Dry Air for Hand Pump or Compressor
I have been using a hand pump with a dry pack but when cleaning the gun I always noticed moisture drops in the air chamber. In an attempt to get drier air for my gun I came up with a very effective and inexpensive way to get all the dry air I need. All I needed was 1) 20′ coil of 1/4 ” flexible copper tubing ($9) 2) plastic tubing ($2.65) and 3) a brass fitting ($3.50) all of which can be found at Home Depot. See attached photo. Bend the tubing so the coil can be hung in a chest freezer with the incoming and out going tube bent so it can be accessed from outside the freezer. Hang the coil in the freezer for about 15 minutes before you pump to get it good and cold. I add a 5lb weight to the top of the freezer to ensure the freezer lid seals tight. I pump a dozen strokes to get the humid air out of the line before I hook it up to the gun and start pumping. External humid air going through the coil will be chilled to about 0 – 5 degrees F. Moisture in the air will condense out and form crystals in the tube and only very dry air will emerge from the outgoing line. I calculate that emerging air will be at about 10% humidity at room temperature. This is about 4x drier that commercial SCUBA air. After you are done pumping remove the coil, let it warm up and run a blast of compressed air through it to get rid of all the accumulated moisture. For those who do not have access to a chest freezer you could fill a 12″ piece of PVC pipe with glass marbles with an input hole at one end and a plastic tube at the other. Put the pipe with the marbles in it in your freezer and get it cold. Then take it out of the freezer, wrap it in a towel to keep it from getting warm to quick and start pumping. There should be plenty of cold and surface area in the pipe to strip out most of the moisture. Just remember to let it dry before using it again. There are a number of other variations but you get the idea. I thought others might find this useful. Suggestions on improvements are welcome.
Happy hunting!
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Viewing 10 replies - 1 through 10 (of 10 total)
My pump does not have a fitting for filtration. Any ideas?
Steel ball bearings should work better than glass provided they do not rust. I am not sure you need the cooler with ice. Most freezers cool to about 0 – 5 degrees F and that should keep everything cold enough to fill a PCP. Try it. It will be easy to tell if you need the ice.
PS – I also added a dense cotton ball behind the brass fitting I added to the pump to serve as a air filter.
Now you got me thinking………….LOL
3″ PVC pipe, one end cap with a nipple for the tubing, the other with a cap and some breather holes drilled into it – filled with steel ball bearings – frozen in the freezer – then slide it into one of those little styrofoam coolers that has holes drilled through both sides that the 3″ pipe fits in with the end caps sticking out the ends – fill the cooler with ice – put in the lid & start pumping!
Yep – that’s what I’m going to do. I will post pictures when its together.
Thank you for the awesome idea!
Do you think steel ball bearings would hold cold longer than glass for the PVC tube method?
I have a bunch of 1/2″ glass ammo for my slingshot I bought in bulk by the pound. If you buy the Trumark brand name its like $5 for 72 pieces.
I bought 5 #’s (over 800 pieces) for like $20. Do a Google search for ‘bulk slingshot ammo’.
Is the ball bearing idea cost prohibitive?
KJ Magnetics has good steel ball bearing prices. That’s who I buy my 1″ ball bearings from to make my Monkey Fist necklaces.
What do you think?
Thanks! Looks like I will be getting some copper tubing. LOL
Its really humid where I live in the mountains of the Pacific Northwest – probably a good idea I do this PITA or not.
🙂
Or is this a low maintenance low cost long term option?
I like the idea, it just seems like a PITA.
Either way – Thanks! That’s thinking outside the box.
🙂
My primary goal was to get air so dry that NO moisture formed in the compressed air reservoir or around the reg. In humid weather the dry pack just could not strip out enough moisture. With this method I have never found even the smallest drop of moisture in the gun. The fact that it is low cost and low maintenance is an added benefit. You are right in that it is a bit of a PITA and it is not for everyone. However, I only fill up about once a week and knowing what I paid for my guns the extra effort is worth it.
It would have to be rated for the pressure of your fill. They are not cheap. Has a big cartridge inside it.
This is on my Sheldon compressor. 5000 psi grade E air.
I get the idea of cooling the air to keep it colder than the outside air temp and thus avoid condensation build up – but wouldn’t it be easier to just add an inline dry pack between the pump and bottle connection?
Or is this a low maintenance low cost long term option?
I like the idea, it just seems like a PITA.
Either way – Thanks! That’s thinking outside the box.
🙂
Great idea! Thanks for the post.
Viewing 10 replies - 1 through 10 (of 10 total)
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There’s an air intake hole somewhere. You can always drill it and tap it.
Make sure you completely disassemble the pump, complete deburring of the threaded portion and make sure NO metal shavings get inside anywhere.
I would just rebuild your pump with new seals since it will be apart already anyway.
Then you can install a threaded nipple to attach the hose to.