Source for Hand Pump Dryer/Desiccant Filter?

[RMM]

I wasn't entirely complete on my setup. Here is my airflow:
Outside air(14.7psi@sea level)>compressor @ 150spi>desiccant filter/regulator@25psi>desiccant filter on Benji pump>gun.
IMHO the first compression to 150psiby a compressor is very important as it removes a great deal of the moisture from the air. Then running that air thru desiccants further removes moisture and the desiccant will last much longer if most of the water is removed by a compressor first. Your large home made desiccant filter looks like it should do a great job. When it comes to desiccant....more is better.

Someone ask about acquiring desiccant crystals, Walmart sells it in a rather large container for about 12 bucks.
The desiccant can be dried in an oven and reused many times.

Great info for sure plus thank you for sharing your expertise as it is much appreciated. 

[dukja]

Thanks for the idea.  I knew that it is an old thread, but would like to provide a heads-up if someone want to do it DIY.

The thread on the inlet of the Benjamin pump is not EXACTLY 1/8" MIP (or NPT).  At least the recent one I got is not.  It is about 10 thousandth smaller and machinist suspect that it may be metric.  So if you are in US and go buy some 1/8" MIP barb adapter, it will NOT fit, unless you also buy a tap to enlarge the thread.

Alternatively, I have found some nylon/plastic 1/8" MIP with 1/4" barb adapter from Tractor Supply and it has about 5 thousandth smaller ID.  Plus it is more pliable and may be seal without change the existing thread.

Just a note, so others won't wasting a few hours running around to figure it out. 

[Muldune]

Thanks for the idea.  I knew that it is an old thread, but would like to provide a heads-up if someone want to do it DIY.

The thread on the inlet of the Benjamin pump is not EXACTLY 1/8" MIP (or NPT).  At least the recent one I got is not.  It is about 10 thousandth smaller and machinist suspect that it may be metric.  So if you are in US and go buy some 1/8" MIP barb adapter, it will NOT fit, unless you also buy a tap to enlarge the thread.

Alternatively, I have found some nylon/plastic 1/8" MIP with 1/4" barb adapter from Tractor Supply and it has about 5 thousandth smaller ID.  Plus it is more pliable and may be seal without change the existing thread.

Just a note, so others won't wasting a few hours running around to figure it out. 

Thank you for that information it may be very useful very soon for me.

[Doug Wall]

I was under the impression you get the moisture when you compress the air so does putting the filter on the intake really help?

       1st you need to understand Relative Humidity and how water vapor behaves. All air has some water vapor in it. (even the compressed air you buy) RH is the amount of water vapor in the air relative to the max it could hold at it's temperature and pressure. So 50% RH tells you the air contains half the amount it could hold. 100% is saturated air and it can't hold any more. When you take air and compress it to 100% the air will be at the Dew Point. DP is the point that water vapor will/must condense into liquid. Every cloud in the sky is at this point. So when it happens in a vessel like a tank....condensation must occur. Water always condenses on something. In the clouds it condenses on particles of dust, smoke and pollen.  In a tank...it condenses on the tank.
     Water vapor in air behaves a lot like liquid water in a sponge. When you take a sponge with the available spaces half full of water (50%) and squeeze (compress) the sponge till there are no empty spaces, the water will start coming out of the sponge.
 
        When you run air thru the compressor.....it is the first water removal for the air. Then when you take that air which has a lot less water in it and run it thru desiccant crystals, they remove even more of the water from that air.
       If the pump then takes that air and compresses it to the dew point more water will condense in the pump and when you depressurize the pump to remove it from the gun, you will see water exhausted from the pump. Using my boosting method I never see water come from my pump or see grey grease that has water in it. That tells me that the air I am moving into the gun is not at the dew point and therefore is very dry.
       Once air is in the gun and you lower the pressure by shooting the gun, the RH of the air in the gun will do nothing but go down with each shot as you depressurize the reservoir on the gun. So long as the RH is low enough that liquid water is not condensed on the metal, no corrosion can be formed.
       I hope this has not been too scientific for understanding. I've only been a scientist for over 40 years.
PS if you buy your air compressed already, and you believe that there is no water in that air you bought at the scuba shop or paint ball park or fire station, you are wrong. It's almost impossible to remove all the water from air. It's only dry enough to cause no condensation in your gun, that's all. 

Good summary! I'll add that the larger the dessicant container, the better. Air doesn't magically lose the moisture instantly by contacting the dessicant, it has to stay in contact for a while. In a small filter, the air may only be in there for a pump stroke or two, not enough time to take the moisture out. In a much larger container, the air will be in there for much longer.