Propane Tank Safety FAQ

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It’s clean, it’s portable, and it’s not too expensive. With propane, you can warm yourself up, add some nice ambiance to your outdoor space, and of course, you can power your grill! That said, it may feel daunting to start relying on this fuel—some of us might even be afraid of what could happen if we drop the tank, or hit it with something. Here, we will cover many frequently asked questions about propane: what may cause it to blow up, how far to open the valve, the meaning of some noises you may hear, and much, much more! Read our propane tank safety FAQ below for safety tips and more!

Propane Tank Safety FAQ: What Are the Standard Propane Tank Sizes?

Let’s begin with this one by talking about scale: rather than S-M-L-XL, or grande-venti-trenta, propane tanks are measured by weight, if they are smaller, or gallons, when it comes to the really massive ones. Weight, in this case, refers to when they are full at the top of their capacity.

Propane tanks vary wildly in size: some are as small as 1lb, and some others that are intended for large facilities will fall into the 30,000 gallon category. That said, users like you and me need only concern ourselves with the following sizes:

  • Bottle size: Between 1lb (16oz) and 3lbs. Intended mostly as portable fuel for camping, used on tabletop grills, propane torches, and other appliances of similar size.
  • 20lb: this is the one most appliances (fire pits, heaters, grills) are built for. Easy to carry around, and provides fuel for 8 to 12 hours depending on the appliance that is drawing from it. 33Lb tanks are also available, and are similar to the 20lb ones in portability.
  • Cylinder: 100 to 420lbs. 100Lb tanks can be carried around a bit more easily, which makes exchanging them simpler. 420Lb tanks are usually installed stationary, and come with more restrictions for placement: 5 feet away from windows, 10 feet away from any ignition source, and 10 feet from a property line.
  • Residential: 500 to 1,000 gallons. These are the smallest sizes that come as torpedoes (horizontal rather than vertical), and can be installed underground or above ground. The former’s main advantage is that it saves you space in your yard, but it will require digging and special installation. Tanks that are installed above ground are easier to service, and are built to endure harsh weather conditions—unlike the smaller sizes, but we’ll get on that later.

By now you must be holding onto a few questions: what’s this about weight, if propane is a gas? What do you mean, top capacity? And what is better, exchanging or refilling? All of these will be addressed in due time.

Is It Cheaper To Refill or Exchange a Propane Tank?

Refilling is cheaper, in almost every single way. To begin with, you pay 3 to 4 dollars per gallon when refilling, versus an average of 5 to 6 when refilling. Exchanged tanks guarantee only ¾ of the tank’s capacity, meaning you may often be overpaying on top of the already higher rate. And, it goes without saying, when you refill you take whatever propane was still in the tank back home; when you exchange, any propane leftover is lost.

Cheap is not the same as convenient, of course. Unlike refilling (which requires appropriate facilities and qualified personnel), exchanging can be done at a great many locations, including some that are open after hours and on the weekend, such as gas stations, convenience stores, retail chains like Wal-mart and Home Depot, and so on. You can also rest easy knowing you’re being given a tank that has recently been inspected, cleaned, and tested for leaks.

Tips For Exchanging

It may be more expensive, but there’s no denying how accessible it is. Here are a few suggestions to make your exchange even more smooth.

  • Inspect it. Vendors that exchange tanks must perform their own inspection on their tank stock, but it doesn’t hurt if you give it a once-over. Pay special attention to corrosion or other signs or age, and note the tank’s expiration date; most locations refuse to accept tanks older than 5 years, and if you’re stuck with one of these you might be force to purchase an entirely new replacement.
  • Check the weight. In this case we mean ‘tare weight’, which is how much the tank weighs when empty. A tank intended for 20lbs will be filled with enough propane to reach that weight; thus, a tank with a lower tare weight will allow you to take more propane home.

Tips For Refilling

It’s not as time-consuming as some would have you believe; some locations will even have their staff come to you, fetch your tank, return it and take your payment without you having to leave their car. The main thing, of course, is to find a suitable retailer and keep track of their business hours. Other than that, these points might be of help to you:

  • Mind the expiration date. As mentioned before, most retailers will refuse to deal with tanks that are too old, often past the 5 year mark.
  • Don’t deplete it all the way to zero. If this happens, your refill location might hesitate to service you, as there is no way for them to know if the tank was emptied in service, or if it has a leak, without a full inspection. A tank that holds a little propane is a tank that is working properly.

Are Propane Tanks Lighter When Empty?

Indeed they are. As we have discussed before, all tanks have (and display) a ‘tare weight’. This is how much the tank weighs when it is empty, and is a good point of reference to find out how much propane you have left; but we will cover that in depth further down.

Can You Refill a Propane Tank Before It’s Empty?

You can; it is, in fact, more advisable than refilling when the propane within is completely exhausted. Aside from saving you some headaches due to your tank being suspected of a leak, it also means you do not run out of fuel for grilling, warming up, or the specific use you give to your propane supply.

Bonus pro tip: when it comes to tanks between 20 and 100lbs, it is generally advised to keep two tanks. That way, when one runs out you can switch to the spare one and keep your activities going while you get the counterpart refilled or exchanged. 100Lb tanks specifically are often set up in pairs, with a change-over regulator and indicator system in between. When the indicator switches from green to red, it means the first tank has run out and you are now drawing from the second; and thus, it is time to exchange.

Are Propane Tank Gauges Accurate?

Reliable? Yes. Accurate (compared to, say, a digital thermometer)? No, not very. One factor is diameter: the smaller the gauge is, the more its accuracy suffers. The gauge most tanks come with is a float gauge. It doesn’t go by pressure or volume, only level. All it does is provide an approximate percentage of how full the tank is, and it is intended to give the consumer (you) merely an estimate on how much propane remains within.

Operators don’t even look at this gauge when filling your tank; rather, they rely on the bleeder valve. When liquid comes out of it, it’s a sure sign that the tank is as full as it can get.

How Do I Know How Much Propane I Have Left?

The tank gauge may be reliable, but there are times when we just don’t trust it, or it stops working (it is, after all, comprised of several moving parts). Here are other ways to find out how much propane is still in your tank.

Tare Weight

Weigh the tank, and subtract the tare weight it has written on it. The difference is how many pounds of propane are within the tank.

Water Test

Pour warm water on the side of the tank. Place your hand at the top, and slowly feel further and further down along the area where the water ran. Stop when you feel a cold spot: that’s the propane level.

How Much Pressure Can You Put in a Propane Tank?

The optimal range for propane tanks is 100 to 200 psi. If pressure goes higher than that, the vent will activate, releasing pressure until it is back to optimal levels. If pressure is too low, the best way to remedy that is by refilling the tank.

There is no need to worry if pressure fluctuates, as long as it is within that range. In hotter days, pressure within the tank will rise, and it will descend during colder days. This is perfectly normal.

Why Does My Propane Tank Feel Like Liquid Is Inside?

For the same reason tanks can be scaled by weight (unlike, say, helium balloons), and use float gauges to measure their reserve: what lies within your tank (before you open the valve) is, in fact, a liquid, stored at high pressure to prevent it from vaporizing—which, for propane, happens at a temperature of -44°F. When you open the valve, the pressure is released, which allows the propane to evaporate, flow out of the tank and through the burner for combustion. This is also why tanks are never filled past 80% of their capacity (which is the level at which bleeder valves start to ooze liquid): that remaining 20% is the space necessary for vaporization to happen.

Should You Open a Propane Tank Valve All the Way?

With something so volatile as propane, it’s no wonder we want to play it safely; common sense might tell us, let’s open the valve only as necessary, and that means the stream is more manageable—we can even shut the valve in two swings if there’s an emergency. The reality, however, is different.

Propane tank valves are built in such a way that they are sealed only in two positions: fully closed, and fully open. For this reason, whenever you are going to use your tank, it is better to open the valve all the way; not doing so risks a leak at valve level, and it is also possible that the gas coming through the burner is so little the flame goes out, but the propane is still coming out even though it is not burning. Nobody wants that. Rather than at tank level, you can usually control how much gas actually comes out from your appliance, be it a fire pit, a grill or a heater, as most of them come with a knob to regulate intensity.

Something to remember, though: when you open the valve, don’t do it too fast. We’ll explain why later.

Should Your Propane Valve Be Clicking?

There are a few types of noise your valve might make while it is open. Clicking is one of them. Is it bad? If it is quieter and rather steady, no; it is a sign that your valve is working properly. If, on the other hand, it is a louder, more frantic clicking, then it is best to close the valve and have the tank checked.

Why Is My Propane Tank Hissing?

If the valve is closed, then it might just be the tank releasing excess pressure; this can happen when the day is hotter, raising the pressure within, which prompts the vent to release the excess. Another reason could be, if you but recently got a delivery or refill, that the bleeder valve was not properly closed by your operator. You can test this by turning the bleeder valve clockwise until you can’t turn it anymore. See if that stops the hissing.

Hissing can also be a sign of a leak. For more on how to deal with this, read on to our next section.

How To Stop a Propane Tank From Leaking

First things first: close the valve. Then, as long as the smell of rotten egg (which is added to the normally odorless propane to tell of a leak) is not too strong, proceed with the following steps.

  1. If your tank is connected to some appliance, unplug the hose; check it for any holes, and reconnect it securely. See if that fixes it.
  2. If your tank is not connected to anything, or the hissing persists while the valve is closed, then prepare a solution of one part liquid dish soap and one part water, and pour it into a spray bottle. Apply liberally all over the tank’s gauge and valve, and look for bubbles. That will tell you where the leak is.
  3. Try tightening the valve, and the screws of the face gauge; the former will require turning clockwise, whereas the latter will involve the use of a Philips screwdriver. If you don’t smell gas, then wait 10 minutes, and spray the gauge and valve again with your soapy solution. No bubbles? Good, then it is fixed. Otherwise, you need to call your propane tech.

If You Keep Smelling Gas and Can’t Find the Leak

In summary: it’s time to hightail it.

  1. Close the valve all the way, put out any flames, and turn off anything that could throw a spark, such as electronics, appliances, or light switches. This includes your cellphone.
  2. Evacuate the area, opening as many windows as you reasonably can on your way out; this will help reduce the accumulation of gas within the house.
  3. Do not stop to collect anything! Breathing gas may eventually slow you down, and prevent you from leaving.
  4. Once you are at a safe distance and without risk of igniting the gas, call your propane supplier, or 911.

If You’d Rather Not Rely on Your Nose

Anosmia, getting on in years… many are the circumstances that might prevent us from smelling gas if it starts leaking. Good news: you have options. Place a detector on the nearest wall, closer to the ground (if you want it for detecting natural gas you’d set it higher up), let it warm up, and rely on it to sound the alarm if propane concentrations begin to rise beyond a safe limit. Some detectors are specifically designed to help you sniff leaks out, should you ever have the need.

Will a Propane Tank Work on Its Side?

It technically will, but not for long, and you really shouldn’t do that. To recap: propane is stored in your tank in liquid form, under high pressure to prevent it from evaporating. When you open the valve, pressure is released, vaporization occurs, and you get the gas flowing through the line and out of the burner. Tanks are full at only 80% of their capacity; the remaining 20% at the top is what enables the reaction to happen. When you tilt the tank, you’re bringing the liquid into the valve, and that’s what will be running through the line—which can cause your flame to quickly grow too big too fast.

The risk we have spoken about should be more than enough to prevent any sane person from trying to use their tank sideways. Whoever chooses to take their chances, however, should know that they might also be causing damage to the inner workings of the tank, the overfill protection device (OPD) specifically, which is what indicates when the tank is full at 80%. If this part is rendered inoperable, fully replacing the tank might be in order.

That said, all is not lost for those who really, really want to place their tanks horizontally. All that is needed is the right tank. Wheels, anyone?

Can a Propane Tank Be Used Indoors?

Anything bigger than a camping cylinder should stay outside, and it’s mainly got to do with the vent. As we have said before, this vent releases pressure, i.e. gas, when it rises past a certain limit—which can easily happen during a particularly hot day. Nobody wants that to occur inside the house. 5Gal tanks (like the 20lbs ones) and up are actually forbidden by relevant regulations across the country.

Camping cylinders, on the other hand, are okay; and they can usually provide enough fuel for just about anything you need done around the house.

Why Is There Frost on My Propane Tank?

You may remember from a few sections back, how pressure rises when the tank is exposed to higher temperature, and dips under lower temperatures. This relationship works in reverse too: when the pressure drops (namely, when you open the tank’s valve), so does the temperature on the tank’s walls. If pressure goes down fast enough, the temperature will follow with similar speed, to the point that you could see frost on the tank even on a warm day. This can be observed on a great many high-pressure containers, more famously with pressurized air cans.

Is it dangerous? No, but it is something to be mindful of, as we will explain just a bit further down.

Can a Propane Tank Stay Outside in the Winter?

It’s better that it doesn’t. Certain levels of cold can affect your tank in quite a few ways which, while not exactly hazardous, may prevent you from drawing on your propane supply when you need it the most. More about that in the next sections.

Will a Propane Tank Freeze?

In the literal sense of the word, no. Propane freezes at -306°F, and the lowest temperature ever recorded on this planet is -128°F. If you ever wanted to see your propane turned into a block of ice, you’d have to take your tank all the way to Neptune. However, your tank can still be affected if your winter is harsh enough.

Potential Effects of Cold Weather

Here are the effects you may encounter—possibly when you need your tank the most, it turns out.

Propane Won’t Come Out

Propane turns to vapor at -44°F. If the temperature is lower than that, then it will stay liquid, even if you open the valve.

Frozen Components

Handle, valve and regulator may be affected by ice forming upon them, even if the temperature is not as low. It could be as simple as snow coming to rest on them, melting just halfway and then turning to ice when temperatures drop at night; it can also be condensation settling in and freezing later on, getting the valve stuck or obstructing the valve.

Preserving Your Tank From the Worst of Winter

The aforementioned effects are not inevitable. Here’s how to help your tank keep working for you when days get colder.

Don’t Open the Valve Too Quickly

We noted it when we were talking about opening the valve all the way. If pressure drops too fast, temperature will too. If your ambient temperature is low enough, this sudden drop may render the tank too cold for propane to vaporize.

Layer It Up

Keeping it warm seems like a sensible enough solution, but it has to be done right. Given how flammable propane is, you can’t use any old heat source on the tank. Fortunately, there are blankets specifically designed to fill this role. They’ll keep your tank warm while it works, without the risks other solutions would entail.

Top It Up

Cold ambient temperature will result in lower pressure, which will bring the tank’s temperature further down, potentially to the point of keeping the propane liquid. A full tank will help keep pressure steady during the cold season, helping prevent this issue. But don’t overfill it, either: if there is not enough space, then pressure drop might be insufficient, leading to your propane staying a fluid.

Bring ‘Em Closer

If you have multiple propane tanks, store them in close proximity to one another. This will make them all a bit more resistant to freezing.

Mind the Components

Vent, valve, regulator, are the parts that can freeze up if exposed to snow or condensation. Face the vent down, to prevent ice from accumulating on it, and ensure the tank’s blanket is on valve and regulator if you’re using one. Otherwise, you can also use an old rag or a milk carton to protect them, always making sure the vent is not obstructed.

Use Propane With the Right Additives

Some propane fuels come with methyl alcohol mixed in; this makes them less likely to be affected by cold temperatures.

Can Propane Tank Lines Freeze?

Going back to what we just discussed—literally, no; but technically, yes. Propane itself won’t turn to ice anywhere on this planet, but the lines and the regulator can still freeze up. Here’s what you can do to help prevent it (in addition to the measures we listed above):

  • Don’t overfill the tank. Aside from potentially making the pressure within insufficient for the propane to vaporize, an overfull tank can feed liquid propane to the regulator, which will cool it off so fast it could freeze it. If your tank does not have an overfill protection device, see about getting one that does.
  • Keep it upright. Your tank may be full at only 80 or even 40%, but that won’t do you any good if you tilt it and end up bringing liquid (and very cold) propane to the regulator.

Can You Put Heat Trace on a Propane Tank?

For those unfamiliar: heat trace is a set of paths made of a resistive element, which are typically laid out along pipes and around vessels (such as tanks, yes, but let’s put a pin in that). An electric current is sent through these paths, making them get hotter, which in turn warms up that which they are laid upon. Heat trace comes in two versions: one more rigid that can be bought in bulk, and which is used mostly by professionals; and a more flexible one, like a rope or tape, which is more DIYer-friendly.

To answer the question: it is better to avoid any sort of heat trace on a propane tank. For starters, it’s not really necessary—heat trace, after all, is intended for preventing certain fluids from freezing up while flowing through their pipes (water, for example), or for working against condensation. Propane will never actually freeze, and preventing everything else from icing up is not that hard—as we’ve discussed previously.

Heat trace is also not worth the risk: it’s not exactly impossible for heat trace to run too hot, making the tank itself overheat… with highly undesirable results we will talk about further down.

Can a Propane Tank Get Wet?

Tanks that are permanently installed outside and above ground (500gal and up) are designed to endure any sort of weather without suffering decay. This is not so with portable tanks, like the commonly used 20lb. If one of these tanks is exposed to moisture, it could develop rust, and even pitting, which is a particularly aggressive (but fortunately rare) form of corrosion that can weaken metal to the point of rendering it unusable. If this were to happen to your tank, you would have no recourse but to throw it out and get a replacement.

If at all possible, avoid rain when using your tank. And never place it on wet ground, be it for storage or for using.

Can a Propane Tank Be in the Sun?

Keeping your tank out of the sun is highly recommended. Otherwise, the tank might heat up enough to release pressure, which will result in an entirely preventable loss of gas. But it doesn’t end there: if the temperature gets too high, it could turn the tank into a safety hazard, which we will discuss in detail a bit later.

Can a Propane Tank Be Stored in a Garage?

No; a tank should not go into the garage, or anywhere inside the house, for storage or for using. It is indeed recommended to store the tank in a secluded location, but the place has to be chosen carefully. We shall elaborate fortwith.

How Should I Store My Propane Tank?

It should be in the shade, where no sunlight, rain or snow can get to it. It should be at a certain distance from the home, and there should be plenty of ventilation. This rules out (aside from the house itself, of course) the garage, the basement, the porch, and the shed.  Always keep it upright, with the valve closed all the way; and if it’s winter, remember to follow the recommendations we set out a few sections back.

Will a Propane Tank Blow Up in a Car?

If you’re asking whether it’s safe to travel with a propane tank in the car, then the answer is yes. Unlike liquid nitroglycerin, propane won’t explode if your car hits a pothole or a speed bump. However! You should not leave your tank in your closed car for prolonged periods. In certain seasons, a car can get hot enough to bake turkey, and your tank must never be in that sort of environment.

When transporting your tank, be sure to keep it upright, with the valve tightly closed; and secure it as best you can, so it won’t topple over (which, as we know, can be bad for the tank). An appropriate base for transit (and, why not, for use and storage) will do wonders.

Will a Propane Tank Explode if Dropped?

So, we’ve established it’s okay to hit a pothole or a speed bump while traveling with a propane tank. Dropping it, though, is an entirely different matter: the thought of the tank falling 2 or 3 feet before clashing against the ground must be dreadful for a great many people. The reality is different, however, as propane tanks are far more hardy than one might think. Some tanks, in fact, have ended up with a dent due to particularly potent impacts, and they remain in service, even if they may not look as sleek as before.

Will a Propane Tank Explode if Shot?

Okay, fine, the tank won’t explode if my fingers are slippery. But what about a bullet? Surely, that must be quite enough to make a tank blow up, right? Right?

Surprising as it may be, a propane tank is in fact sturdy enough to take a bullet without rupturing. That said, we don’t see why anyone would want to put it to the test.

Will a Propane Tank Explode in a Fire?

This is a tricky one. Will the tank itself blow up to pieces? Unlikely. Will it cause an explosion? That could happen far more easily. Let’s elaborate.

Propane Tank Safety FAQ:BLEVE

This acronym means Boiling Liquid Expanding Vapor Explosion, and it is a phenomenon which, though rare, is directly associated with substances stored as liquids at high pressure, such as propane. This high pressure essentially raises the fuel’s boiling point, which is how it stays a liquid. When you open the valve, the pressure drops, the boiling point does as well, and thus propane turns into vapor and you get to use it in its gas form.

When temperature rises, pressure increases, due to the gas within the tank expanding. Eventually, the tank’s vent kicks in, releasing gas until pressure returns to manageable levels. If, however, the rise in temperature is fast and unbearable, then the gas may expand faster than the vent can release it, which can lead to the tank rupturing. When this happens, then the pressure is nonexistent in an eye’s blink; the boiling point plummets so fast, propane boils and vaporizes spontaneously, and so violently it causes a blast, similar to how a balloon audibly pops when you puncture it and pressure within is suddenly zero. Given how it works and its potential for damage—especially for flammables, which may be more destructive should they come into contact with a source of ignition—, this is, indeed, considered an explosion, and some larger BLEVE incidents have been particularly devastating.

BLEVE incidents are, fortunately, rather rare, as they require a rather dramatic and steady rise in temperature. There have been some cases in which a fire erupts all around the tank and nothing happens (though the tank itself is usually retired afterwards). That said, it’s better not to risk it; and this is why it is so insistently recommended to preserve the tank from higher temperatures: no undue sun exposure, no leaving it in the car unattended, and no heat trace or anything of the sort. At best, you will waste gas; if it happens in a closed space, the gas will concentrate, with predictable consequences. And, at worst, an actual explosion could happen.

In Closing: Propane Tank Safety FAQ

Propane is a fuel with quite a few benefits: it’s low on emissions, it’s portable, and it can be used for just about anything, depending on the size of your tank—cooking, heating, ambiance, even drying. It’s not as volatile as one could think, and nothing will happen if you happen to drop it or bump into it. That said, treating it appropriately goes a long way: preserve it from the worst of winter, keep it in cool, shaded, well ventilated areas… and if you smell rotten eggs, act quickly and decisively.

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