By Dominick DalSanto
Environmental Technologies Expert & Author
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.
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.