Filter Bags & Leak Testing – How Important is it?

,
Filter Bags

Leak testing being performed in a Baghouse

By Dominick DalSanto
Environmental Technologies Expert & Author
Baghouse.com

Why Periodic Leak Testing of Filter Bags is Vital

Operating a dust collection system with leaking filter bags defeats its sole intended purpose. A few leaking filter bags or even one within a collector/system can result in a substantial emissions increase. Leak testing of your Baghouse filter bags needs to be a regular part of any maintenance program to ensure system efficiency, and maintain compliance with emissions/safety regulations and avoid the fines and/or safety hazards that come with it.

All filter bags will eventually wear all out and need to be replaced. Baghouse maintenance programs should include periodic leak testing to ensure a few or even one faulty bag does not reduce the operating efficiency of the entire system. On occasion, a defective filter will fail early and need to be replaced. In other instances there may be a temporary or unanticipated event that can cause of premature failure of Baghouse filter bags. Once identified these should be investigated to ensure the incident does not occur again, and determine the extent of the damage done to the system. Examples may include: abrasion, thermal durability, and chemical attack.

  • Abrasion from several different sources often leads to excessive wear (and therefore premature failure) of the filter bags. The most obvious is caused by excessive particulate loads in the gas stream. This may have been caused by the unexpected failure, or shutdown/maintenance of a pre-filter (such as a cyclone, or air scrubber for NOx and SOx). Poor design may also lead to particulate laden air striking the filters in certain spots more than others such as near the cuff, or dirty-air inlet. Other sources of abrasion damage include: improperly installed filters that rub against each other, and excessive cleaning cycles.
  • Degradation of the filter bags’ Thermal Durability may also be a potential cause of early failure. When operating temperatures that rise above the designed limits of the fabric, whether for short or long term, filters will begin to degrade and eventually fail. Changes in the plant process, fuel source, maintenance shutdowns of other systems, etc…may result in temperature spikes that will irreparably damage Baghouse filters.
  • Chemical attacks can also result in bag failure. These can occur when gas stream characteristics are not taken into consideration when selecting the filter fabric and/or treatments/finishes. Other times unexpected changes occur in the gas stream that cause changes in the composition of the gas. Operating temperatures may also fluctuate,  dropping below the dew point allowing condensation of the chemicals on the fabric.

Filter Bag Leak Testing – How it is Done

To perform a standard leak test several things need to be done before the actual test can take place. First, since testing requires temporary isolation from the facility process, and shutdown, you must determine the best time for each unit and/or compartment to be tested. Second, safety measures for plant personnel must be taken into account when estimating total down time. Units must be given sufficient time for cooling, atmospheric testing to check for harmful gases, and personnel assigned to perform both the test and fulfill any and all safety regulations regarding confined space entry (both OSHA, and In-house). Once the preliminary steps have been taken, the actual testing can begin.

Filter Bags - Leak Testing

A vital part of any Baghouse system maintenance plan is regular leak testing of the filter bags.

First, florescent leak detection powder is added upstream of the unit such as at a maintenance access in the ductwork. Then after sufficient time has past for the powder to work its way through the system, the unit is shutdown. Once it is possible, a technician will enter into the unit with a UV light source i.e. a black light to examine the filter bags for leaks. The powder fluoresces under the UV light, thereby making it easy for the technician to see even the smallest of holes. The technician makes note of any faulty filters, which can then be replaced.

Regular Maintenance is Key to Getting the Highest Efficiency from Your Baghouse

Baghouse systems are the most efficient, and cost effective solution for particulate matter control in industrial settings – but only if they are maintained properly. A vital part of any Baghouse system maintenance program is regular leak testing of the filter bags. By conducting this and other maintenance tasks, your Baghouse system will operate smoothly, and provide the best of results.

Looking for Leak Testing Services?

Baghouse.com has the expertize to locate and remedy leaks in not only your filters, but also duct work, collector housing, and more. To learn more about Baghouse.com leak testing services and leak testing supplies or receive a free quote on Baghouse leak testing please contact us for a free quote.

 

 

8 replies
  1. dominickdalsanto
    dominickdalsanto says:

    I don’t know of any videos out there showing this. However, we are currently planing to produce a series of videos detailing this, and other Baghouse maintenance and operational procedures. When they are ready we will publish them here on Baghouse.com for everyone. Thanks for your comment.

    Reply
  2. Jack Sarcinella
    Jack Sarcinella says:

    Our bag house cfm continues to drop throughout the day, start up in the morning it’s fine 40000, by 10:00 am it is down to 32000 cfm and slowly drops

    Reply
    • dominickdalsanto
      dominickdalsanto says:

      Jack,

      Thanks for your comment. CFM will drop as vacuum pressure goes down. Vacuum or suction goes down when the differential pressure rises. Differential pressure rises when the filters get dirty. So it sounds like your cleaning system can’t keep up with the load you are putting on your bags, so your bags get dirtier throughout the day and then begin to choke off the airflow.

      How long have you been running the current set of bags? What kind of cleaning system do you have (pulse jet, reverse air, shaker)? Many times these kinds of problems arise from using filter bags for too long (i.e. your bags are blinded and need to be replaced but you keep using them) or because the cleaning system is not functioning properly. Since you start out at a higher airflow it seems more likely that your cleaning system is not working at 100%. You might need to change the cleaning cycles, (if pulse jet) the diaphragm valves, pulse pressure, on-time/off-time, etc. Give us a call when you can and we will be happy to discuss a few options for you to look at to fix the problem.

      Reply
  3. Jackson Gebrieal Joseph
    Jackson Gebrieal Joseph says:

    I would like to get some predominant damages in filter sleeves and from their to reach an analysis ,kindly help us with photographs

    Reply
  4. SAJU SIMON
    SAJU SIMON says:

    Hi, I am Saju Simon working in a Filter bag manufacturing company in Quality & Technical service Dept.

    I want to know the RABH bag failure : Damage was like abrasion & torn the fabric. Heavy Dust accumulation found in the clean air plenum. Is there any chance of crack in the partition wall?

    Reply
    • dominickdalsanto
      dominickdalsanto says:

      yes, a leak in the dividing wall is certainly possible. Abrasion is going to come from a few different sources: (1) high velocity inlets, (2) full hoppers disrupting the airflow within the unit, (3) too few bags for the CFM (4) leaks inside the unit. Do a leak test to see if there are any leaks. Next, determine if the filters are all being worn down evenly or in certain spots or only certain sections of the unit.

      Reply

Trackbacks & Pingbacks

  1. […] use baghouse filters made from older materials that are not as efficient as newer materials such at PTFE membrane. Additionally, due to shrinking maintenance budgets many dust collection systems are in a state of […]

  2. […] for the cement industry, requiring periodic maintenance program improvements, even a single bag leak can take you out of compliance.   

Industrial-commercial-institutional boiler considerations: […]

Leave a Reply

Want to join the discussion?
Feel free to contribute!

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.