Inspect your reusable, empty propane cylinder with a 5-lb. capacity thoroughly for damage. Pay special attention to dents, bulges, cracks and rusted or pitted areas. Also ensure the cylinder has its foot ring, cylinder collar and valve cover.
Freeze the empty propane cylinder for 15 minutes, or pull the pin off the pressure-relief valve. That will ensure that the pressure is different between the empty cylinder and a full cylinder, which promotes optimal filling.
Remove the empty cylinder's valve cover. Attach a propane tank adapter by screwing it onto the valve.
Remove the valve cover on a full, 20-lb. capacity propane cylinder.
Place the empty cylinder underneath the full cylinder, and attach the other end of the propane tank adapter to the full cylinder's valve. Placing the empty cylinder under the full cylinder ensures that you fill the empty cylinder with liquid propane and not gas vapor.
Transfer liquid propane from the full cylinder to the empty cylinder. Wait at least five minutes for the cylinder to fill. Don't overfill the cylinder.
Detach the propane tank adapter from the 20-lb. cylinder, and replace that cylinder's valve cover. Remove the adapter from the recycled cylinder, and replace its valve cover.
Apply sealant to both valves to prevent leaks.
