Four Uncles PCP Pump Moisture Filter

A moisture filter designed for the four uncles PCP hand pump and maybe some other chinese ones that have the same top dimensions

Each time you pump without using any moisture filter a very small amount of water gets into the air reservoir of your airgun. Over time it could lead to internal corrosion in the regulator or other steel parts, which is bad and lowers the lifetime of your cylinder, which must not be harmed.

It does not need any extra hardware since it uses the screws the pump already uses to mount the handlebars.

However, it needs a desiccant to work, and I reccommend buying 3A molecular sieve as it absorbs moisture very fast and gets it to nearly 0% humidity. 

Amazon link to the one I bought ($20): https://www.amazon.com/Wisesorb-Molecular-Desiccant-Dehumidifier-Absorbers/dp/B09QGM9X7G/

Print in PLA or some filament that you have settings really dialed in for overhangs and dimensional accuracy or else it will not work or fit, it does not have to be anything strong since the part will not bear any load. Do NOT use supports or it will not allow air to go through the chamber well and remove the moisture.

Assembly

1. Get the filter without the fins on it and push it to the bottom of the main body through the top rectangular hole with something long like a screwdriver. 

2. Take off the rubber grips on the pump

3. Unscrew the bolts holding the metal grip 

4. Slide the print in the middle, making sure the holes line up. 

5. Reassemble the grip stuff

6. Dump desiccant into the tube area

7. Then put the top thing on. Put a rubber band on like shown in image so when storing or pumping the filter will not pop out and spill the little balls everywhere. It took forever to clean up when it  happened to me :D

8. Pump upwards a little slower than normal to allow more moisture to be pulled out the air. You don't need to go too slow though.

When storing use the top with fins that does NOT have slits and when pumping use the top with fins that has the slits.

The top covers in the image only have one wing thing since I tried it like that first but it was harder to take off so I modeled it to have two but never bothered to print it.

Replace the desiccant every so often so it works optimally. If you are just topping off say 2000->3000psi a 100cc tube and humidity is 80% it could last around 40 fills before saturating.

If you are using the sieve, save it so once you run out you can reuse it by heating it in the oven and setting it to the highest or at 480F (250C) if your oven can go that high and bake for 4-8 hours, depending on how saturated it is. Let it cool slowly in a airtight container so it wont start reabsorbing again until you want to use it.