Safety Tips for Small Propane Bottles


We’ve reported on the need for proper propane installation, including vented lockers and leak detectors (“Some Propane Dos and Don’ts,” PS February 2014), but we’ve not taken a close look at small bottles. All it takes is about two ounces on the average size boat to cause an explosion, so these bottles deserve careful attention.

Propane is about 50 percent heavier than air, so it tends to settle to the lowest reaches of the boat. If the leak is on the countertop and there is some ventilation, most of the gas will mix with ambient air and leave the cabin before it gets chance to settle. If you have bottles larger than 1 pound (typical barbecue bottles are 20 pounds) install a leak detection system with sensors at a low point in the cabin, linked to a fail-safe solenoid located at the tank.

Do not store cylinders—even small bottles—below decks or in lockers that vent below decks. Do not store small bottles in the propane locker; that space is only for the bottles that are installed there and nothing else. If you’re lucky, the boat has a vented locker for portable gasoline tanks. Otherwise, keep the bottles on deck, typically in tubes (see “Pint-sized Propane Locker,” Practical Sailor, June, 2006). Do not store them attached the appliance below decks.

Do not store propane cylinders in your house or garage. The local fire code generally limits you to two 1-pound bottles in the house, attached garage, or detached garage. Larger bottles are not permitted, including the grill parked in the garage in front of your car. It should be outside, either under a cover or in an open-sided shed. Do not store over 120F; on-deck storage containers should be white. Don’t keep cylinders in your car. 

Do not refill disposable propane cylinders. Commercial refilling or transport across state lines carries a $500,000 fine and/five years in prison. If that doesn’t concern you, consider the consequences—burning to death, which sadly has happened.

There are refilling systems, but small bottles do not have an over-fill prevention device, making them vulnerable to over pressurization in the summer heat. You’ll find instructions online, but given that some fail on the first fill, it’s just a really bad idea to try refilling.


We like protecting the threads with brass screw-on storage caps. Or rather, we learned this habit after our field failures. If lightly lubricated, they keep moisture out of the valve area, prevent corrosion of the cylinder threads and valve, and reduce the probability of a valve leak. Will they contain a leak? Probably. Securely tightened, with a good gasket, they will almost certainly slow the leak sufficiently that it will dissipate long before anything bad can happen. Many brands are available at some hardware stores, big box stores, and several online retail sites for about $2 a piece.

Drew Frye
Drew Frye, Practical Sailor’s technical editor, has used his background in chemistry and engineering to help guide Practical Sailor toward some of the most important topics covered during the past 10 years. His in-depth reporting on everything from anchors to safety tethers to fuel additives have netted multiple awards from Boating Writers International. With more than three decades of experience as a refinery engineer and a sailor, he has a knack for discovering money-saving “home-brew” products or “hacks” that make boating affordable for almost anyone. He has conducted dozens of tests for Practical Sailor and published over 200 articles on sailing equipment. His rigorous testing has prompted the improvement and introduction of several marine products that might not exist without his input. His book “Rigging Modern Anchors” has won wide praise for introducing the use of modern materials and novel techniques to solve an array of anchoring challenges. 


  1. Always interested in safety and seeing the small brass caps in the picture piqued my interest. i have one of those caps on the end of a section of stainless steel hose connected to a “Y” junction of our 10 lb propane tank. I use the hose to connect to our BBQ grill. I put the cap on when we’re not using it as I don’t leave it connected to the grill all the time. Prior to that I used the small portable propane bottles for the BBQ. Now I keep 2 on board as backup. I keep them in a seal-able gallon plastic which helps to reduce rust. I have always stored them in the propane locker as I figured it was the safest place to store them. So I’m curious as to why you recommend not storing them within the propane locker which is designed to allow propane leaks to go directly overboard?

    Best Regards,
    Don Romard
    S/V Breezin

  2. and I third the above replies. I am just designing a propane locker and was going to include secure storage for maybe two one-pond bottles as back-up to ensure not running out of propane while out cruising. This seems to be the perfect (and only ) safe place to store these on a boat. tks

  3. The primary concern with storing anything loose in a propane locker is that it can fly around in rough conditions and do damamge. They could rub paint and cause corrosion, break a solenoid wire, or chafe a hose. If you can address these risks, I believe you meet the intent. For example, it is specifically acceptable to have spare large bottles in the locker, if they are secured. The small bottles must be secured, not just dumped in the propane locker. A simple rack (like scuba bottles) or some lengths of PVC pipe could do it. The greatest challenge may be fitting the tank holder in the propane locker, since most are a snug fit already. You should not just squeeze a bottle down the side or lay it across the top.

    In my case the better solution was a vented gasoline tank locker. Much like the propane locker, it is on the bridge deck of a catamaran, is sealed from the cabin, contains no unrelated electrical gear, and vents / drains below. Lacking that, I would have given the propane locker a very close look.

  4. I might add that the danger could be wherever you have the bottles. I have found that the screw-on orifices that also have a button to ignite the gas for soldering, etc, are where I have seen the greatest problem. After reading this article, the idea of a brass cap on the bottle, especially a half-used one, seems like a great way to go. I would no longer rely upon anything but a cap to feel safe, considering that the bottles are in the cellar, where I have of all things a furnace.

  5. Can you substantiate your comment from above: “If the leak is on the countertop and there is some ventilation, most of the gas will mix with ambient air and leave the cabin before it gets chance to settle.”

  6. Re. Countertop location and ventilation. The only code reference point is that ABYC allows butane canisters up to 8 ounces to remain installed in portable stoves when not in use.

    The next paragraph says “do not store cylinders.” The thought, perhaps not clearly articulated, was that propane cylinders would be removed from any appliance, or a torch tip removed, after use. That has always been my practice. Only cylinders in active use, with considerable ventilation, would be in the cabin.

    We’re treading the line between fear mongering and avoiding real hazards. I’ve never had a propane appliance develop a major leak in my presence, and if it did, I would take it outside or screw the bottle off. I have had bottles start to leak after removal on three occasions. Had they been in a cabin locker, they would have vented their contents into the bilge within 4-12 hours, depending on the case, creating a hazard. A storage cap and proper storage can reduce this risk. All of my home propane bottles are capped.

  7. Clarification. ABYC refers to LPG, which includes butane and propane. ABYC develops voluntary, but generally sensible, codes. USCG codes regarding propane are law, but only apply to inspected vessels. However, the USCG regulation states that portable stoves cannot be stored with the propane bottles attached. This is common sense, because in addition to leaks, valves on stoves and torches can be inadvertently opened.

  8. I’ve got a partially used container that won’t screw properly into my grill. Any suggestions on how to remedy this and/or how to safely dispose of the container?

    Ps I use the canvas bags sold by Magma to store my canisters (hung outside on the arch.)

  9. I installed a “momentary ON” switch behind my fire extinguisher, as it was bracketed to the galley wall. This switch was in series with the switch that OPENED and CLOSED the solenoid on the propane tank. If the extinguisher was removed from the mounting bracket, the “momentary” switch was released, opening the circuit, and CLOSING the propane tank solenoid valve. (a momentary ON switch is always “OFF” in the released/extended position, and “ON” while depressed-in this case by the extinguisher body)

  10. How do I on obtain the previous article on large propane tank storage? I have a propane outboard on my 25 ‘ Folkboat sailboat. It now sits in the open cockpit aft secured from movement. You’re response would be deeply appreciate appreciated.

  11. Refillable cylinders were not missed in our research, but a paragraph was cut for length because the kit are out of stock at all of the retailers we had originally listed. We also didn’t feel it was a good idea.

    For $50-80 (not sure if you can find then in stock), Flame King will sell you a DOT certified refillable 1-pound bottle and kit that allows refilling from a larger bottle. Additional bottles are about $10-$12. Obviously, you need to follow the instructions meticulously and do this away from ignition sources and static. You will have fewer empties to dispose of and you will save $3-$4 per refill, but whether it is worth the effort and risk depends on usage. If you are using that many small cylinders, maybe you need a larger cylinder with proper installation.