintenance people commonly call Baghouse.com requesting assistance to figure out what kind of filter bags they need for their top load baghouse. Often, they do not know which measurements they need to identify the filter size and configuration required to quote replacement filters for their baghouse.
This short article will explain the key features of the most common baghouse filter style: the top load, snap band style baghouse filter.
Top load baghouses are known for their efficiency, reliability and ease of maintenance, making them a popular choice for many industrial applications.
A top load baghouse has a housing with the filter bags arranged so that they hang vertically. The dirty air ductwork usually connects to the baghouse hopper, allowing the dirty air to enter from the bottom of the filters.
The dust particles are captured on the outer surface of the filter bags (falling to the hopper), while the clean air passes through the filters and then travels up through the bag and out the top of the housing.
In top load pulse jet baghouses, the filters are installed into the tubesheet from above. The tubesheet is a metal plate in the baghouse where the filters are installed, separating the clean air from the dirty air. On a pulse jet baghouse, the tubesheet is near the top ¼ of the baghouse and it is a smooth steel sheet with uniform holes into which each filter is installed.
To allow access to the filters, smaller units will generally have removable doors or hatches on the top of the unit surrounded by railings while larger units will have a walk-in clean air plenum which allows entry to the baghouse through a door in the side.
Snap Band Filters for Top Load Baghouses
Cut view of the ring (snap band) and the layer of sown fabric around it that allows for a tight fit against the tube sheet
The snap band is a metal ring sewn into the top of the bag and covered with fabric. The snap band is used to secure and seal the filter bags to the tube sheet.
The pressure from the band pushing against the sides of the hole (when aligned correctly) forms an airtight seal.
To install a snap band bag, the bag is inserted into the round tube sheet hole. The snap band is deformable, allowing the user to manipulate its shape and insert the band into the tubesheet hole. When released, the snap band “snaps” into place, tightly locking the filter into the hole.
Once installed, a metal wire cage is inserted into the cage to hold it open during operation. Then the blowpipes are installed above the filters.
Why Are Snap Band Filters So Popular?
Snap bands ensure a tight fit at the connection points between the filter bag and the tubesheet, preventing air or dust from bypassing the filter bag. Additionally, they are easy to install and more reliable than older methods that require the use of hold down hardware or clamps to secure the bags into the tubesheet.
Snap Band Filter Bag & Cage Terminology
The relationship between snap band size, bag diameter, and cage diameter has to be carefully calculated, since each component plays a crucial role in ensuring the effective installation, sealing, and performance of filter bags.
Here is a brief explanation of each one of these dimensions:
● Tubesheet Hole size/Snap Band Size
An accurate measurement of the tubesheet hole will ensure that the snap band of the filter will have a tight fit
The tube sheet hole size refers to the diameter of the opening in the tubesheet where the filter bag’s snap band is inserted. This size must match the snap band diameter to ensure a tight fit and prevent leakage or bypass of dust-laden air. Snap bands are sized down to 1/32” so this measurement should be taken with calipers if possible. Always measure across the center of the hole in a straight line from one edge to the opposite edge.
● Bag Diameter
The bag diameter refers to the width of the filter bag when laying flat
The bag diameter refers to the width of the filter bag body (NOT the snap band at the top of the bag, which is considered a separate piece). Since we cannot accurately measure the true diameter of the bag outside of a proper jig in the factory, we usually ask customers to measure the flat width instead, which is the width of the bag when laid flat. The bag diameter is almost always slightly smaller than the snap band/tubesheet hole size.
● Cage Diameter
The cage diameter is the outside diameter (OD) of the cage body measured at the center of the cage
The cage diameter is the outside diameter (OD) of the cage body that goes inside the filter bag. The cage diameter will always be slightly smaller than the bag diameter, usually ¼” smaller. If the bags fit too tightly to the cage, the cages will be very difficult to install and remove, and the bags will not flex properly when pulsed and the cleaning power will be reduced, thus contributing to poor operation of the system.
So, when looking to get replacement filters and/or cages for your pulse jet baghouse, you need to gather the following information: (1) tubesheet hole diameter, (2) the bag flat width and length and (3) the cage body outside diameter (OD) and length.
If you are unable to shut the unit down to take the hole measurement, we can still quote you the bags with only the bag flat width and length. Then, once you place an order, we can confirm the exact tube sheet hole size by having you send us a used bag to test fit at our facility. Alternatively, we can send you a pre production sample bag to test fit before we release your order to production.
Instructions to Measure Snap Band Filter Bag & Cage Size Step by Step
With so many different baghouse manufacturers, there is no “standard” size for top load bags. However, there are some common sizes/configurations that are used by multiple OEMs. Common size combinations include:
Small diameter bags: 4” and 5”
● 5” tubesheet hole, 4.5” bag diameter, 4.25” cage diameter
● 5” tubesheet hole, 4.625” bag diameter, 4.5” cage diameter
● 5” tubesheet hole, 4.875” bag diameter, 4.5” cage diameter
Large diameter bags: 6”
● 6” tubesheet hole, 5.875” bag diameter, 5.5” cage diameter
● 6” tubesheet hole, 5.875” bag diameter, 5.625” cage diameter
● 6.2” tubesheet hole, 5.875” bag diameter, 5.5” cage diameter
● 6.25” tubesheet hole, 6” bag diameter, 5.875” cage diameter
Measuring Pleated Filters For Top Load Baghouses
Pleated filters can be used in top load baghouses, often as retrofits for units originally designed to take traditional bags and cages. Some units are designed from the factory to use pleated filters. This is most common with small bin vent style units. Would you like to know if pleated filters would be a good option for your baghouse? Contact us to review your application.
Similar to bags and cages, when looking for replacement pleated filters, we will need to know the tube sheet hole size along with the filter diameter and length.
Size drift in top load baghouses can be quite risky to the efficiency of your dust collector. This happens when measurements are taken inaccurately, and over time, the bags end up being a bit too big or too small for the system.
This can lead to various issues, like:
● Reduced filtration efficiency
● Compromised dust capture
● Increased emissions
● Potential damage to equipment components
To prevent these problems, it’s important to measure accurately and keep an eye on things to catch any drift early.
Additional Tips When Changing the Filters
Any cages that are bent, rusty, or have shape edges should be discarded and replaced. Filters that are installed onto damaged cages will suffer early filter failure.
● Before removing the filters, the blow pipes must be removed to allow access to the tube sheet.
● If reusing cages, these must be carefully removed and set aside so as not to damage them before putting new filters on them and inserting them back into the tube sheet.
● When reusing existing cages it’s usually best to remove only a section of filters at once, since there is only limited space to stack the cages at the top of the baghouse.
● Any cages that are bent, rusty, or have shape edges should be discarded and replaced. Filters that are installed onto damaged cages will suffer early filter failure.
Understanding the dimensions and components of a top load baghouse will help us order the exact replacement pieces, proper installation, sealing, and long filter life.
Do you have any questions or need the advice of an expert in dust collection?
Dust Collection Expert, Technical Writer & Editor at Baghouse.com
Andy Biancotti believes that knowledge is one of the best investments any company can make. As Editor and Marketing Manager at Baghouse.com, he enjoys interviewing engineers, technicians, and customers to capture the real-world lessons behind successful dust collection projects and turn them into practical resources that others can learn from. With more than two decades of experience in industrial maintenance, operations, and technical communication, his goal is simple: help people better understand their systems so they can work safer, smarter, and more efficiently.
