[h4]A LITTLE ABOUT PROPANE TANKS[/h4]
These "20 lb" tanks are designed to take 20 pounds of propane. They can actually fit another 20% in the tank, but that extra space is designed for expansion as the temperature changes.
All propane tanks have a "tare weight" or "T.W." stamped on the collar of the tank. For a grill sized tank you simply calculate the tare weight + 20 lbs, and that's how much the tank should weigh when it's full. Most 20 lb tanks have a tare weight of +/- 17 pounds when completely empty.
This means a "full" propane tank should weigh about 37 pounds.
There is also a month and year on the collar indicating the date the tank was made. For 20 lb propane tanks, you have 12 years from the manufacture date before the tank must be re-certified with a new date stamped on it. The re-certification only adds 5 years before having to re-certify again. The cost and inconvenience of re-certifying almost always outweighs the price of a new tank.
Brand new propane tanks come with air inside and it needs to be "purged" before the first fill. Purging requires a special adapter to allow a small amount of propane in. The pressure then pushes air out of a one-way bleeder valve. Purging may add another $3-4 dollars to a new tank, though some places don't charge, especially if you buy the tank from them.
[h4]THE MATH ON REFILLS AT COSTCO[/h4]
Internet searches suggest the following:
- 1 gallon of propane weighs 4.2 pounds
- A "full" 20 lb cylinder should have 4.7 gallons or propane in it
I called around and the local U-Haul place wanted $16 for a refill. I remember Costco has a sign for $9.99 refills. I thought I was getting a great deal, but it turns out I pretty much got no deal.
Costco in Greenville, SC is a bit deceiving because they first hand you a slip that says "20 lb cylinder". When you pay inside the receipt says "20lb PROPANE", and the filling print out says "Cylinder: 20S lbs." The only defense is that the filling print out is honest and says "3.6 gallons". However, nobody knows off the top of their head that a propane tank is supposed to have 4.7 gallons to be considered "full". By saying 3.6 gallons, they are masking the fact that they put in 75%. If they wanted to be upfront they'd say "we will put 15 lbs of propane into this 20 lb cylinder".
This means Costco puts in 15 lb of propane.
Code:
3.6 gallons / 4.7 gallons = 75% of the normal fill.
or, said another way
Code:
(4.2 pounds/gallons) * (3.6 gallons) = 15 pounds
The word on the web forums is that the Blue Rhino and AmeriGas similar exchange services put in 75%, or 15 lbs.
If you do the math on Costco, it's actually not a bad price. It's in line, if not cheaper, than paying $16 for a full 20 lbs. Though, Costco's use of the "20 lb" phrase is unfortunate. I think their motivation is to have a cheaper price, so members think they are getting a great deal. Plus, by only filling 75% they make members come back more often, and go inside to shop while they wait.
[h4]CONCLUSION[/h4]
- If you're looking for the best price, owning a propane tank and re-filling it is going to be cheaper than using an exchange service. As always, you pay a premium for convenience.
- Ask how much propane is going into the cylinder. There should be 20 pounds going in for full capacity.
- Weigh the tank when you get home and it should be about 37 pounds. If it weighs 31-32 pounds then you know they only put in 15 lbs of propane.
- Costco's propane price is still fair when you do the math.
- You are welcome to Google it
Happy smoken.
David