Propane Refills

They can only fill to 80 percent.

Many prefilled tanks (Think Blue Rhino) under fills to 15 lbs. And it is disclosed on all the signage.

In your example do they charge one price for a refill? Or do they charge by the weight or by measuring the fill?

a)I have never been to a propane station that charged by weight. It's always been by gallons. They may weigh the tank during fill but still charge by gallon.
b) propane tanks cannot be filled to full capacity, the overflow valve prevents that. IIRC a "full" propane tank is about 80+% of capacity in gallons.
c) places that sell prefilled tanks don't fill to even nominal capacity, and they so state the fill. You do pay a PREMIUM for that convienence!!! Blue Rhino states on the website that since 2008 they only fill to 15lbs. prior to that they filled to 17 lbs.
d) the actual capacity of a 20 and 30 lb tanks is less than 5 and 7.5 gallons of propane if it is filled till the overflow float shuts off fill, about 4.5 ish gallons and 7ish or less gallons.

e) propane only weights about 4.1lbs/gallon,

I only exchange tanks when they are out of date. Otherwise use a metered fill by gallons. The MH tank date is not checked since it's not portable.

CA Traveler wrote:
I only exchange tanks when they are out of date. Otherwise use a metered fill by gallons. The MH tank date is not checked since it's not portable.

yup, IMHO the only good use of tank exchange. I get rid of an out of date tank and get a newer mostly full tank (I check the date on the tank) at a reasonable price and don't have the hassle of recyling the old tank.

A 20 pound tank holds 16 pounds when filled.
The Tare weight (Empty weight) is stamped on the tank.

opnspaces wrote:
They can only fill to 80 percent.

ABSOLTE BULLSH!T !!

It is call a "20 lb tank" because it is design tested and certified to hold 20 lbs of propane ! Some refill stations just crack the overfill screw and fill until liquid vents. This is usually very close to 20 lbs.

All certified portable tanks are require to have a TARE Weight permanently stamped on them. If you weight the tank immediately after filling, that number minus the TARE Weight is how many pounds of propane you received.

opnspaces wrote:
Many prefilled tanks (Think Blue Rhino) under fills to 15 lbs. And it is disclosed on all the signage.

But they have many people CONVINCED this is correct ! BUYER BEWARE !!

matthfam wrote:

There could be a small difference to the 55 lbs supposed weight when full,

You can not know what the "full" weight is without knowing the TARE Weight.

theoldwizard1 wrote:

opnspaces wrote:
They can only fill to 80 percent.

ABSOLTE BULLSH!T !!

It is call a "20 lb tank" because it is design tested and certified to hold 20 lbs of propane !

The 80% rule is mandatory and is regulated by the Department of Transportation (DOT) in the United States and by similar organizations in other countries. Propane retailers and suppliers are required to follow the 80% rule when filling tanks, and customers should expect that their tanks will not be filled to capacity.

To calculate the approximate fill capacity of your propane tank, you can multiply the tank’s total capacity by 0.8 (80%). This will give you the maximum amount of propane that the tank can safely hold, taking into account the 20% head space required for expansion.

For example, if your propane tank has a capacity of 100 gallons, the maximum safe fill capacity would be 80 gallons, which can be calculated as follows: 100 x 0.8 = 80.

From AmeriGas Website

Review the propane tank size guide below for more information on propane tank sizes. It is important to note that a propane tank is only able to be filled to 80%. The tanks details will highlight how many gallons you get when full.

20 lb Propane Tank
Dimensions: 1' 6" in height and 1' in diameter.
Uses: Propane grills, generators, patio heaters, and other outdoor equipment. To purchase or exchange a 20 lb tank, find a location near you.
20 pound propane tanks are often referred to as grill cylinders and hold 4.6 gallons of propane when full.

From another website: 1 gallon of propane weighs 4.11 lb.
Therefore; 4.11*4.6 = 18.9 lbs of propane plus the empty tank weight.

Before I switched to an all electric B, I had four 20lb tanks that I used one at a time in my camper. I kept a chart of the 4 tanks and how much they weighted when full and after each outing and notes on the trip. So I knew were I was for the next trip. Repeat trips that I did every year I knew about how much LP I would probably used. Some trips I used partial tanks others I started full. I tried to get close to empty before refilling and more than one tank before I made a trip for refilling at a location that filled by meter. I stoped using one supplier when my records showed they consistently under filled for what they charged. I like several above only used the prefilled tanks to get better expiration dates. Using the above record keeping, I only ran out on the road once.