Propane Remaining in Tanks

Hi

In an attempt to be able to determine how much propane remains in a tank for resupplying purposes, I did the following:

1.  I weighed the three tanks I purchased and all three were within a few grams of 900g

2.  I do not have any empty tanks, but a google search showed a guy that weighed 24 empty containers (he refills them - long story) and found they averaged 420g

3.  That is a difference of 480g or 16.9oz which is pretty close to the expected 16.4oz of propane in a full tank.

So for my purposes I am going to use the following weights to judge when I have to think about getting a new tank

        Full = 900g

        Half full = 650g

        Empty = 400g

Hope this is useful.