Tank Adapter / Bulkhead Adapter

thingiverse

Tank Adapter for Connecting Rain Barrels to NPT Pipe Fittings. A few years back, I converted a used 220-liter pickle barrel into a rain barrel. As my vegetable garden expanded, a single barrel of water couldn't last more than a few days without rain. The simple solution was to add more barrels. After purchasing two more barrels, I discovered that the tank adapter was no longer available at my local hardware store and the cost on Amazon was $45 or more. Since I needed two adapters for each new barrel plus one for the existing barrel, the cost became quickly prohibitive. After hours of work with OpenSCAD and a few hundred meters of filament for tests and prototypes, here is a serviceable tank adapter. Cost is under $5. You will need to print (in PETG or ABS): 1 x tank_adapter 1 x tank_adapter_nut and (in TPU): 1 x tank_adapter_seal The tank adapter and nut are best printed in PETG. It has excellent layer adhesion, durability, and heat tolerance. ABS can also be used. Because the material properties and shrinkage are a bit different from PETG, there is a version of the tank adapter nut especially for ABS. Just make sure you print both the tank adapter and the nut with the same material. The seal requires flexible material. I used black TPU. The tank adapter comes in two sizes. One for 3/4" NPT pipe fittings and one for 1/2". Both use the same nut and seal. Use a 1 5/8" hole saw to make the hole in the barrel. It is designed for a wall thickness up to about 1/4". Installation is straightforward: 1. Place the seal over the threads on the tank adapter. Ensure that the bevelled side of the seal is facing the bevelled surface of the adapter. 2. Apply Teflon plumbers tape to the adapter threads. This helps ensure a good seal and also prevents the threads from binding or jamming. 3. Push the tank adapter through the hole in the barrel from the inside. 4. Carefully holding the adapter, place the nut onto the threads and tighten by hand. 5. Apply Teflon plumbers tape to the threads on the faucet (tap) or other NPT fitting. 6. Screw the fitting into the tank adapter. Again, only tighten by hand. Do not over tighten, remember that PETG or ABS is a lot softer than the brass or steel the faucet is made from. CAUTION: HAND TIGHTEN ONLY This should be sufficient to form a water-tight seal. Wetting the seal (or the barrel wall) before installation helps. If there is still some seepage, leave the parts for 24 hours to settle in and tighten again by hand. Using a wrench, spanner or other leverage on the nut or adapter should not be necessary and may weaken the adapter. Be very careful if you do. NPT thread library from https://dkprojects.net/openscad-threads/