How do you know when it's time to change out the filters in your dust collector?
There are typically two reasons people change out their filters:
- The build up of filter cake is so excessive that it is blinding your filters.
- You have a hole/leak in your filter(s).
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 change out, check out our brief video here:
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.
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.
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.
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.
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 your to change out your filters, give us a call.
FACTORS THAT INFLUENCE FILTER LIFE
- Air to cloth ratio
- Volume of dust loading
- Size of dust
- Presence of membranes or coatings
- Dust characteristics (powdery, sticky, shape)
- Air velocity through the filters
- Moisture in the dust
- Ambient air moisture
- Cleanliness of compressed air
- Presence of chemicals – oils, acids, etc.
- Operating temperature
- Frequency of cleaning cycle
- Average differential pressure
- Proper cage fit
- Proper installation