Others Pre dryer

[AtlasAirguns]

I've been experimenting with feeding my GX compressors nitrogen at an inlet pressure of 5-10 psi and a flow of something on the order of 20-25 cfm. It does several things,
1) it's dry
2) it lower the compression slightly, making the compressor run better with a slight cooling effect
3) fills faster, with the help of inlet pressure being higher, and no need to fill a large filter, so it runs cooler
4) no need to mess with filters that we have no good way of knowing if they are working except inspecting our rifle cylinders, and then, if they're not working, it's too late.
5) it cheaper than filters, as 2215 psi bottled nitrogen is cheap

I'm by NO MEANS the first person to try this, in fact, I got the idea to try from reading what others have done. I just perfected my setup and am happy it works so well. GX CS2 compressors have a 1/2" NPT thread on the handle/inlet, so fittings are easy to find. I also have a CS3, which uses a small tube to hold the filter cotton, which I'm going to try and adapt to connect some kind of hose to. That's in the works, but for now, the CS2 is the berries. I only fill rifles with cylinders from ~200-500cc, and filling is super fast. I've attached a pic of my setup, the blue filter on the inlet has no media in it. It is simply an air chamber to dampen the flutter of the air gauge needle and keep the supply of air constant.

Interesting may I ask if I'm getting this correct..you are compressing nitrogen from the tank into smaller tanks correct?

 

[elwoodblues]

I have been using Nitrogen to feed my compressors since I got into PCP's a couple years ago, It is the way for bone dry "air". I spent the last 50 or so years in the welding and compressed biz so I have a very good understanding of making this work. Started with a GX CS2 inlet in handle 1/2" npt inlet cap, then I got a Tuxing twin cyl for 6.8lL tank and 580 cc bottle guns it has a 1/4" inlet "muffler" intake, and now I mainly useing a GX CS4 .
I feed the cs2 about 8-10psi the Tuxing gets about 15psi and the CS4 gets 25cfh through a flow gauge all are fed with 1/4 inch hoses. Dive shop air is NOT DRY if you remove all the moisture it dries the user mucus membranes out .
If it would have worked 79% nitrogen and 21% oxgen called reconstituted air then been used everywhere but again way to DRY for people to breath for very long. Nitrogen has a dew point of 0.01ppm at -70F.

 

[elwoodblues]

I have been using Nitrogen to feed my compressors since I got into PCP's a couple years ago, It is the way for bone dry "air". I spent the last 50 or so years in the welding and compressed biz so I have a very good understanding of making this work. Started with a GX CS2 inlet in handle 1/2" npt inlet cap, then I got a Tuxing twin cyl for 6.8lL tank and 580 cc bottle guns it has a 1/4" inlet "muffler" intake, and now I mainly useing a GX CS4 .
I feed the cs2 about 8-10psi the Tuxing gets about 15psi and the CS4 gets 25cfh through a flow gauge all are fed with 1/4 inch hoses. Dive shop air is NOT DRY if you remove all the moisture it dries the user mucus membranes out .
If it would have worked 79% nitrogen and 21% oxgen called reconstituted air then been used everywhere but again way to DRY for people to breath for very long. Nitrogen has a dew point of 0.01ppm at -70F.

 

[Danman]

Man I'm late to the party. OK so in my S510 manual it says the prefered method to fill the gun is with "dry" air from a tank. However dry that is, obviously not completely devoid of moisture as Elwoodblues mentioned. The lesser recommendation in manual is a hand pump. I have a mk5 hill pump with only a pre filter like Alan shows here. (the dissicant and some orange beads that turn green when needed to be exchanged.) I think it is very effective, and an excellent idea, but I don't think it is a wise choice as a stand alone on a compressor!! Unlike your analogy the air filter on a car is for dirt not water and as we all know water comes out of a cars exhaust bc HEAT from combustion makes water from the air. Put that filter contraption on said automobile and I guarantee water will still come out of that exhaust. The air filter in the exhaust would do almost nothing for the water situation either.... Therefore I pump my hill slowly to save o-rings and cause less heat and therefore liquid water to the gun. I prefer Atlas Airguns method - do your best to keep the air dry and don't stress about the rest. Never gonna be 100% dry!

 

[Alan]

Real world truth: Never gonna be 100% dry!

The whole idea is to remove excess moisture. What one considers an excess is a manner of opinion. As long as there isn't any seal leakage, recompressing nitrogen is certainly one way to reduce the amount of moisture. Of course this assumes the tank of "dry nitrogen" is indeed dry. Nitrogen doesn't retain moisture, but during the separation of nitrogen from the air and pumping it into high pressure tanks, can indeed induce moisture. This, even if great lengths are taken to remove all of the moisture from "dry nitrogen"! As alluded to, is will never be 100% dry!

One advantage nitrogen has, with respect to airguns, is the fact it is less dense than the "air" we breathe. This allows for faster velocity vis-a-vis the volume of gas used. Whether its use provides longer airgun and/or seal life, is again a manner of opinion.

 

[AtlasAirguns]

Real world truth: Never gonna be 100% dry!

The whole idea is to remove excess moisture. What one considers an excess is a manner of opinion. As long as there isn't any seal leakage, recompressing nitrogen is certainly one way to reduce the amount of moisture. Of course this assumes the tank of "dry nitrogen" is indeed dry. Nitrogen doesn't retain moisture, but during the separation of nitrogen from the air and pumping it into high pressure tanks, can indeed induce moisture. This, even if great lengths are taken to remove all of the moisture from "dry nitrogen"! As alluded to, is will never be 100% dry!

One advantage nitrogen has, with respect to airguns, is the fact it is less dense than the "air" we breathe. This allows for faster velocity vis-a-vis the volume of gas used. Whether its use provides longer airgun and/or seal life, is again a manner of opinion.

When people use dry nitrogen it is effectively inert meaning the quantities of water vapor are so infinitesimally small as to not matter (or ever physically register) in our industry. Rust occurs from Oxygen not nitrogen - ferrous oxide. Most industrial supply of dry nitrogen are able to produce it typically less than 5 parts per million in moisture (usually 2-4) with a dew point of -86°F or 0.0187%RH. If we took an average of 3ppm for dry nitrogen, moisture present is around 0.000003% (incredibly dry) whereas air from the atmosphere can vary (again temperature dependent) between .2-4% - so we are talking astronomically higher amounts of moisture/water vapors in breathable air taken from atmosphere. The arrest of rust etc in airguns can be done with dry nitrogen because it is relatively inert (less than 5 parts per million and not tens of thousands of parts per million at atmosphere!).

The comparison between dry, breathable air and dry nitrogen in moisture present is the difference between the Niagra Falls and the Sahara Desert in laymen's terms.

 

[elwoodblues]

The other thing that using Nitrogen does for you No Detonation in compressors or guns and that is the main killer of these hpa compressors

 

[Alan]

That depends on the compressor. And dare I say, Cheap Chinese compressors? As least, every HPA compressor explosion I've heard about, were all CCC with the last 'C' not meaning compressor!

 

[bchannell]

I'm gonna go out on a limb here and say...all this depends on where you live and where you fill your airguns. I live in WV, not a super humid environment til July or Aug, so I wouldn't go outside with my compressor and pump up a rifle during those months. I do it in an air conditioned garage. If I am not using n2, then I have a molecular sieve filter on the outlet. Even without the filter I used to open air cylinders from my guns and no moisture damage at all, ever. It's a matter of mitigating not elimination and used common sense. As far as oil and debris, I use a cotton filter on the inlet and outlet to catch any crud, but it's not much of a concern with the GX.
I do HVAC work and always have n2 around so I use it in all my pcp guns, no moisture, no worry.

I worked I the chemical industry for 34+ years and still consult. N2 is, for most all chemical proses es, considered inert. I know the technical details, but that is a rare chemical exception. If you don't believe me, then we would have blown up literally thousands of highly volitile reactions if not for n2 buffering.

 

[elwoodblues]

I live north of Seattle and most days the humidity is around 90%, today it was 36F and 94% humidity No pre filter would remove that amount of moisture

 

[AtlasAirguns]

I live north of Seattle and most days the humidity is around 90%, today it was 36F and 94% humidity No pre filter would remove that amount of moisture

Most places that turn cold for winter have the same humidity as summer you just don't feel it is all.

 

[alamogunr]

Apologies for resurrecting this thread but I'm trying to assemble a pre-dryer for my Omega Air Charger. The discussion has been very informative but at this point in my beginning journey into PCP air guns, the finer details are a little over my head. While some say that Pre-Drying is not as good as Post-Drying, it is a good start for me.

The main problem I'm having is finding fittings that will fit the air intake on the compressor. I'm not sure how to specify the tube fittings that I will need adapting to the existing air intake. Todd with Omega informed me that the threads were metric but he didn't know the exact size. The small town I live in doesn't have a source of metric fittings. I'm not sure the employees at Ace Hardware, Lowe's or Home Depot would be able to help either. The major parts(cylinders for desiccant, fittings for the cylinders) I can get from Amazon.

Can anyone help me with the information that I need?

 

[Alan]

It is metric, and if yours is like the one I once had (Original Air Charger), it is 10x1. That is, 10 mm thread, 1 pitch. If you use the 1/2" OD hose and fitting to match, the inside diameter of the hose will be 3/8". This is a loose fit over any of the 10x1 fittings (ell perhaps), a small spring-type hose clamp will sufficiently seal the hose to the fitting. There is only a small vacuum present, so a billy-tight seal isn't needed here. Ace, Home Disappointment, et. al. should have the correct hose and fittings for the filter housing.

Let's talk about post vs pre drying. The medium used in almost all post dryers is 3A molecular sieve material. It looks like small balls of ceramic, of light ecru color. While they'll hold much more water than silica gel, there is no indication of how absorbed they are, even if you could look at one through some sort of quartz window. As a result, most lose their absorption ability well before they're replaced, or even thought about replacing! And run-time meters will not give you an adequate replacement gauge due to variances in local moisture ambients. This says nothing of the costs involved.

The advantage of using the two materials as outlined, is simply this. Once the 3A sieve has reached its fill, the silica gel will start to change color, telling you—"I need recharging!" I don't know, but I'd bet folks who say pre drying is any good, do not have the lab equipment to measure moisture content of the air they're compressing, post or pre dried.

 

[bchannell]

This is just me, but I'd focus on outlet filtering. I read a lot and there does seem to be a lot of evidence that pre filters don't do a lot of good. It's also easy to buy a fairly cheap and large outlet filter with cartridges. The problem remains knowing when to change filters. There just isn't a good info on how to judge. So, again, if it were me, I'd use an outlet filter, keep my filling line below the gun at all times, and change the filter ever couple months. Also, I would open the compressor, and more importantly the guns cyl, every few months to check for any sings of moisture. That's the only way I know of to be sure. You can adjust you maintenance timing based on what you see in the compressor and rifle cylinder.

I just don't want to fool with all that, so I use N2 at the compressor inlet, and then I can shoot more and maintain less. I've been doing it now for a few months and when I opened the compressor it was clean and dry on the outlet. Before, when using filters on the outlet and pumping air, it had quite a bit of rust and signs of moisture in the relief valve block of my compressor and it other fittings.

 

[rcs9250]

This is just me, but I'd focus on outlet filtering. I read a lot and there does seem to be a lot of evidence that pre filters don't do a lot of good. It's also easy to buy a fairly cheap and large outlet filter with cartridges. The problem remains knowing when to change filters. There just isn't a good info on how to judge. So, again, if it were me, I'd use an outlet filter, keep my filling line below the gun at all times, and change the filter ever couple months. Also, I would open the compressor, and more importantly the guns cyl, every few months to check for any sings of moisture. That's the only way I know of to be sure. You can adjust you maintenance timing based on what you see in the compressor and rifle cylinder.

I just don't want to fool with all that, so I use N2 at the compressor inlet, and then I can shoot more and maintain less. I've been doing it now for a few months and when I opened the compressor it was clean and dry on the outlet. Before, when using filters on the outlet and pumping air, it had quite a bit of rust and signs of moisture in the relief valve block of my compressor and it other fittings.

I guess the best argument for pre-drying is like the evidence you saw by using N2. That in itself is excellent, especially in places with high humidity. But I’m going to guess the expense of a N2 set up is going to discourage a lot of folks even though it would eliminate all pre or post drying equipment.

 

[elwoodblues]

The other thing everyone forgets is NO oxidizers with N2 there is no chance of detonation in the compressor or your guns as a bonus your gun will shoot slightly faster than air as its a smaller molecule with a lower molecular weight and size btw Co2 is not good for your gun either

 

[Danman]

The other thing everyone forgets is NO oxidizers with N2 there is no chance of detonation in the compressor or your guns as a bonus your gun will shoot slightly faster than air as its a smaller molecule with a lower molecular weight and size btw Co2 is not good for your gun either

Running your pcp on c02 is like running your gas car on propane, You just lost some HP...but it's bad for your gun? How so if I may ask?

 

[alamogunr]

It is metric, and if yours is like the one I once had (Original Air Charger), it is 10x1. That is, 10 mm thread, 1 pitch. If you use the 1/2" OD hose and fitting to match, the inside diameter of the hose will be 3/8". This is a loose fit over any of the 10x1 fittings (ell perhaps), a small spring-type hose clamp will sufficiently seal the hose to the fitting. There is only a small vacuum present, so a billy-tight seal isn't needed here. Ace, Home Disappointment, et. al. should have the correct hose and fittings for the filter housing.

Let's talk about post vs pre drying. The medium used in almost all post dryers is 3A molecular sieve material. It looks like small balls of ceramic, of light ecru color. While they'll hold much more water than silica gel, there is no indication of how absorbed they are, even if you could look at one through some sort of quartz window. As a result, most lose their absorption ability well before they're replaced, or even thought about replacing! And run-time meters will not give you an adequate replacement gauge due to variances in local moisture ambients. This says nothing of the costs involved.

The advantage of using the two materials as outlined, is simply this. Once the 3A sieve has reached its fill, the silica gel will start to change color, telling you—"I need recharging!" I don't know, but I'd bet folks who say pre drying is any good, do not have the lab equipment to measure moisture content of the air they're compressing, post or pre dried.

Not sure that the highlighted sentence expresses the intended thought accurately. So far no one has explicitly said that pre-drying is better than doing nothing. Does that mean that if I don't want to go to post-drying or N2 that I'm better off doing nothing?

 

[elwoodblues]

The Co2 I was talking about is the percent in air the dioxide part is corrosive.
hat is the effect of CO2 on steel?


The corrosion rate increased further to 0.5604 mm/year at the CO2 partial pressure of 70 bar. The highest corrosion rate of 0.7806 mm/year was obtained at supercritical CO2, i.e. 95 bar, concluding that an increase in CO2 pressure increases the corrosion rate of carbon steel.

 

[AtlasAirguns]

Not sure that the highlighted sentence expresses the intended thought accurately. So far no one has explicitly said that pre-drying is better than doing nothing. Does that mean that if I don't want to go to post-drying or N2 that I'm better off doing nothing?

If you read the above comments from the beginning, the science is pretty resolute. What gun are you shooting btw?