PROPANE TANK CAPACITY

[ALAN]

A quick question I am sure has been discussed before, but I could not find anything via the search section. I have asked this question numerous times when filling our propane bottles and have never been satisfied with the answers. My understanding is that the 30# propane bottles on our Montana's have a capacity of 7.1 gal of propane (30#/4.23# per gal). They should be filled only to 80% of this number or 5.7 gal. The guage at the places I have gone to always show an empty container when full at 7+/- gal. I do not go to places that charge by the container.

Therefore my question is which amount is correct? 7 gal or 5.7 for a full tank?

For those in the Phoenix, AZ area, Orangewood RV in Sun City, AZ sells their propane for $1.99/gal, same at Ace Hardware in Heber, AZ., if you are near those places.

Alan & Kathy

[David and Jo-Anna]

When my tank is empty, it generally takes 7.3 gallons of propane to "fill" it. If a tank is "full" when it reaches 80% of its theoretical capacity, then I assume the theoretical capacity of the tank is something over 9 gallons of propane.

[Jim Dickey]

A 30# tank is sized to hold 7.1 +/- at 80% of the total bottle capacity.

[Rondo]

That 80% is all they will fill a tank also! They have to allow for expansion of the gas when warmer temps are present. If I'm not mistaken, that 80% fill is regulated by the Feds! Not real sure however! Just what this old brain thinks it remembers!!

[HamRad]

Rondo,
I believe you are correct. It's only been a few years since that particular law went into effect. I guess it is a good one. Although I don't remember there being a major problem with tanks exploding or people getting killed so not sure why the regulation.

By the way I've heard of people putting locks on their propane doors. If you notice all your other doors on the trailer or motorhome will have locks on them. The reason is so that people can get to the propane tanks to shut them off in case of emergency. If you're worried about your tanks getting stolen then you can put a lock on the steel band that holds the tanks in place.

HamRad

[richfaa]

"a typical steel "30 pound" liquid propane tank weighs about 25-28 pounds empty.
propane tank markings (on collar)

propane weighs about 4.125 pounds per gallon and a "30 pound tank" will
hold about 7.5 gallons so a full tank will weigh about 55 pounds or so. "

[noneck]

Right...so way-back-when I used to fill LP tanks we used the stamped markings;

Tare Weight (Tank empty) and WC for Water Capacity (maximum propane capacity is about 80% of WC)

1. Put tank on scale, read TW add #30 and set scale to this number (added a preset about 3 lbs for fill nozzle and hose)

2. Always paid attention to the WC as reference that it would be somewhat higher than my filled amount

3. While filling would use foot to tap the scale to know when I was getting close

[MAMalody]

quote:Originally posted by richfaa

"a typical steel "30 pound" liquid propane tank weighs about 25-28 pounds empty.
propane tank markings (on collar)

propane weighs about 4.125 pounds per gallon and a "30 pound tank" will
hold about 7.5 gallons so a full tank will weigh about 55 pounds or so. "

4.125 X 7.5 = 30.9375

[Art-n-Marge]

Yup, I like MAMalody's math for the propane itself. That sounds about right for 30# tanks.

But in Rich's math he includes the weight of the metal propane bottle and the valve and other hardware. Have you lifted an empty 30# propane bottle? It's pretty heavy and is designed to carry 30# of propane weight plus the bottle. There you go. Probably weighs 55#.

[scductman]

As per mfg of the tanks 24# empty 54# full. I was looking at changing mine to two 40# tanks thats why I looked it up. I would really like to have 40# tanks. JMHO.
bobby

[firetrucker]

Rich, if your "about" is carried to three decimal places, I'd hate to see how many place your "precise" would be.

Bob