Propane tank sizes: what size do you need?

Written by Jason Hutchinson
8 Min read
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Whether you’re firing up the grill or heating your house, most of us will use a propane tank at some point in our lives. But when it comes to propane tanks, picking the right size for your needs can be confusing, to say the least!

Getting the right size matters – too small and you’ll be refilling it constantly, too big and you’ll spend a fortune refilling it.

But what is propane, what exactly is it used for and how do you accurately calculate the right size for your needs? Find out all this and more within our handy guide.

What is Propane?

Propane is a gas that is mainly used to heat homes, cook, and refrigerate food. It is also used in outdoor settings to power patio heaters and as BBQ fuel, within industrial settings to make plastic, run machinery, and process heat. Some people use propane to fill their vehicles, known as Autogas or LPG.

Benefits of Propane

Propane fuel is incredibly versatile, clean-burning, non-toxic, and best of all it is portable meaning it has a wide variety of uses across a range of different settings.

Some of the key benefits of Propane include:

  • Efficient – Propane is much more efficient than other heating fuels. It burns hotter and is more concentrated than natural gas, producing twice the amount of energy.
  • Environmentally friendly – Whilst natural gas is considered a greenhouse gas, Propane is not and has even been listed as an approved clean energy source by the 1990 Clean Air Act. Propane doesn’t emit any waste such as sulfur dioxide, nitrogen oxides, or methane, and whilst it does emit carbon dioxide, it is considerably less than other heating sources such as a charcoal grill
  • Portable – Propane cylinders and tanks can be transported, refilled, and installed almost anywhere
  • Longevity – Electrical appliances tend to break or malfunction after regular use, whereas propane appliances tend to be much more robust
  • Reliable – Whether you live in the center of a town or in the depths of the country, Propane is readily available and usually just a short drive or phone call away
  • Cost-effective – Propane heat is cheaper and warmer than electric heat, fact!

About Propane tanks

Propane tanks are the storage vessels for Propane in its liquid form, they are engineered and designed for propane containment at high pressures. Propane tanks are usually installed at a customer’s home and are filled in situ, they differ from propane cylinders or bottles which are essentially portable tanks.

Propane tanks store propane liquid until it’s used either as a liquid or vapor and are only ever filled to around 80% capacity which is classed as ‘full’. Propane tanks are very different from butane tanks because the pressure of propane is much higher.

Are propane tanks safe?

Propane is completely non-toxic, colorless, and virtually odorless liquified petroleum gas, also known as LPG.

When using propane, you should always use your common sense and act safely and with caution as whilst propane as gas isn’t toxic, it is an asphyxiating gas which means it will displace the oxygen in your lungs, making it difficult to breathe if you’re exposed to it in high concentration. Symptoms of propane exposure include:

  • Nausea
  • Dizziness
  • Headaches
  • Coughing
  • Drowsiness
  • Irregular heartbeat

It’s true to say that propane gas is flammable, but in its liquid form, it is not. The National Fire Protection Association (NFPA) has given propane a ‘0’ risk for instability and a ‘4’ for flammability. This means that propane burns readily and as such requires safe handling in use, which means prohibiting smoking or open fires in propane storage areas.

Propane tanks have over 100 years of safety engineering and as such are one of the safest fuels in the world. Designed to be stored for long periods of time, propane tanks are virtually indestructible – you cannot puncture them, and they have been proven to be up to 20 times stronger than tanks that hold gasoline, ethanol, and methanol.

How to avoid exposure to propane

The easiest way to avoid exposing yourself to propane is to familiarise yourself with the smell. Propane gas is completely odorless, but propane companies add a harmless chemical called mercaptan to give it a distinctive scent. This smell has been compared to a rotten egg, a skunk’s spray, or a dead animal, so you’re highly unlikely to miss it!

Types of propane tanks

Above-ground propane tanks come in two different basic types:

1. Horizontal tanks

are sometimes referred to as torpedo tanks due to their unique shape! They have a very large capacity requiring less regular re-filling than vertical tanks and are typically used for households that require propane as the main source of heat in their home. They will most likely be white or green in color

2. Vertical cylinders

are best for more intermittent uses and can be placed right next to a building, allowing them to be hidden out of sight.

How often should propane tanks be changed?

Propane tanks that have a 100-pound capacity or less have an expiry date of 12 years from the date of manufacture. At this point, you can either exchange the tank for a new one or have it inspected for a requalification to allow you to keep it for an additional five years. Larger tanks are regulated and controlled by the supplier.

You can check the expiration date of your propane tank by checking the circular valve guard where you will find the date of manufacture stamped.

How to check the level of propane in your tank

There are several different ways you can check the level of propane in your home tank, regardless of whether you have a 20-pound tank or a large 400-pound tank – the methods are just the same.

Warm water, cool hand method

This is the quickest and easiest way to get a good idea of the amount of propane left in your tank. All you need to do is pour warm water over your tank and then run your hand along the side of it – you will feel a noticeable drop in temperature when you reach the propane level in the tank, which is due to a physical reaction between the hot water on the surface of the tank and the liquid inside.

Obviously, you’re not going to get a precise reading using this method, but it will give you a good idea as to how close you are to needing more fuel.

Using a gauge

Gauges work by reading the pressure inside the tank, showing the volume in terms of how full it is (i.e., 20% full) They can be purchased from most home repair retail outlets and they’re incredibly easy to install and use.

A guide to common propane tank sizes

Before continuing with this guide, it’s worth remembering that propane tanks are referred to by their weight when they’re full. However, knowing what that weight actually means in terms of usage time can be confusing.

This guide to the most common tank sizes aims to help you navigate the world of propane:

20lb tank

  • A typical barbeque tank is referred to as a 20-pounder!
  • Easy to pick up making it portable and convenient
  • Usually exchanged at refill stations when empty for a fresh tank
  • Holds 5 gallons of propane, which will typically last between 18-20 hours if used on a regular-sized grill
  • 18” tall and 12” in diameter

33lb tank

  • Relatively specialized, generally used to power vehicles like forklift trucks
  • Can be used to fuel any vehicle that uses LPG
  • Fairly lightweight, can be picked up and carried by one person
  • Holds 8 gallons of propane
  • 2 feet tall and 1 foot in diameter

40lb tank

  • Most commonly used for large commercial grills or construction heaters
  • Still portable but you may need an extra pair of hands
  • Holds 9.4 gallons of propane and weighs 72lbs when full
  • 29” tall and 12.5” in diameter

100lb tank

  • Mainly used for mixed heating systems or households with minimum propane requirements
  • Useful for cooking, drying clothes, and/or propane fireplaces
  • Placed above ground
  • Holds 23.6 gallons of propane and weighs 170lb when full
  • Will fuel a propane fireplace for around 84 hours
  • 4’ tall and 18” in diameter
  • Can be moved with the help of an extra person

2 x 100lb tanks

  • Two tanks that are secured together with a switchover valve
  • The valve will automatically switch from the empty tank to the full one
  • Green/red indicator to display when a tank is empty

420lb tank

  • Main uses include water heaters, fireplaces, and pool heaters
  • Not the best option for primary home heating
  • Holds 96 gallons of propane when full
  • Can be placed against a building
  • 4.5’ tall and 30” diameter
  • A typical residential property would require two or three cylinders
  • Not portable, refilled on site

500-gallon tank

  • If your home heating is fuelled by propane, this is a great choice
  • Used for residential properties and small commercial units
  • Must be installed at least 10 feet (3 meters) from any building
  • The average US household will need 2 full fills of a 500-gallon propane tank each winter
  • Holds 400 gallons of propane at 80% capacity
  • Not portable, refilled on site

1,000-gallon tank

  • Most often used for large commercial operations or very large homes with a very high-volume requirement
  • Must be installed at least 10 feet from any building and at least 10 feet from any property line
  • Not portable, refilled on site
  • Could be positioned above ground or underground
  • Tanks of this size typically last for around 30 years when properly maintained

Propane tanks quick facts

Here are a few more facts about propane tanks to amaze your family and friends with (they're pretty useful for anyone with a propane tank too!)

  • Cost – The cost to fill a propane tank really depends on the size but it’s worth remembering that propane furnaces operate at 95% efficiency which is over 25% more efficient (and therefore cost-effective) than oil
  • Valves – Propane tanks have three valves: a valve to fill the tank, a service valve that allows propane vapor to fill the tank and enter the gas piping system, and a pressure relief valve to remove excess pressure that might result in overfilling
  • Capacity – When propane changes from liquid to gas it expands more than 200 times its volume. Storing it in liquid form means it can fit in the tank, and the volume of propane that can fit in the tank depends on the tank size
  • Disposal – You can dispose of smaller cylinders by taking them to a refill station or contacting your local municipality. Larger tanks are maintained, refurbished, and reused until they have reached the end of their lifespan
  • Weather – Propane tanks can withstand almost all extreme weather conditions, with a few exceptions such as arctic climates. Tank blankets or vaporizers may help in this situation

Conclusion

Propane is a clean, efficient, safe, and environmentally friendly fuel that has a multitude of uses, from keeping homes and businesses warm to helping power agricultural machinery. Propane is stored in cylinders (smaller volumes) and tanks (larger volumes). Cylinders are portable and can be easily transported with the fuel inside of them, tanks are transported by specialist companies and refilled on site.

There is a range of different sizes of propane tanks available, each with the capacity to hold a different volume of propane – picking the right size according to your needs is easy when you know how!

FAQs

Can propane tanks explode?

Whilst propane is a flammable fuel and can explode, propane LPG tank explosions are extremely rare. Propane tanks operating under normal circumstances are very safe due to the safety mechanisms that are in place to prevent such an accident from happening.
There are two main causes of propane explosions, the first has virtually nothing to do with the tank and is a result of the propane leaking because the tank has been left open and the gas supply is ignited from exposure to flames or high temperatures. On very rare occasions propane tanks explode when the pressure of the tank reaches higher than the tank can safely vent, and usually only occurs when subject to extreme heat such as a fire.

How do I check for a propane leak?

To check for a propane leak you should apply soapy water or a special leak detection solution to where the tanks cylinder valve and regulator outlet connect – bubbles will form if there is a leak

What is the average size propane tank for a house?

The majority of households who use propane as their primary source of heating will need a 500-gallon tank. The average US household will need 2 full fills of a 500-gallon propane tank each winter.

Appliances made simple. 

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