Introduction:

What is propane?

Propane is a three-carbon alkane with the molecular formula C
3H
8,Propane is a colorless gas with a faint petroleum-like odor. It is shipped as a liquefied gas under its vapor pressure. For transportation it may be stenched. Contact with the unconfined liquid can cause frostbite by evaporative cooling. Easily ignited. The vapors are heavier than air and a flame can flash back to the source of leak very easily. The leak may be either a liquid or vapor leak. The vapors can asphyxiate by the displacement of air. Under prolonged exposure to fire or heat the containers may rupture violently and rocket.

History of propane

Propane was first identified as a volatile component in gasoline by Walter O. Snelling of the U.S. Bureau of Mines in 1910. The volatility of these lighter hydrocarbons caused them to be known as "wild" because of the high vapor pressures of unrefined gasoline. On March 31, the New York Times reported on Snelling's work with liquefied gas and that "a steel bottle will carry enough gas to light an ordinary home for three weeks."

It was during this time that Snelling, in cooperation with Frank P. Peterson, Chester Kerr, and Arthur Kerr, created ways to liquefy the LP gases during the refining of natural gasoline. Together, they established American Gasol Co., the first commercial marketer of propane. Snelling had produced relatively pure propane by 1911, and on March 25, 1913, his method of processing and producing LP gases was issued patent #1,056,845. A separate method of producing LP gas through compression was created by Frank Peterson and its patent granted on July 2, 1912.

The 1920s saw increased production of LP gas, with the first year of recorded production totaling 223,000 US gallons (840 m³) in 1922. In 1927, annual marketed LP gas production reached 1 million US gallons (3,800 m³), and by 1935, the annual sales of LP gas had reached 56 million US gallons (210,000 m³). Major industry developments in the 1930s included the introduction of railroad tank car transport, gas odorization, and the construction of local bottle-filling plants. The year 1945 marked the first year that annual LP gas sales reached a billion gallons. By 1947, 62% of all U.S. homes had been equipped with either natural gas or propane for cooking.

In 1950, 1,000 propane-fueled buses were ordered by the Chicago Transit Authority, and by 1958, sales in the U.S. had reached 7 billion US gallons (26,000,000 m³) annually. In 2004 it was reported to be a growing $8-billion to $10-billion industry with over 15 billion US gallons (57,000,000 m³) of propane being used annually in the U.S.

The "prop-" root found in "propane" and names of other compounds with three-carbon chains was derived from "propionic acid".

What are the uses of propane?

Propane is a popular choice for barbecues and portable stoves because the low boiling point of −42 °C (−44 °F) makes it vaporize as soon as it is released from its pressurized container. Therefore, no carburetor or other vaporizing device is required; a simple metering nozzle suffices. Propane powers some locomotives, buses, forklifts, taxis and ice resurfacing machines and is used for heat and cooking in recreational vehicles andcampers. Since it can be transported easily, it is a popular fuel for home heat and backup electrical generation in sparsely populated areas that do not have natural gas pipelines.

A 20 lb (9.1 kg) steel propane cylinder. This cylinder is fitted with an overfill prevention device (OPD) valve, as evidenced by the trilobular handwheel.

Propane is generally stored and transported in steel cylinders as a liquid with a vapor space above the liquid. The vapor pressure in the cylinder is a function of temperature. When gaseous propane is drawn at a high rate, the latent heat of vaporisation required to create the gas will cause the bottle to cool. (This is why water often condenses on the sides of the bottle and then freezes). In addition, the lightweight, high-octane compounds vaporize before the heavier, low-octane ones. Thus, the ignition properties change as the cylinder empties. For these reasons, the liquid is often withdrawn using a dip tube. Propane is used as fuel in furnaces for heat, in cooking, as an energy source for water heaters, laundry dryers, barbecues, portable stoves, and motor vehicles.

Commercially available "propane" fuel, or LPG, is not pure. Typically in the United States and Canada, it is primarily propane (at least 90%), with the rest mostly ethane, propylene, butane, and odorants including ethyl mercaptan. This is the HD-5 standard, (Heavy Duty-5% maximum allowable propylene content, and no more than 5% butanes and ethane) defined by the American Society for Testing and Materials by its Standard 1835 for internal combustion engines. Not all products labeled "LPG" conform to this standard however. In Mexico, for example, gas labeled "LPG" may consist of 60% propane and 40% butane. "The exact proportion of this combination varies by country, depending on international prices, on the availability of components and, especially, on the climatic conditions that favor LPG with higher butane content in warmer regions and propane in cold areas".

Domestic and industrial fuel

Propane use is growing rapidly in non-industrialized areas of the world. Propane has replaced many older other traditional fuel sources. The "propane" sold outside North America is actually a mixture of propane and butane. The warmer the country, the higher the butane content, commonly 50/50 and sometimes reaching 75% butane. Usage is calibrated to the different-sized nozzles found in non-U.S. grills.^{[citation needed]} Americans who take their grills overseas — such as military personnel — can find U.S.-specification propane at AAFES military post exchanges.

North American industries using propane include glass makers, brick kilns, poultry farms and other industries that need portable heat.

In rural areas of North America, as well as northern Australia and some parts of southern India propane is used to heat livestock facilities, in grain dryers, and other heat-producing appliances. When used for heating or grain drying it is usually stored in a large, permanently placed cylinder which is recharged by a propane-delivery truck. As of 2007, 9.7 million American households use propane as their primary heating fuel.^[19]

In North America, local delivery trucks with an average cylinder size of 3,000 US gallons (11,000 L), fill up large cylinders that are permanently installed on the property, or other service trucks exchange empty cylinders of propane with filled cylinders. Large tractor-trailer trucks, with an average cylinder size of 10,000 US gallons (38,000 L), transport the propane from the pipeline or refinery to the local bulk plant. The bobtail and transport are not unique to the North American market, though the practice is not as common elsewhere, and the vehicles are generally called tankers. In many countries, propane is delivered to consumers via small or medium-sized individual cylinders, while empty cylinders are removed for refilling at a central location.

Propene (also called proplylene) can be a contaminant of commercial propane. Propane containing too much propene is not suited for most vehicle fuels. HD-5 is a specification that establishes a maximum concentration of 5% propene in propane. Propane and other LP gas specifications are established in ASTM D-1835.^[20] All propane fuels include an odorant, almost always ethanethiol, so that people can easily smell the gas in case of a leak. Propane as HD-5 was originally intended for use as vehicle fuel. HD-5 is currently being used in all propane applications.

Refrigeration

Propane is also instrumental in providing off-the-grid refrigeration, usually by means of a gas absorption refrigerator.

Blends of pure, dry "isopropane" (R-290a) (isobutane/propane mixtures) and isobutane (R-600a) have negligible ozone depletion potential and very low Global Warming Potential (having a value of 3.3 times the GWP of carbon dioxide) and can serve as a functional replacement for R-12, R-22, R-134a, and other chlorofluorocarbon or hydrofluorocarbon refrigerants in conventional stationary refrigeration and air conditioning systems.

In motor vehicles

Such substitution is widely prohibited or discouraged in motor vehicle air conditioning systems, on the grounds that using flammable hydrocarbons in systems originally designed to carry non-flammable refrigerant presents a significant risk of fire or explosion.

Other uses

• Propane is the primary flammable gas in blowtorches for soldering or brazing.
• Propane is used as a feedstock for the production of base petrochemicals in steam cracking.
• Propane is the primary fuel for hot air balloons.
• It is used in semiconductor manufacture to deposit silicon carbide.
• Propane is commonly used in theme parks and in the movie industry as an inexpensive, high-energy fuel for explosions and other special effects.
• Propane is used as a propellant, relying on the expansion of the gas to fire the projectile. It does not ignite the gas. The use of a liquefied gas gives more shots per cylinder, compared to a compressed gas.
• Propane is used as a propellant for many household aerosol sprays, including shaving creams and air fresheners.

Is propane safe to use?

 Unlike natural gas, propane is denser than air. It may accumulate in low spaces and near the floor. When abused as an inhalant, it may cause hypoxia (lack of oxygen), pneumonia, or cardiac failure or arrest. Propane has low toxicity since it is not readily absorbed and is not biologically active. Commonly stored under pressure at room temperature, propane and its mixtures will flash evaporate at atmospheric pressure and cool well below freezing. The cold gas, which appears white due to moisture condensing from the air, may cause frostbite.

Propane is denser than air. If a leak in a propane fuel system occurs, the gas will have a tendency to sink into any enclosed area and thus poses a risk of explosion and fire. The typical scenario is a leaking cylinder stored in a basement; the propane leak drifts across the floor to the pilot light on the furnace or water heater, and results in an explosion or fire. This property makes propane generally unsuitable as a fuel for boats.

A hazard associated with propane storage and transport is known as a BLEVE or boiling liquid expanding vapor explosion. The Kingman Explosion involved a railroad tank car in Kingman, Arizona in 1973 during a propane transfer. The fire and subsequent explosions resulted in twelve fatalities and numerous injuries.

Safety features while using propane

Propane as a Fuel

• Propane is non-toxic – it will not contaminate the soil or the surrounding environment. 
• Propane is odourized – an odourant called Ethyl Mercaptan is added to propane so that leaks are easily detected. 
• Propane is lead-free. 
• Propane contains extremely low levels of sulphur. 
• Propane has the lowest flammability range of all alternative fuels (2.4 – 9.5%) – so there must be the right combination of propane and oxygen, if there is too much or too little propane it will not burn. 
• Propane’s ignition temperature is approximately 920° - 1020°F, gasoline’s ignition temperature is 495°F – therefore, gasoline will burn or explode at a much lower temperature than propane.

Propane Cylinders

• Propane tanks must be equipped with a pressure relief valve that opens and closes to prevent excessive internal pressure due to abnormal conditions.
• The 2007 edition of the Propane Storage and Handling Code introduced a new requirement that cylinders, of 40lbs propane capacity and less be equipped with an Overfill Protection Device (OPD). The OPD is certified as a secondary device and is meant as a back stop device in case the attendant accidently tries to overfill the cylinder.
• Marks are stamped onto the collar of cylinders identifying the original date of manufacture and any subsequent re-testing dates. For a diagram that explains how to read the collar, click here.
• Cylinders must be inspected and requalified every 10 years – it is against the law to fill an outdated cylinder. The disposal or requalification of a cylinder must be done by organizations that have the appropriate equipment, training and certification to do so, and which have been certified by Transport Canada to do the work.
  • To find a requalifier in your area, go to the Transport Canada website. (Note: Select the "External Visual" cylinder requalification method (for propane cylinders).
• Never throw your propane cylinder in the garbage. To dispose of your old cylinder, drop it off at a municipal transfer station or depot that accepts propane cylinders. Your propane supplier may also accept cylinders for disposal. Please click here for a list of the various programs in each province.
• Personnel are required by law to have a record of training (ROT) to fill propane tanks and cylinders (transfer propane from one container to another)
• The Propane Training Institute, a division of the CPA, offers over 30 propane-related courses and issues over 30,000 training certificates annually.

Propane Vehicles

• Propane is the most commonly used alternative transportation fuel in Canada.
• Worldwide there are over 25 million vehicles powered by propane.
• Propane tanks are 20 times more puncture-resistant than gasoline tanks – which makes them less likely to rupture in an accident.
• Propane tanks used in vehicles are equipped with a stop-fill valve that stops the filling process when the tank reaches 80% of its liquid capacity, which allows room for volume changes due to temperature variations.
• Propane engine fuel systems are fitted with safety devices and shut-off valves that function automatically to prevent the escape of propane if the fuel line ruptures in an accident. 
• Onboard gas detectors and other safety valves allow fuel to flow only when the engine is operating.
• If the vehicle should catch fire in the event of an accident, the propane tank is designed to control its pressure via a pressure relief valve, saving the tank from rupturing and causing further damage.

Standards & Regulations

Strict standards and regulations are in place to govern the production, storage, transportation and use of propane to ensure your safety.  For more information, please see our Regulatory Overview page.

Safety Tips

The following safety tips and fact sheets are provided for information purposes only. Always consult with a qualified professional for clarification on particular equipment or requirements in your jurisdiction.

Barbecue Safety

Whether you are looking for information on taking your barbecue out of storage in the spring, checking for leaks, lighting the barbecue or changing the cylinder, our Barbecue Safety Fact Sheet is provided to help you operate your barbecue safely.

Carbon Monoxide

Carbon monoxide, commonly known as CO, is a colourless, odourless and tasteless toxic gas. Propane appliances, like all other fuel-burning appliances, can present the risk of carbon monoxide (CO) poisoning if not installed, operated, vented or maintained properly. Even a small amount of CO is dangerous in enclosed spaces like your home, garage, vehicle, cottage, boat, recreational vehicle or tent.
To prevent carbon monoxide poisoning, it is important to ensure your family is informed of the symptoms and causes of CO poisoning, as well as the precautions you can take. Find out more by reading our Carbon Monoxide Safety Fact Sheet.

Storage & Handling

Propane is stored and used in sealed containers and fuel systems, and is only transferred from one container to another by trained personnel. Please see our Storage & Handling Safety Fact Sheet for information including:

• Basic Safety Considerations
• The Rules for Transportation
• Choosing the Correct Propane Containers
• Protecting Your Regulator and Connectors
• Securing Propane Containers Properly on RVs and Campers

RVs and Campers

If you and your family use a recreational vehicle (R.V.) or camper it is important to ensure all users are familiar with the manufacturer's written operating and maintenance instructions. If you are renting, ask for safety instructions. Use the same care and diligence when tending to the propane systems in your R.V. or camper as you would for those in your home or business.  With respect to regulations specific to the use of R.V.s and campers in Canada:

• In many provinces, regular inspection of the propane system on board by a qualified service technician is mandatory.
• In most provinces, it's law that all appliances and pilot lights must be turned off and cylinder valves closed while travelling.

Contact the provincial Motor Vehicle Branch where you own, rent or operate an R.V. or camper to inquire about requirements that may apply to you.

Safety At Home and Work

The propane inside a container is in liquid form with a vapour space above the liquid. Propane turns to vapour (gas) when it is released from the container. Liquid propane can cause severe frostbite if it comes in contact with your skin or eyes. Keep your head away from the valves on your tank or cylinder. A sudden release of propane liquid/vapour from the pressure relief valve could result in serious injury.

Propane can be ignited by many sources including pilot lights, open flames, smoking materials, electric sparks, and static electricity. Ignition of propane gas within an enclosed space can result in an explosion.

Please see our Safety at Home and Work Fact Sheet which includes information on:

• Checking for Leaks Regularly
• What to Do If You Run Out of Gas
• Using and Maintaining Appliances as Directed
• Calling Before You Dig
• What to do if you suspect a gas leak
• Importance of regular inspections

Other important things to know about propane safety at home:

Be Familiar with Propane's Odour

When produced, propane is both colourless and odourless. An odourant called Ethyl Mercaptan is added so, in the event of a leak, you can detect the escaping gas by its strong, distinct smell (like rotten eggs, a skunk, or boiling cabbage). Ask your propane supplier to familiarize you and your family with this smell. If you think the odour of your propane gas is weak, call your propane supplier.

You may also consider the purchasing of a propane gas detector – ensure it is certified by the Canadian Standards Association (CSA) or Underwriters Laboratories of Canada (ULC). But remember, it should never be relied upon as a substitute for regular inspection and maintenance of propane appliances. If you smell propane in or outside your home, no matter how faint, always treat it as an emergency, whether the detector’s alarm is ringing or not.

Know How to Shut Off Your Propane Supply

If it is safe to do so, in an emergency, such as a flood or a leak for example, it may be necessary or prudent to shut off your propane supply before your propane supplier or first responder (i.e. Fire Department) arrives. Depending on the situation, you may require a visit from a qualified service technician to turn the gas back on, check for leaks and turn on the pilot lights. It is important that you know the proper procedures for turning the propane supply on and off – safety first! Contact your propane supplier for instructions.

Know How to Change Your Cylinder

Whether it’s for your barbecue, your R.V. of for any another appliance for which you have a portable cylinder attached, the time will come when it’s time for a refill or replacement. Here are the steps to follow when it’s time to change your cylinder to ensure it is done safely:

1. Make sure all pilot lights and appliance valves are shut off and there are no open lines.
   • If changing a cylinder on a barbecue, make sure the lid is open and the burner valves are closed.
   • If changing a mounted R.V. or camper cylinder, complete this step BEFORE entering the refuelling area. Then turn off the vehicle engine and have all passengers leave the R.V. or camper.
2. Shut off the cylinder service valve supplying propane to the system.
3. Disconnect the cylinder and remove for refilling or replacement.
4. Older models have a POL (prest-o-lite) fitting with a left-hand thread that will require the use of a properly sized wrench.
5. Cylinders equipped with a black plastic nut turn counter-clockwise to loosen and turn clockwise to tighten.
6. Install the attached protective plug or cap to the service valve outlet if transporting the cylinder.
7. If your connector POL fitting requires a rubber “O” ring, replace it if it is worn or missing.
8. Prior to reconnecting the cylinder to the service line, secure the cylinder in a cabinet or bracket and remove the protective plug or cap.
9. Reconnect the cylinder to the service line.
10. Slowly turn on the cylinder service valve only and ensure appliance/burner valves remain closed.
11. Check for leaks.
12. If pilot lights are involved, after you’re sure the system is leak-free and the controls are operating properly, the pilots can be relit following manufacturer’s instructions.

Weather-Related Safety Tips

For safety procedures when flooding is predicted, please see our Flooding Safety Fact Sheet.
The Propane Education and Research Council (PERC) in the U.S. has made available a number of other weather-related safety documents on their consumer website such as thunderstorms, extreme heat and winter storms, that contain valuable information applicable for Canadians as well.

 How does propane compare to other froms of energy?

Propane can be up to 25% less expensive than electricity in most cities. In addition, when tank levels are properly maintained, propane provides a virtually uninterruptible power supply. That is reassuring when “brownouts” or “blackouts” occur when too many users are drawing electricity during high consumption periods, like cold winter months.

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Is propane really a convenient fuel?

Yes. Propane is stored in portable tanks, so it can be used in areas beyond the natural gas mains. When used in vehicles, propane is also easily replenished and refuels at 10 gallons to 12 gallons per minute, similar to gasoline. More than 10,000 propane-refueling sites are available across the country.

Is propane dangerous to the environment?

 No. Propane is an approved, alternative clean fuel listed in the 1990 Clean Air Act and the National Energy Policy Act of 1992. Propane is one of the cleanest burning of all alternative fuels; new propane-fueled vehicles can meet the very tough Ultra-Low Emission Vehicle (ULEV) standards, and one model even meets the Super Ultra-Low Emission Vehicle (SULEV) standards. Propane is also nontoxic, so it’s not harmful to soil or water.