RV Propane Tank Types
The most common type of RV propane tank is the vertical or upright steel cylinder propane tank with a metal collar protecting the valve as well as a circular metal footing to stabilize the propane tank and allow the tank to stand upright.
Propane tanks also are either DOT (Department of Transportation) or ASME (American Society of Mechanical Engineers) tanks. DOT propane tanks are usually the upright or vertical tanks that sit on the front of the Airstream or other camper trailers while the ASME propane tanks are usually horizontal tanks that are built inside non-Airstream RV motorhomes. The DOT propane tanks are easily removable and portable, so you can simply take the DOT propane tank off the Airstream and bring it to a propane supplier to be refilled. ASME propane tanks are permanently fixed inside the RV, so you need to bring the entire RV to the propane dealer to get your ASME tank refilled.
RV Propane Tank Sizes
The most common size for an Airstream trailer propane tank is the vertical DOT 30 lb propane tank. Most 20 foot and longer Airstreams come with two 30-lb propane tanks mounted in the front of the trailer on the A-frame tow bar. The smaller Airstream Basecamp and Airstream Nest trailers use 20 lb propane tanks while the larger Globetrotter and Classic Airstreams come with two 40 lb propane tanks.
Determining your Airstream’s propane use
Determining how much propane you’ll burn thru really depends on tracking how often and how long you use the propane furnace, the propane oven and stove as well as the propane water heater. Also if you’re not hooked up to shore power electrical, your RV fridge will be running on propane as well.
The RV propane furnace will usually use the most propane in colder weather because of its more constant use. Knowing what size RV furnace you have as well as how much heat it puts out will help you estimate your propane requirements. Heating output for furnaces is measured in British Thermal Units or BTUs and is the amount of propane (or other energy) it takes to heat a pound of water one degree Fahrenheit.
As far as heating your Airstream, most RV furnace experts recommend installing a furnace that can output at around 700 to 1000 BTUs for each foot-length of your Airstream. For my 23 foot Flying Cloud, I should have a propane furnace that puts out at least 16,100 BTUs (700 x 23 ft). Airstream specs out the 23-foot trailers with an 18,000 BTU ducted furnace and so far this winter, I’m been toasty warm at night with lows down to 28-30 degrees.
To figure out propane use – a gallon of propane can produce roughly 100,000 BTUs per hour, so my 18,000 BTU furnace will use just under 0.2 gallons an hour if it’s heating continuously. A 30-lb propane tank holds about 7 gallons of propane when filled, so you could run your furnace non-stop for about 35 hours on a full 30-lb propane tank. Obviously, except in extremely cold conditions or if the windows or roof vents were left open, would the furnace have to run continuously.
How to calculate how long your RV propane tank will last
I’ll warn you ahead of time, running out of propane in the middle of a cold winter night is not the best idea if you want to stay cozy in your Airstream. I’ve learned through (ahem) “experience” that having a good idea of how much propane you’re using especially while boondocking in the middle of nowhere makes planning those propane runs back into town a lot easier to plan.
How much propane does a propane tank hold?
While propane tanks are listed by weight (i.e. 20 lb, 30 lb, etc), you’ll notice that propane suppliers typically charge by the gallon of propane. So it’s important to know how many gallons of propane your tank can hold. At normal temperatures, a gallon of propane weighs approximately 4.2 pounds (or 1.9 kilograms) so a 20 lb propane tank should hold about 4.75 gallons of propane. A 30 lb propane tank should hold about 7.1 gallons of propane and a 40-pound tank will hold about 9.5 gallons of propane.
How much propane is in a full propane tank?
If you’re new to the Airstream or RV life, you might be surprised to find out the propane tanks are only filled to about 80% of their capacity. The reason for not completely filling the propane tanks is to account for changes in temperature and the resulting expansion of the propane. When the temperature rises, the propane gas will expand, increasing the pressure inside of the tank. When the temperature drops, the pressure inside the tank with also drop.
How to tell when your propane tank is empty
You don’t want to be surprised at 3 am in the morning when its 36 degrees outside and your propane furnace runs out of propane. So it’s important to know how to tell when your propane tank is near empty and should be refilled before going out on a long camping trip.
DOT propane tanks should have their empty tank weight (also known as “tare weight” stamped on the collar of the tank). If you know what the empty weight of the propane tank is, then it’s simply a matter of weighing your tank and subtracting the tare weight and that will give you an approximation of how much propane is left in the tank.
How much does an empty propane tank weigh?
- An empty 20 lbs propane tank weighs about 17 pounds
- An empty 30 lbs propane tank weighs about24 to 25 pounds
- An empty 40 lbs propane tank weighs about 31 to 32 pounds
- An empty 100 lbs propane tank weighs about 66 to 68 pounds.
How much does a full propane tank weight?
You can calculate the full weight of a propane tank by adding the listed weight of the propane tank to the empty (tare weight) of the tank.
A full 20 lbs propane tank weighs about 37 pounds (20 lbs propane + 17 pounds for the weight of the tank)
A full 30 lbs propane tank weighs about 54 to 55 pounds
A full 40 lbs propane tank weighs about 71 to 72 pounds
A full 100 lb propane tank weighs about 166 to 168 pounds.
Using a propane fuel gauge
I haven’t installed a propane fuel gauge yet, but there are a number of these gauges on the market that attach directly to the propane tank. The less expensive propane fuel gauges simply give a visual gauge with a needle to show how much propane is left. Some of the newer propane fuel gauges also work with a cell phone app so you can check your propane fuel levels while you’re inside your camper.
How to weigh your propane tank
I use a digital luggage scale I purchased at Amazon to weigh my propane tanks. The digital luggage scale works well up to the 30 and 40 lb propane tanks. For the 100-pound propane tanks, you’re better off using a regular bathroom scale.
Propane tank recertification guide
Refilling vs exchanging your propane tank
One common question many new Airstream owners have if its better to refill or exchange your propane tank when empty. The answer really depends on a few factors.
Cost of propane tank refill
If you do your homework, you’ll find a wide range of prices for propane refills. Campgrounds typically charge much more than a local propane supplier. The RV park where I’m at now charges over $4 a gallon of propane while the local supplier that I typical use comes in right around $2.00 a gallon depending on the time of year.
Left-over propane in the exchanged tank
If you’re exchanging or trading-in your propane tank, remember that there is often some propane left in the tank that you are exchanging. So if you echange the tank, you’re essentially giving away that remianing propane that you had already paid for. So this is one reason why refilling your propane tank is typically a better deal.
Exchanged tanks are not always completely filled
Those 20 lb propane tanks that you get through your local hardware or big box store area typically only filled with about 15 lbs of propane. So you’re often only getting about 3.5 gallons of propane (15 lb divided by 4.2 gallons) compared to the expected 4.75 gallons of propane in a 20 lb propane tank.
When to buy a new RV propane tank for your Airstream
Since Airstreams typically come with two RV propane tanks (except for the smaller Basecamp and Nest Airstreams) you might not ever need to to buy a new propane tank. But, its important to know when you should think about replacing the old propane tank(s) and buying a new tank.
1. Physical damage to the existing propane tank
Accidents do happen and if you notice any visual dents or other physical damage to the propane tank. The DOT-approved propane tanks are made out of steel and pretty resistance to puncture and damage. But the tanks can be dented or punctured if you back your tow vehicle into them or are in an accident. If you drop a propane tank from high enough onto a hard surface, that force can also dent the tank.
If you do notice any damage to one of your propane tanks, you should immediately get the tank inspected by a qualified propane supplier that also recertifies propane tanks.
2. Rust or other signs of aging to the tank
Most propane tanks are made from steel and can rust. There are some tanks that are made from aluminum which don’t rust, but these propane tanks are also a lot more expensive than the steel propane tanks. Rust may indicate weakening of the steel as well. if there’s a small area of rust, disconnect and remove the tank from your Airstream and try removing the small rust spot with a steel wool pad or a small wire brush and then repaint the area to prevent the tank from rusting again. If there’s more extensive rusting or if there’s rust around the valve, then get the tank inspected before continuing to use.
3. If the propane tank fails its recertification test
Propane tanks need to be re-certified after 12 years in the United States and after 10 years in Canada. If your tank fails a recertification inspection then its time for a new tank.
Read about propane tank recertification here