Others Pre dryer

[Bob1]

Most PCP users have some sort of high-pressure pump to refill their airguns and/or portable tanks. Most have some sort of device to trap or absorb moisture in the compressed air column. Higher end units might be equipped with high pressure post filters. The former ones are very inefficient, and require regular replacement of the (treated?) filter cartridge. The latter ones have two drawbacks. The filter cartridges are expensive (≈$20 each), and you can’t tell if they’re still being effective. Further, the extra volume they contain requires pressurizing before your airgun starts to refill. Read that as extra wear and tear on the pump. But there is an alternative, and that is a pre dryer.

View attachment 701The photo shows one I put together. I won’t make apologies for the photo, because form always follows function! The filter housings may be purchased from Amazon https://www.amazon.com/YOEDAF-Housi...prefix=empty+filter+cartridge,aps,134&sr=8-32 for under $15 each. The half inch fittings and plastic tubing are available from Ace Hardware, Home Depot, and Lowes. The filter’s outlet hose is fed into the inlet fitting on my Hill EC-3000 compressor. But it isn’t the housings which make the filter unique, it is what’s in them!

The right one is filled with 3A Molecular Sieve material, an industrial desiccant. It too may be purchased from Amazon (https://www.amazon.com/Wisesorb-Pre...-2-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&psc=1 The 3A refers to the molecular size it can absorb, and in this case, water vapor. In fact type 3A Molecular Sieves will reduce water in an air stream to 0.001 mg/liter air. Read that as very effective. However, like post dryers, you can’t tell when it can no longer absorb moisture. There is solution!

The left housing is filled with Silica Gel, another industrial desiccant. In this case, the Silica Gel changes color as it nears its limit of trapping moisture. Once the blue color (there are other colors available) changes to pink, you know it is time to recharge it. And here is how that is done.

For the record, 3A Molecular Sieve material can also be recharged. Unfortunately, the necessary equipment is rather expensive and cumbersome. So it is cheaper to toss it out (it’s environmentally safe to do so). The Silica Gel, on the other hand, can be easily recharged in a microwave oven. Fill up a Mason jar full of Silica Gel, and heat for about 1.5 minutes on high power. Be careful, it will be HOT! Take it out of the microwave, and allow the remaining moisture to evaporate. Once cool, put the lid back on and save for the next recharge.

All of this “stuff” will set you back about $75 depending on the quantity of desiccant you buy. A gallon jug of 3A Molecular Sieve is about $35 (about 10 refills). The reusable Silica Gel is about $10 for a quart jar full.

The bottom line? The setup is indeed effective! I shoot about 300 rounds a week, which is about 8 refills (120 BAR back up to 250 BAR). The pre dryer has had about 10,000 rounds worth of air drawn through it, and I’ve only needed to change the 3A Molecular Sieve material once! And, the best part is, when I open the air bleed valve, no moisture is expelled!

Most PCP users have some sort of high-pressure pump to refill their airguns and/or portable tanks. Most have some sort of device to trap or absorb moisture in the compressed air column. Higher end units might be equipped with high pressure post filters.

I realize this is an older thread. I am new to PCP air gunning and am just setting up/ordering the stuff I need to charge my rifle. I am in humid Florida and this looks like good extra protection against moisture in my compressed air.

What stops the media from falling out the bottom of the containers?

 

[Roamin Greco 1]

Most PCP users have some sort of high-pressure pump to refill their airguns and/or portable tanks. Most have some sort of device to trap or absorb moisture in the compressed air column. Higher end units might be equipped with high pressure post filters. The former ones are very inefficient, and require regular replacement of the (treated?) filter cartridge. The latter ones have two drawbacks. The filter cartridges are expensive (≈$20 each), and you can’t tell if they’re still being effective. Further, the extra volume they contain requires pressurizing before your airgun starts to refill. Read that as extra wear and tear on the pump. But there is an alternative, and that is a pre dryer.

View attachment 701The photo shows one I put together. I won’t make apologies for the photo, because form always follows function! The filter housings may be purchased from Amazon https://www.amazon.com/YOEDAF-Housi...prefix=empty+filter+cartridge,aps,134&sr=8-32 for under $15 each. The half inch fittings and plastic tubing are available from Ace Hardware, Home Depot, and Lowes. The filter’s outlet hose is fed into the inlet fitting on my Hill EC-3000 compressor. But it isn’t the housings which make the filter unique, it is what’s in them!

The right one is filled with 3A Molecular Sieve material, an industrial desiccant. It too may be purchased from Amazon (https://www.amazon.com/Wisesorb-Pre...-2-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&psc=1 The 3A refers to the molecular size it can absorb, and in this case, water vapor. In fact type 3A Molecular Sieves will reduce water in an air stream to 0.001 mg/liter air. Read that as very effective. However, like post dryers, you can’t tell when it can no longer absorb moisture. There is solution!

The left housing is filled with Silica Gel, another industrial desiccant. In this case, the Silica Gel changes color as it nears its limit of trapping moisture. Once the blue color (there are other colors available) changes to pink, you know it is time to recharge it. And here is how that is done.

For the record, 3A Molecular Sieve material can also be recharged. Unfortunately, the necessary equipment is rather expensive and cumbersome. So it is cheaper to toss it out (it’s environmentally safe to do so). The Silica Gel, on the other hand, can be easily recharged in a microwave oven. Fill up a Mason jar full of Silica Gel, and heat for about 1.5 minutes on high power. Be careful, it will be HOT! Take it out of the microwave, and allow the remaining moisture to evaporate. Once cool, put the lid back on and save for the next recharge.

All of this “stuff” will set you back about $75 depending on the quantity of desiccant you buy. A gallon jug of 3A Molecular Sieve is about $35 (about 10 refills). The reusable Silica Gel is about $10 for a quart jar full.

The bottom line? The setup is indeed effective! I shoot about 300 rounds a week, which is about 8 refills (120 BAR back up to 250 BAR). The pre dryer has had about 10,000 rounds worth of air drawn through it, and I’ve only needed to change the 3A Molecular Sieve material once! And, the best part is, when I open the air bleed valve, no moisture is expelled!

I think this is a fascinating idea! Have any other HAMsters duplicated this and can we test this out to see whether it helps and by how much? Perhaps a chamber can be created between this system and the pump with a humidistat to measure the humidity of the air after the dessicants, compared to the humidity of the ambient air.

 

[Alan]

I'm surprised this thread is still active even though I'm not!

I have actually performed a non scientific test of sorts using humidity strips. They're like hot tub test strips but somewhat larger in size. The lowest they measure it 4% and the highest 80%. During an average day here in Roswell, the humidity varies quite a bit from 7% to 10% during the day, and around 50% to 70% at night.

I filled my portable tank up to 300 BAR using it as a source. I put one strip inside a mason jar with two holes in the lid—one in, one out. Didn't matter what the ambient humidity was, the stripe inside the mason jar never showed over the minimum 4% mark. Since the blue tinted silica gel turns pink once it becomes ≈40% saturated, it is easy to tell when the 3A molecular desiccant needs to be replaced.

I don't shoot as much as I used to, but I can refill the gun directly about 50 times, before I need to replace the desiccants. I reuse the silica gel by refreshing it in the microwave. I toss out the molecular desiccant as I don't own a 1,500° oven needed to dry it. Incidentally, the 3A molecular desiccant costs about $40 for 7 pounds (Amazon), and will refill the drying tube about 10 times.

 

[Zelos1]

Most PCP users have some sort of high-pressure pump to refill their airguns and/or portable tanks. Most have some sort of device to trap or absorb moisture in the compressed air column. Higher end units might be equipped with high pressure post filters. The former ones are very inefficient, and require regular replacement of the (treated?) filter cartridge. The latter ones have two drawbacks. The filter cartridges are expensive (≈$20 each), and you can’t tell if they’re still being effective. Further, the extra volume they contain requires pressurizing before your airgun starts to refill. Read that as extra wear and tear on the pump. But there is an alternative, and that is a pre dryer.

View attachment 701The photo shows one I put together. I won’t make apologies for the photo, because form always follows function! The filter housings may be purchased from Amazon https://www.amazon.com/YOEDAF-Housi...prefix=empty+filter+cartridge,aps,134&sr=8-32 for under $15 each. The half inch fittings and plastic tubing are available from Ace Hardware, Home Depot, and Lowes. The filter’s outlet hose is fed into the inlet fitting on my Hill EC-3000 compressor. But it isn’t the housings which make the filter unique, it is what’s in them!

The right one is filled with 3A Molecular Sieve material, an industrial desiccant. It too may be purchased from Amazon (https://www.amazon.com/Wisesorb-Pre...-2-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&psc=1 The 3A refers to the molecular size it can absorb, and in this case, water vapor. In fact type 3A Molecular Sieves will reduce water in an air stream to 0.001 mg/liter air. Read that as very effective. However, like post dryers, you can’t tell when it can no longer absorb moisture. There is solution!

The left housing is filled with Silica Gel, another industrial desiccant. In this case, the Silica Gel changes color as it nears its limit of trapping moisture. Once the blue color (there are other colors available) changes to pink, you know it is time to recharge it. And here is how that is done.

For the record, 3A Molecular Sieve material can also be recharged. Unfortunately, the necessary equipment is rather expensive and cumbersome. So it is cheaper to toss it out (it’s environmentally safe to do so). The Silica Gel, on the other hand, can be easily recharged in a microwave oven. Fill up a Mason jar full of Silica Gel, and heat for about 1.5 minutes on high power. Be careful, it will be HOT! Take it out of the microwave, and allow the remaining moisture to evaporate. Once cool, put the lid back on and save for the next recharge.

All of this “stuff” will set you back about $75 depending on the quantity of desiccant you buy. A gallon jug of 3A Molecular Sieve is about $35 (about 10 refills). The reusable Silica Gel is about $10 for a quart jar full.

The bottom line? The setup is indeed effective! I shoot about 300 rounds a week, which is about 8 refills (120 BAR back up to 250 BAR). The pre dryer has had about 10,000 rounds worth of air drawn through it, and I’ve only needed to change the 3A Molecular Sieve material once! And, the best part is, when I open the air bleed valve, no moisture is expelled!

Please post a simple schematic.

 

[Alan]

Please post a simple schematic.

Please post a simple schematic.

 

[Alan]

There really isn't one. The various pages list that the parts came from Amazon. The currently available housings are a bit different but function is the same. They have media filters in the end caps which keep the media in place. The plastic fitting can be ordered from Amazon of bought at any decent hardware store. The tubing is 1/2 " ID. The air passes through the 3A molecular media first, and then the silica gel. from there is goes to the air input fitting on whatever compressor you have. Although the silica gel is also a desiccant, in this case it also acts like an indicator telling you the 3A molecular media needs to be changed.

 

[Lowndes]

There really isn't one. The various pages list that the parts came from Amazon. The currently available housings are a bit different but function is the same. They have media filters in the end caps which keep the media in place. The plastic fitting can be ordered from Amazon of bought at any decent hardware store. The tubing is 1/2 " ID. The air passes through the 3A molecular media first, and then the silica gel. from there is goes to the air input fitting on whatever compressor you have. Although the silica gel is also a desiccant, in this case it also acts like an indicator telling you the 3A molecular media needs to be changed.

Hey, Alan. Any particular reason to put the silica gel filter after the molecular sieve filter??

 

[Alan]

Yes, You can't tell when the sieve is saturated. Once it is, the moisture is collected by the silica gel, when turns from blue to pink.

 

[Dwildemn]

Most PCP users have some sort of high-pressure pump to refill their airguns and/or portable tanks. Most have some sort of device to trap or absorb moisture in the compressed air column. Higher end units might be equipped with high pressure post filters. The former ones are very inefficient, and require regular replacement of the (treated?) filter cartridge. The latter ones have two drawbacks. The filter cartridges are expensive (≈$20 each), and you can’t tell if they’re still being effective. Further, the extra volume they contain requires pressurizing before your airgun starts to refill. Read that as extra wear and tear on the pump. But there is an alternative, and that is a pre dryer.

View attachment 701The photo shows one I put together. I won’t make apologies for the photo, because form always follows function! The filter housings may be purchased from Amazon https://www.amazon.com/YOEDAF-Housi...prefix=empty+filter+cartridge,aps,134&sr=8-32 for under $15 each. The half inch fittings and plastic tubing are available from Ace Hardware, Home Depot, and Lowes. The filter’s outlet hose is fed into the inlet fitting on my Hill EC-3000 compressor. But it isn’t the housings which make the filter unique, it is what’s in them!

The right one is filled with 3A Molecular Sieve material, an industrial desiccant. It too may be purchased from Amazon (https://www.amazon.com/Wisesorb-Pre...-2-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&psc=1 The 3A refers to the molecular size it can absorb, and in this case, water vapor. In fact type 3A Molecular Sieves will reduce water in an air stream to 0.001 mg/liter air. Read that as very effective. However, like post dryers, you can’t tell when it can no longer absorb moisture. There is solution!

The left housing is filled with Silica Gel, another industrial desiccant. In this case, the Silica Gel changes color as it nears its limit of trapping moisture. Once the blue color (there are other colors available) changes to pink, you know it is time to recharge it. And here is how that is done.

For the record, 3A Molecular Sieve material can also be recharged. Unfortunately, the necessary equipment is rather expensive and cumbersome. So it is cheaper to toss it out (it’s environmentally safe to do so). The Silica Gel, on the other hand, can be easily recharged in a microwave oven. Fill up a Mason jar full of Silica Gel, and heat for about 1.5 minutes on high power. Be careful, it will be HOT! Take it out of the microwave, and allow the remaining moisture to evaporate. Once cool, put the lid back on and save for the next recharge.

All of this “stuff” will set you back about $75 depending on the quantity of desiccant you buy. A gallon jug of 3A Molecular Sieve is about $35 (about 10 refills). The reusable Silica Gel is about $10 for a quart jar full.

The bottom line? The setup is indeed effective! I shoot about 300 rounds a week, which is about 8 refills (120 BAR back up to 250 BAR). The pre dryer has had about 10,000 rounds worth of air drawn through it, and I’ve only needed to change the 3A Molecular Sieve material once! And, the best part is, when I open the air bleed valve, no moisture is expelled!

Great design - I will make mine this cold winter and be ready for the spring.

 

[Lowndes]

Yes, You can't tell when the sieve is saturated. Once it is, the moisture is collected by the silica gel, when turns from blue to pink.

OK. That makes sense. Thanks.

I'm setting up a prefilter system. For the last 6-8 years I was using nothing but N2 because there was a paintball shop around the corner from my house and they would fill my little CF tanks for free. That was great while it lasted and spoiled me and my PCP's. Then they closed. Bought a little Vevor pump and got worried about the condensate issue. Ordered the housings, SG and 3A someone put a link to (Thank You) and I did some online searching to find out more about the 3A and SG. From all the info available it will take someone a lot smarter than me to figure out which media will leave the least moisture, but I think it might be the 3A.

BTW, I did find this online:
"Type A have three grade 3A, 4A and 5A and type x have 13 X having a pore diameter of 10 Angstrom....", and more here: How much moisture can molecular sieve adsorb?.

Your 4% moisture test strips are a brilliant idea. I'm thinking about some way to put one in the clear plastic tubing between the last media chamber and the pump intake to make it visible full time, just like the SG. Just don't need the strip sucked into the pump.

I've not found any 4% test strips but I did find 5% reversable cards:
https://www.digikey.com/en/products...iBhZ7_TyEjZR5zna7QQvxcM21KJzQFEoaApnYEALw_wcB

The weak link now is the connection to the air pump itself. There is a small plastic cage with a filter about the size of the last joint of your little finger that threads into the head of the pump. The thread is 9 mm OD (6.3 mm ID) but cannot determine the pitch, doesn't match anything I can find. So I just stuck the tube on it for now.

 

[Bob1]

OK. That makes sense. Thanks.

I'm setting up a prefilter system. For the last 6-8 years I was using nothing but N2 because there was a paintball shop around the corner from my house and they would fill my little CF tanks for free. That was great while it lasted and spoiled me and my PCP's. Then they closed.

Would it not have been easier and cheaper to just continue with N2? A tank and a regulator is not all that much money. At least around here it is not. With the N2 you do not have to worry about being smart enough to calculate all the moisture data. Zero moisture is zero no matter how it is calculated.

 

[Lowndes]

Bob1, you may be totally correct, except the part about cheaper. I looked into it several years back and the initial cost, tank, reg, etc was substantial. Also, I never do anything the easy way it seems. Totally out of character for me. But, I am cheap.

I might look around for a used tank/reg, see what's available now.

 

[Lowndes]

As I indicated in an earlier post, I ordered the things I needed to build a pre-drier as shown in the first post of this thread. The biggest problem I had was finding a fitting to connect tubing to the input of the compressor. No one knew the thread size of the existing fitting. Alan thought it might be M10-1. His compressor may have that thread size but what I received was obviously too small. Also as I mentioned earlier, When I checked at Lowe's thread checker, I determined that it might be M14-1.5, so I ordered that size. When I received them, they DID NOT FIT. These got returned to Amazon. In the meantime the rest of my order was delivered which included plastic tube fittings that were correct for the filter housing. Turns out they were also correct for the air input to the compressor. Checking back to the size I ordered, It is 1/4 NPT X 3/8 Tube OD. (Amazon.com)
I can't explain why the M14 fittings didn't work.

Now that I have everything needed, I'll try to put it together in the next few days. I'm no good at posting pictures but since I'm using the picture Alan posted as a guide, I'm sure that you get the idea.

Hey, Alamogunr. I'm having the same problem with the input thread on my compressor, a VEVOR ss-pac03a. There was a small inlet filter threaded into the hole which helps when measuring the diameter and pitch. The threads did not match anything I have in metric, UNC, UNF, or Schrader. This pump is made in China so it would most likely be metric. My caliper measures the major diameter at 9.00 mm, 23/64 in and 0.354 in. My thread gauge is a perfect fit at 0.9 (metric) AND 28 tpi. It sure does measure out to be an M9 x 0.9, but I can not find anything with that thread online, just a reference to it for small pneumatic and hydraulic lines.

 

[Lowndes]

I thought about this at lunch and googled it:

do desiccants like silica gel and molecular sieve work better with higher or lower pressure or air velocity

This is what came back (from AI??):

Desiccants like silica gel and molecular sieves work best with lower air velocity for longer contact time but perform differently with pressure; silica gel prefers low pressure, while molecular sieves handle higher pressures better, especially at low humidity, but both need optimal flow for efficiency, avoiding extremely high velocities that reduce moisture transfer.

This information favors a slightly different setup than anyone has mentioned here, I believe. This setup would be to use a silica gel on the intake side (low pressure) of the pump and the molecular sieve on the discharge (high pressure). To get the velocity lower on the intake side, parallel filters could be used.

Any thoughts here??

 

[Danman]

I thought about this at lunch and googled it:

do desiccants like silica gel and molecular sieve work better with higher or lower pressure or air velocity

This is what came back (from AI??):

Desiccants like silica gel and molecular sieves work best with lower air velocity for longer contact time but perform differently with pressure; silica gel prefers low pressure, while molecular sieves handle higher pressures better, especially at low humidity, but both need optimal flow for efficiency, avoiding extremely high velocities that reduce moisture transfer.

This information favors a slightly different setup than anyone has mentioned here, I believe. This setup would be to use a silica gel on the intake side (low pressure) of the pump and the molecular sieve on the discharge (high pressure). To get the velocity lower on the intake side, parallel filters could be used.

Any thoughts here??

Very interesting! I run a Hill Handpump and their compressor. Love the brand, but they alternate on their filtering...even they are confused possibly?
Hand pump: Dessicant beads and color changing silica beads on intake side only. Visual aid and dryer air....supposedly.
My Compressor runs a decent sized in-line oem filter with carbon filters, Dessicant beads, and the cotton (?) cigarette style filter...no silica beads.

Guess what? Moisture issues in the hand pump.
With heavy usage those beads didn't keep up. (Changed em out twice a year and used pump in house only) I added an inline filter after that. I think forcing air over either would be better than a pre filter. Lastly....I guess running color changing beads inside your in-line filter may be useless as you wont be able to see em without opening it up.

 

[Lowndes]

Here's more info on the desiccants from Google:

which desiccant media, silica gel or Molecular sieve will remove the most moisture from air and at what flow rates and pressuresx]??

Reply:

"Molecular sieve removes the most moisture, achieving much lower dew points (even below -100°F) by capturing water in precise pores, excelling at low relative humidity (RH) and high temperatures, while silica gel is better for moderate, higher RH (20-90%) and offers energy-efficient regeneration but struggles at extreme low humidity and high temps where it can release moisture, making sieves superior for deep drying, though both benefit from flow/pressure optimization."

So this info alo points to silica gel in a pre filter and Mol Sieve in a discharge (pressurized) filter. The flow rate in the discharge will be much lower than the intake, the same quantity of atoms/molecules going in and out of the pump, just in a much smaller "package" (CFM) in the discharge. i.e. use the silica gel in an easy to get at and service pre filter to get most of the water out, then after it is pressurised, use the Mol Sieve where it works best to get the last bit of moisture out.

I'm seriously considering this type setup for my VEVOR pump, unless someone maybe sees this differently. ??

 

[Centerfire]

My compressor is a Hill EC-3000. The inlet air filter, if you can call it that, looks and feels like a dental dam. It has more back pressure than the pre dryer.

By the way, I used this for several years on an Omega Charger, and now about three years on the Hill. No issues whatsoever ever!

Alan, I too have a Omega Air Charger that I have added a Omega Coltri air dryer. It has desiccant and charcoal in a plastic tube with a piece of blue tape to watch for color change. The system operates at over 145BAR which is the inlet valve opening on my air rifle tube.
I think the Wisesorb 3A molecular sieve desiccant might be the correct item to use to replace the beads in the unit now. Comments please