[daepp]

I can't speak for the rest of the country - perhaps our another CA law has spread beyond our borders - but our propane tank rules have been changed a couple of times in the last decade. We have been forced to turn in our old tanks and get new ones - first I think for a new universal fitting and then due to some pressure relief valve requirement. Might have been a new max age rule too - not sure.

I have been using them for 30 years without a problem, but now we all have the new ones (for some time in fact).

Then the DIY stores started offering exchange programs where you brought your empty tank in and they sold you a full one. I resisted at first, but I ended up getting the newly compliant tanks for free that way so I didn't complain too much.

My bbq is tied into the house natural gas, but I have two patios heaters and a "fire-table" that use tanks. My heater went out, so I disconnected the tank and as I took it and an extra to the car I noticed that neither were all the light.

Out on the driveway where it was safe I opened the valve on the one I had just disconnected as it seemed heavier - but nothing came out. The more I moved it around the more convinced I was that liquid was still in it.

So I got out the bathroom scale and weighed them.
"Empty" #1 weighed 21.2 lbs.
"Empty" #2 weighed 17.4 lbs.

They look identical - same markings etc - so I remembered that when I used to get them filled the attendant would open a valve with a flat bladed screwdriver. When I opened empty #2 it released some gas.

I re-weighed it, and now it was 16.5 lbs.

So I guess due to temperature etc I am not getting all the propane out with my typical usage.

I have since learned that the tanks all have a "tare" weight on them - so I will be looking for that next time.

But unless you go to a refill station - which are getting rarer with the increase in exchange programs, many many people will be giving propane back to Blue Rhino etc.

I mean, how many people, about to have a party, replace their tanks to make sure they don't run out? I know some may question this, but I think I am of reasonable intelligence (mechanically and otherwise) but I'm now sure I have probably returned tanks that were 15-25% full. So it goes...

Caveat emptor (and let's hoep the RV crowd never starts doing exchanges with their tanks!)