How do you know that it’s full?

On s/v Zero to Cruising, Mike talks about a way to know if your propane vendor has been giving you full measure...

Do you know how to tell if a propane tank is full? As in COMPLETELY full? We didn’t, so of course we did what anyone with internet access would do, we consulted The Oracle to find out the answer. What I learned is that, stamped onto the side of a propane tank, should be the Tare Weight (TW), the weight of the tank unfilled. A 20 lb. tank should then weigh 20 lbs. more than the labeled Tare Weight after it has been topped up.





The Tare Weight of our 20 lb. steel tank is 18 lbs. Why bring this up? Because our tank also has a fancy little gauge on it that, like an automobile fuel gauge, can tell us visually how much propane is in it. When we came to pick up our main propane tank on Wednesday after dropping it off the day prior to have it filled, our gauge did not read full. In fact, it was down what we would consider a fair bit, enough propane to last us quite some time.
Note: We had our propane tank filled shortly before leaving Grenada in November 2011. It only just the other day ran out. You can tell we don’t use all that much propane!





The gauge now reads full, as it should. Anyway, considering that we didn’t really need to get the tank back that day, and they’re charging a fair amount to fill the tanks ($90.00 EC which equates to $33.33 US for a 20 lb. tank), we wanted to have it FILLED. When I complained, the gentleman I spoke to kindly explained that although he didn’t have any way of checking it right there, if we would leave the tank with him, he’d make sure it was looked after.
When we ultimately picked up the tank yesterday we found that our trusty little gauge read full, as it should have. Unfortunately, I think paying for a full tank in these situations but only receiving a portion of what you pay for is pretty common. In fact, I think it happened to us in Grenada too but because of the inconvenience of leaving the tank with them again (we had planned to set sail the next day) we just accepted the fact that we were ripped off a bit. It may not be a lot of money but it is a PITA. Caveat Emptor.

Just for kicks I checked our 10 lb. aluminum tank. It has a Tare Weight of 9.32 lbs. It weighed approximately 15.5 lbs. indicating that it is still about 60% full.

[Ed. Note:  I will also add that there is another set of numbers stamped into the tank that you need to pay attention to - the date of the last hydrostat test that the tank has seen.   In the USA anyway, the tank can be legally refilled for 12 years from that date. Later than that, the tank must be re-hydrostated.]