ABOUT CARTRIDGE FILTER MEDIAS
The most critical component of a dust collector filter is the media. Filters can be made of “80/20” (eighty twenty), Cellulose, and Polyspun media. Each filter media has specific characteristics and uses.
Cellulose is the least expensive filter media. This element is made of paper.
The filter is designed to be a “throw away”. The media is very weak and likely to tear or allow holes to pierce easily. Cellulose filters are inefficient at the time of installation and use the dust that builds up in the filter pleats to become part of the filtering media. The filter pleats are designed to “fill up” with dust. When the pleats fill up or when the differential pressure become high the filter is replaced.
Recently, some manufactures have begun to add coatings to paper to increase the efficiency of the paper media. One particular coating is called “Nano Fiber” Why would this be done? Simply, because you can make a cheap filter more efficient. Nano Fiber on top of paper will raise the efficiency to a MERV 13.
80/20 (eighty twenty) filter medias are made of 80% paper, and 20% polyester materials.
This is still a paper cartridge, and will act similar to a paper cartridge in its filtration ability. The only advantage of and 80/20 over a cellulose filter is that the media is slightly stronger due to their polyester strands. When coating an 80/20 with a “Nano Fiber” the efficiency of the filter is increased to a MERV 14.
Polyspun media is superior to both 80/20 and cellulose. A polyspun filter can typically last 3-4 times longer in a system. The filter is designed to shed the material built up in the pleats every time the filter cleans (on line).
It is comprised of interwoven fibers, and cannot be torn or punctured under normal usage.
Multiple coatings and finishes can be added to the base material to solve issues such as moisture resistance or static dissipation. Polyspun media will support combustion, but paper media will ignite much easier. Polyspun medias are considered “cleanable”. A professionally cleaned Polyspun filter can be cleaned and re-used multiple times.
CLEANING CARTRIDGE AND CANISTER FILTERS FOR DUST COLLECTORS
Significant savings can be realized by cleaning the dirty plant filters. Cellulose, 80/20, and Polyspun filters can all be cleaned and re-conditioned.
Cleaning and re-using filters will promote and verify your sustainability and “green” efforts.
If you are considering filter cleaning, filters made of Polyspun media are by far the best choice. The media is very durable and will outlast all other options. As the filter reaches the end of its useable life, failures are easy to detect. Unlike paper filters, when a Polyspun filter fails, the hole is easily visible to the naked eye.
CARTRIDGE FILTER MEDIAS – WHY DO THEY FAIL?
Filters made of Polyspun media are very durable.
Failure of a Polyspun filter usually occurs for one of three reasons:
1. The media begins to wear on the pleat edges from product abrasion to the media (past the useable life of the filter).
2. The filter is rejected due to bent metal ends from rough handling by the installer (most common reason).
3. The system’s Mag pressure is high and the filter crushes (the dust collector hopper is not emptied, airlock fails, or filter airflow is restricted).
Paper media will either tear or wear thin in some spots. When the media wears thin, small pin holes may develop. Because a paper filter bypasses some dust, it can be cumbersome to determine the root cause. Failures in paper filters are much harder to locate. One obstacle is that the pleats are very close together – making a tough situation even harder. It is difficult even for a professional with the correct equipment to locate pin holes in paper medias.
In conclusion, a Polyspun filter will not fail as easily, and it is easier to identify the actual cause and location of the failure.
WHEN SHOUD I CHANGE MY FILTER? IS IT DIFFERENT FOR EACH MEDIA?
There are three schools of thought.
1. There is a failure
2. Change at outage (every “X” calendar days)
3. When the magnehelic gauge rises and does not drop.
USING A MAGNEHELIC GAUGE TO MONITOR FILTER LIFE
In general the best method to get the maximum life out of your filter is to watch the Mag gauge. Take a baseline reading at installation and document the readings daily. Different medias will respond differently after initial installation (Paper and 80/20 will behave in the same manner and for the sake of this discussion we will refer to both as a paper filter).
Polyspun media – After installation the mag gage will slowly climb over the next several days and level out. You may still notice some fluctuation in the readings after the cleaning cycle. But, in general it will rise to a point and steady out. When the filter begins to plug the readings will begin to steadily climb and will not drop after the cleaning cycle. When you see this it is time to plan a change out. Ignoring this will cause permanent structural damage to the filters or the dust collector.
Paper media – Paper initially will have very low mag readings. This is because the filter is not very efficient even at the beginning of its life. As the paper catches more dirt, it becomes more efficient and builds up dust the mag gage readings will increase. In general, with a paper filter, the DP will slowly climb until the paper fills with dust. The trick with paper is determining at what point the paper will tear – or at what point you are straining your fan motor.
In general, it is best to change a paper filter around 6 water column inches.
CHANGING THE FILTER BASED ON TIME OR OUTAGE
Paper and Polyspun filters will react basically the same. Typically, it is difficult to know if the filter is “dirty” and you have run its full life-cycle and worth. The opposite problem can also be true; If production levels are high, the filter may be restricted and cause an unexpected outage. If the filter is plugged, other related issues are:
a) Higher motor amperage draw,
b) Hotter running fan bearings, and,
c) Lower transfer rates (if using a pneumatic conveying system).
If you are using this method you are either leaving money on the table, or causing system problems.
CHANGING THE FILTER WHEN IT FAILS
This method is not recommended. If you wait until you are passing dust, production must stop to change the filter. Many times the ductwork will fill, and the stack will layer with dust.
-Paper media – The filter is simply thrown away anyway.
-Polyspun media- You are discarding an expensive filter.
REASONS TO HAVE A CHANGE-OUT PLAN OR CYCLE
– Less motor and bearing failures due to heat
– Less electric usage (amperage load)
– Better flow rates of material on pneumatic convey systems
Always compare “apples to apples.” If one supplier is much cheaper than another, investigate the reason. Most quality manufacturers get the majority of their components from the same manufacturer. Reputable manufacturers and suppliers will have nearly the same material costs.
USE WITH FOOD AND PHARMACEUTICALS
Polyspun media is not organic in nature and will not become a “host” for mold or mildew spores. Because of these properties, food and pharmaceutical manufacturers make Polyspun filters their filter of choice.