Originally Posted by CADreamin
As predicted, when I checked it tonight, the leak seems to have stopped. We were wondering whether it might have been the sunlight on the tank (it was 80 deg here); however, our neighbor (a fire fighter) said that sunlight wouldn't cause the leak ...
The pressure in a closed propane tank depends only on the temperature of the contents. If the tank warms up significantly when left in the sun, the pressure will rise. It will never get high enough to cause a tank fitting to leak unless the fitting is defective (damaged threads, inadequate thread seal, not tight enough), but it makes sense that it might get high enough to cause noticeable leaking of a fitting with a fault.
On the other extreme, at about forty below, there's no more pressure than surrounding atmoshere... which presents other problems.