Hey, folks. I refill the small 1 lb coleman cylinders all the time.
Harbor freight sells an adapter you screw onto your warm (60 - 70 F)
20lb cylinder.
Put an EMPTY 1lb into the freezer overnight.
Screw the bottle on the adapter connected to the 20lb.
Flip this assembly upside down THEN open the valve for 1 minute.
Close valve, THEN put assembly right side up.
Remove 1 lb. You will get a poof of gas as the safety tube in the 20lb
purges.
Be sure to remove the adapter for storage to keep the 20lb safe.
This fills them to the perfect level about ten times. Then you can
refill the 20lb.
I believe messing with the valve or filling 2 or 3 times is STUPID!!!
I have done it this way for years.
If the 1lb shows ANY sign of leakage at the valve I simply toss it and
use a new one. Hey, they are pretty cheap and not worth getting killed
over.