Hey, don’t worry, it happens to the best of us. In fact, I know that I have forgotten to refill my propane tanks before camping at least half a dozen times. It’s never fun and I always get frustrated with myself.
But running out of propane isn’t just frustrating, it can also be dangerous. If temperatures are low and you rely on propane as a fuel source for your RVs furnace, running out of propane could turn into a sketchy situation fast.
Luckily, keeping track of propane levels while RVing is quite simple. In this article I’m going to run through the following three methods that can be used to easily check fuel levels:
- Checking by weight
- Using a gauge
- Warm water method
Learn any one of these three methods, and you can rest easy knowing that you have the knowledge and experience necessary to keep your tanks full and gas flowing.
How to tell how much propane is left in your tank
1. Checking by weight
This first method is a tried-and-true technique for assessing how much propane is left in your tank. If you grew up with RVers for parents or have spent a lot of time around someone who loves to grill, there’s a chance you’ve seen some form of this technique in action.
All propane tanks have what is called a “tare weight”. The tare weight of a tank is the weight of the tank when it is completely empty. Most empty propane tanks weigh in the 14-18 lb. range. If you know the tare weight of your RV’s propane tanks and have a scale handy, then you can easily calculate how much propane is in the tank.
While disconnected from the RV, plop the tank down onto your scale and record the weight. Let’s say you do this and your tank weighs 25 pounds. With the knowledge that the tare weight of your tank is 18 pounds, all you have to do is subtract 18 from 25, leaving a remainder of 7.
In this scenario, there are 7 pounds of propane left in your tank. Knowing that a 20 lb. propane tank is only ever filled with 16 lbs. of liquid propane, you can conclude that your propane tank is just under half full.
Digital propane tank scales can be bought for $10-20 online or at a grill supply store. Analog propane scales work just as well and can be found for a bit cheaper.
When this method is performed repeatedly over time, a natural sense of how much a propane tank weighs is developed. Eventually, many RVers are able to check their tank levels just by picking them up and hefting them a few times.
Pros and cons
This method is great because it’s relatively simple and, assuming you already own a bathroom scale, doesn’t require purchasing extra gear for the process. Its primary drawback is that you may have to disconnect your tanks from your RV to lift them onto the scale.
2. Using a gauge
Have you ever heard of a propane tank gauge? Also known as inline pressure gauges, these instruments are similar to fuel gauges on a vehicle and allow an RV owner to check their tank levels with a quick glance.
Installing a propane tank gauge is a very easy process that generally requires no tools. Follow this sequence of steps, and you’ll have your tank gauge installed in no time:
- Fully close the main outlet valve. Do not skip this step!
- Disconnect the propane pressure regulator by unscrewing it counterclockwise. At this point, if you hear a hissing noise or smell propane, stop what you are doing and verify that your main outlet valve is fully closed.
- Thread the new tank gauge clockwise onto the outlet valve of the propane tank.
- Ensure your new gauge is positioned almost vertically, with the display face having a slight tilt that will allow rainwater to easily shed off the side.
- Reconnect the pressure regulator. The propane gauge should now be between the outlet valve and pressure regulator.
- Check that all connections are snug and secure.
- Slowly open the main outlet valve. The needle of the gauge should move and display the level of the propane contained within the tank.
- Verify all connections are sound and whole by testing a propane fueled appliance in your rig.
If you learn best visually, check out this video of YouTuber iScaper1 installing a propane tank gauge on his grill propane tank.
Pros and cons
A propane gauge is incredibly handy to have because it readily tells you the percentage of liquid propane inside your tank. There is no need to disconnect or handle the tank whatsoever.
The main disadvantage of these instruments is that they are sensitive to temperature changes and will read lower in cold winter weather than in the warm summer months. To combat this, just be aware of your current temperatures and take whatever the gauge is reading with a grain of salt.
Warm water method
This last method is certainly the least technical way to tell how much propane is left in your tank.
For this technique, all you need is a small bucket or large bowl and access to hot water. It doesn’t need to be boiling water, but it needs to be hotter than lukewarm. Hot tap water should work just fine.
Fill your bowl or bucket with hot water and carry it over to your propane tanks. Close the tank outlet valve and if you want to keep water off of your hoses and pressure regulator, disconnect them too. Next, pour the water at a medium flow rate on the side of the tank. You want to pour it faster than a trickle, but slow enough that the water has a chance of warming the metal wall of the tank.
Once all of the water is poured, wait 5 seconds, and then use your hand to feel various parts of the tank side wall. Because pressurized liquid propane is extremely cold, it can be deduced that any part of the tank that is cold to the touch is in contact with propane. Any metal that is warmed by the hot water is empty of propane.
So, to recap, you will basically try to heat up the whole exterior of the tank with warm water. A cool spot indicates propane is left in the tank. Warm metal indicates a lack of propane. Use your sense of touch to narrow down how much gas is left. If the whole tank is warm, you are probably dealing with an empty propane tank.
Pros and cons
An obvious advantage of this method is its simplicity. No gadgets or tools are needed, just elements from the Earth and our own sense of touch. As long as you have access to water and heat, this method is doable.
The major drawback to using this method is accuracy. Sure, this method will give you an idea of how much propane is left in your tanks, but it also relies on some guesswork. If you have a large crew camping with you and it’s crucial to have an accurate read on your propane levels, do not count on this method.
Frequently Asked Questions
What is the 80% rule for filling propane tanks?
To allow for expansion due to temperature fluctuations, propane tanks are only ever filled to 80% capacity. A 20 lb. propane tank is filled with 16 lbs. of propane.
How do I refill my RV propane tank?
You can bring your empty propane tank to any number of home improvement stores, supermarkets, or gas stations, and they will gladly fill your tank up for a fee.
Which appliances in my RV use propane?
RVs often use propane to fuel their furnace, refrigerator, water heater, and stovetop.
There you have it! Three simple methods that can be used to keep track of your propane situation. By working one of these methods into your pre-trip routine, you can ensure you never roll up to your campsite with empty tanks.