Every filter has some kind of cotton, foams, cahrcoal or a desiccant and these tubes supposed to filter water and oil.. when a compressor pushes air of 250 bar pressure through this tube, how a desiccant decides to hold the water under that pressure but let the air through?
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Compressor filters, do they really work?
- Thread starter Ghulam
- Start date
My guess is the air being pump isn't passing through the filter that fast. If you noticed, once you get up to 200 bar and you have open your vessel valve , it does take a bit of time to get up to 250 bar allowing the air moisture to controlled by the desiccant.
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I am/was going to put 2 filters on my whip from the compressor to the gun. But have some concerns about how much of an increased load that will be on the compressor. I understand you keep track of the dampness of the cotton "plugs" and dry them with a hair dryer. I understand the theory but just wonder how much of an extra load that puts on the compressor.
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Try blowning through one and see how easy it goes through. Our lungs are no way 4500psi.
Let's us know what you found out after the experiment.
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As someone who works in the industry, I can tell if they don't use one on a shoebox compressor just by the smell of the parts during disassembly. I can't explain how they work, but they do.
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The white absorbent filters like the one that came with my YH work in the sense they trap moisture and oil in the air coming out of the YH. The better question is whether they work well enough you can safely depend on them and not add an additional filter. I do not trust the one on the YH works that well so I added another filter with color changing dessicant. I check the dessicant to determine when it needs changed. It takes several runs indicating most of the water is either being vented (every 5 minutes) or trapped in the little white one. But I still feel the extra filter is worthwhile/necessary.
I can't explain how dessicant works but it is a chemical reaction that can be reversed in some media by heat. I tried that once, however, and wasn't happy with the result. So I just throw it away when it changes color.
The only effect of the filters is they are additional chambers that have to be pressurized for your gun or tank to get pressurized. That takes a few seconds. It's like the gun's "tank" is a little larger. The air flows through the dessicant fine, it doesn't impede flow. The air is not flowing real fast through the filters, it is at high pressure but not high volume. That's why it takes awhile for the gun or tank to fill.
I can't explain how dessicant works but it is a chemical reaction that can be reversed in some media by heat. I tried that once, however, and wasn't happy with the result. So I just throw it away when it changes color.
The only effect of the filters is they are additional chambers that have to be pressurized for your gun or tank to get pressurized. That takes a few seconds. It's like the gun's "tank" is a little larger. The air flows through the dessicant fine, it doesn't impede flow. The air is not flowing real fast through the filters, it is at high pressure but not high volume. That's why it takes awhile for the gun or tank to fill.
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Bill rule (SP)? From target forge has done a video or 2 on YouTube using actual test equipment to detect moisture in the air from compressors. The real answer to your question is unless you obtain such equipment and do sound testing you will never really know if your filter works. 100 people can say this one does and this one doesn’t but without actual testing who really knows.
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If one finds moisture in their filters doesn't that PROVE they're working to some degree? Of course it does!
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i hope u r ryt. Whether it flows to vessel the moment compressor starts or build the pressure first. It seems impossible to me, that a filter material can hold water under that much pressure.
An airgun usually have 100 bar, so the compressor would start pushing to vessel @100 bar. Even at that point filter can't be able to hold water molecules
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From my understanding of physics air can be compressed, water cannot. Water molecules, being larger than compressed air molecules, ARE left behind in the filtering media. Whatever the case, anyone who runs a compressor to a tank or gun reservoir WITHOUT filtering for moisture will most certainly have problems down the road!
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At first, set up my post-compressor filter system with cotton filled black YH filter, M80 long gold (charcoal/desiccant) followed by another cotton filled small metal filter. Noticed YH filter cotton insert soaked after filling several guns. Added $125 (eBay) copper-colored water coalescing filter between compressor and black YH filter, clean and dry ever since. Had occasion to remove hoses to two-year old coalescing filter recently, entrance fitting corroded/rusty, exit like brand new, seems good evidence of effectiveness. WM
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If you notice, there are duel filter systems that have a drain on the condensation trap.
I have a single gold tube filter down air from the one that comes with the YH. When I complete my vessel fill, I bleed the air out the vessel to help blow out any trapped moisture. I'm not sure it works that way but I guess it's better than nothing.
I have a single gold tube filter down air from the one that comes with the YH. When I complete my vessel fill, I bleed the air out the vessel to help blow out any trapped moisture. I'm not sure it works that way but I guess it's better than nothing.
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Well of course but isn’t what is most important what is going through into the gun? I mean the systems that make our water drinkable I hope are more than somewhat working.
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I'm not familiar with the gold filters & their workings but every time I'm done running my YH I open the end caps of my filters to let things air dry til my next compressor run.
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It might help to understand that filters are not taking moisture that is in the high pressure air out, the water is not still in the air. Air looses it's ability to contain water when it is compressed. Heating the air raises it's ability to retain air, however. But as the high pressure air flows away from the compressor the air cools and water separates from the air. That is what the filter gets. Just as a paper towel or sponge absorbs water the filter absorbs it. Dessicant is different, it can absorb moisture from air. I use the YH white filter first to filter any oil in the air and to get liquid water. The dessicant is next to get remaining moisture in the air. I arrange the lines to the filters to flow back to the compressor so I can vent moisture that gets back to the compressor. Noticable moisture is removed when I vent. I also often squeeze a little moisture out of the YH sponge filter. I change it after each run. I bought a pack of 100 from AliExpress for a few dollars.
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In order to understand water in air, you have to first understand that water, which we all know is H2O, can exist in three phases: solid, liquid, and gas. We can pretty much ignore solid in our use, although for filtration purposes it is simply the frozen form of liquid. Gaseous water is individual H2O molecules, and liquid water is multiple molecules bound together via hydrogen bonds. This happens when the ability of air to “hold” any more individual water molecules is exceeded, and this limit is a function of temperature and pressure – it is really a limit on energy states of the water molecules. When this limit is exceeded, the water will begin to condense out into a liquid state.
When this condensation happens, it starts as tiny droplets of liquid water suspended in the air charge, much like a fog – it is liquid water at this point, but the droplets have not encountered enough other tiny droplets to become large enough to fall out of the air via gravity. That is why foggy conditions require relatively still air – as the air begins to move more, the droplets connect and fall out faster (or they contact something and stick to it). So if we basically have three different things to “trap via filtration – liquid water that has fallen out of the air stream, small water droplets in the air stream, and the remaining gaseous water vapor that has not condensed out, but could condense out later if the temperature drops or if the pressure rises.
As for tools for active filtration, we have three types:
- Coalescing (remove contaminants by getting them to stick together (coalesce) and drop of out of the airflow - works great for removing water/oil mist in air flow, especially when combined with coolers to reduce the air charge temp and drive more condensation),
- Absorptive (uses physical media to directly capture contaminants, like the tampon type - requires the contaminants to be "big enough" to be captured, thus does not work for vaporized contaminants as it will not trap individual molecules of gaseous water, which are too small),
- Adsorptive (uses a media to adsorb contaminants directly, such as desiccant or charcoal, that capture gaseous contaminants directly via adsorption).
Do note that we can use chillers to further improve the process of coalescing and absorbing – reducing that air charge to at or below the temperature at which it will be used allows us do less drying with adsorptive (or desiccant based) filters, which is a good thing as it reduces either the load on the media or the amount of media we need to use to get the job done. This is why I like the idea of putting a coalescing filter in a bucket of ice water for our use – chill the air further before it gets to a desiccant filter, which should be in the path.
Absorptive filters, like the like cotton pads, simply do not pull vapor out of the air stream (notice that paper towels and napkins don’t get “wet” on humid days), but they will pull the drops suspended in air out of the air stream. This is a viable option as a step in the filtration process, and can even be used without a coalescing filter if the media is large enough, but it is not sufficient by itself if the air charge temperature is still above the final usage temperature, or if the pressure will continue to rise because these changes will lead to further condensation later.
Desiccants work by adsorbing individual water molecules into their structure. The media is typically beads, and at the molecular level these beads are quite porous. As air flows around them, the water vapor is drawn into the bead and bonds to the chemical structure of the material. Such media will even pull water vapor out of ambient air, like silica beads in a safe – so it is important to make sure that the airflow path to the media be closed off when not in use, or the media will loose its ability to work faster than planned. Most desiccant materials get “overwhelmed” by liquid water as it is too much to handle at once. Such media can become overheated and even burst when it encounters liquid water (meaning the beads burst, not that the filter housing). This can result in throwing of fine fragments of abrasive dust into the air stream, which is not good for tank or Airgun valves.
Both absorptive and adsorptive filters are going to use media, and thus must be sized properly. Both will benefit from the use of a coalescing filter before them, as it will reduce the load on these filters – and having either a coalescing or absorptive filter in front of an adsorptive (desiccant) filter is important as they “do not play well” with liquid water at all.
A well-designed system for air guns will always use an adsorptive filter and should use at least one of the other two before the air charge passes through the desiccant to reduce the chance of liquid water hitting the beads.
When this condensation happens, it starts as tiny droplets of liquid water suspended in the air charge, much like a fog – it is liquid water at this point, but the droplets have not encountered enough other tiny droplets to become large enough to fall out of the air via gravity. That is why foggy conditions require relatively still air – as the air begins to move more, the droplets connect and fall out faster (or they contact something and stick to it). So if we basically have three different things to “trap via filtration – liquid water that has fallen out of the air stream, small water droplets in the air stream, and the remaining gaseous water vapor that has not condensed out, but could condense out later if the temperature drops or if the pressure rises.
As for tools for active filtration, we have three types:
- Coalescing (remove contaminants by getting them to stick together (coalesce) and drop of out of the airflow - works great for removing water/oil mist in air flow, especially when combined with coolers to reduce the air charge temp and drive more condensation),
- Absorptive (uses physical media to directly capture contaminants, like the tampon type - requires the contaminants to be "big enough" to be captured, thus does not work for vaporized contaminants as it will not trap individual molecules of gaseous water, which are too small),
- Adsorptive (uses a media to adsorb contaminants directly, such as desiccant or charcoal, that capture gaseous contaminants directly via adsorption).
Do note that we can use chillers to further improve the process of coalescing and absorbing – reducing that air charge to at or below the temperature at which it will be used allows us do less drying with adsorptive (or desiccant based) filters, which is a good thing as it reduces either the load on the media or the amount of media we need to use to get the job done. This is why I like the idea of putting a coalescing filter in a bucket of ice water for our use – chill the air further before it gets to a desiccant filter, which should be in the path.
Absorptive filters, like the like cotton pads, simply do not pull vapor out of the air stream (notice that paper towels and napkins don’t get “wet” on humid days), but they will pull the drops suspended in air out of the air stream. This is a viable option as a step in the filtration process, and can even be used without a coalescing filter if the media is large enough, but it is not sufficient by itself if the air charge temperature is still above the final usage temperature, or if the pressure will continue to rise because these changes will lead to further condensation later.
Desiccants work by adsorbing individual water molecules into their structure. The media is typically beads, and at the molecular level these beads are quite porous. As air flows around them, the water vapor is drawn into the bead and bonds to the chemical structure of the material. Such media will even pull water vapor out of ambient air, like silica beads in a safe – so it is important to make sure that the airflow path to the media be closed off when not in use, or the media will loose its ability to work faster than planned. Most desiccant materials get “overwhelmed” by liquid water as it is too much to handle at once. Such media can become overheated and even burst when it encounters liquid water (meaning the beads burst, not that the filter housing). This can result in throwing of fine fragments of abrasive dust into the air stream, which is not good for tank or Airgun valves.
Both absorptive and adsorptive filters are going to use media, and thus must be sized properly. Both will benefit from the use of a coalescing filter before them, as it will reduce the load on these filters – and having either a coalescing or absorptive filter in front of an adsorptive (desiccant) filter is important as they “do not play well” with liquid water at all.
A well-designed system for air guns will always use an adsorptive filter and should use at least one of the other two before the air charge passes through the desiccant to reduce the chance of liquid water hitting the beads.
I have an Altaros booster, I use a coalescing filter and desiccant before the air goes into the unit. The unit itself has another desiccant filter in it. The high pressure air then goes into a molecular sieve filter before it enters my tank. The desiccant in the Altaros never gets saturated. I’ve been using this system for 7 years with no issues whatsoever.
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Alan,
Thank you for the review. Prior to reading this I was not sure if I did this correctly or how much it would help to minimize water/vapor from getting into my rifle's. If I understand you correctly I am doing a reasonable job of protecting my rifle tanks from corosion.
I am using what I believe is a centrifugal coalescing filter (GOLD) as my 1st stage coming off of an Omega Trail Charger Compressor and then continuing the HPA through an Omega Clean Air Molecular Sieve Desiccant Filter (SILVER,a rebadged Coltri) as a 2nd stage prior to filling my airguns. Do you see any real additional benefit to adding a Tampon filter to it and if yes at what point in the pathway?
BP-1
Thank you for the review. Prior to reading this I was not sure if I did this correctly or how much it would help to minimize water/vapor from getting into my rifle's. If I understand you correctly I am doing a reasonable job of protecting my rifle tanks from corosion.
I am using what I believe is a centrifugal coalescing filter (GOLD) as my 1st stage coming off of an Omega Trail Charger Compressor and then continuing the HPA through an Omega Clean Air Molecular Sieve Desiccant Filter (SILVER,a rebadged Coltri) as a 2nd stage prior to filling my airguns. Do you see any real additional benefit to adding a Tampon filter to it and if yes at what point in the pathway?
BP-1
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