If You’re in HVAC Training, Here’s What You Should Know About Fuel Gases

December 17, 2019

hvac technician training

Fuel gases help fuel heating systems, provide energy for transportation, and are used for welding—but what are they, really? Fuel gases are gases that, when mixed with oxygen or air, become combustible. They can apply to several different processes, and can be used for a number of different industrial applications. Since it’s very important for students training to become an HVAC technician to know how to practice the safest possible gas-handling procedures, learning the basics about fuel gases is a good idea.

While there’s a lot to learn about fuel gases, it’s worth knowing some of the basics beforehand, so that students have a solid idea of how fuel gases apply to heating. Here’s what students in HVAC training should know.

HVAC School Students Should Familiarize Themselves With the Different Types Used

One of the most important things to remember about fuel gases is that there are a number of different types that can be used. Some of the most commonly used are hydrogen, carbon monoxide, and ethylene. However, we’ll be focusing specifically on acetylene, methane, propane, and propylene. These four in particular are worth remembering for those in HVAC training, because each of them are comprised of hydrocarbons, either partially or in full.

Acetylene is considered the most efficient and productive fuel gas, producing the hottest and most concentrated flame. It can also be used for both welding and cutting, the only kind of commercial fuel gas that can do so. Methane is what natural gas is primarily made of, and is most often used for heating. Its combustion properties can also vary, and can be used for cutting purposes in some cases.

Acetylene is the fuel gas producing the hottest flame, and can be used for both cutting and welding
Acetylene is the fuel gas producing the hottest flame, and can be used for both cutting and welding

Propane has a lower flame temperature than acetylene when mixed with oxygen, and has the lowest flammability range among the most common fuel gases, but can be used for various purposes such as heating, brazing, melting and drying. Lastly, propylene’s double bond means it burns hotter and has a higher flame temperature than propane, and is often used during situations that call for a higher process performance.

Propane has a relatively low flame temperature and flammability range
Propane has a relatively low flame temperature and flammability range

Different Fuel Gases Have Different Heating Values and Other Properties Between Them

Since a big part of HVAC school involves learning about fuel gases and their respective characteristics and properties, it’s worth familiarizing yourself with the different heat values between each type of fuel gas. For example, acetylene has a gross heating value of 1,498 btu/ft3 and 21,569 btu/lb (British thermal units per cubic feet and pounds). Meanwhile, propane has a gross heating value of 2,572 btu/ft3 and 21,564 btu/lb, and propylene has 2,336 btu/ft3 and 21,042 btu/lb. Therefore, acetylene needs much less than propane or propylene to produce the necessary heat.

It’s also worth remembering that fuel gases each have different carbon to hydrogen atom ratios. This means that the efficient burning of the gas will require various amounts of oxygen to be used depending on the fuel gas type. Furthermore, some fuel gases are natural, while others are manufactured. Natural fuel gas largely consists of methane, while gases like ethane, propane and butane are considered natural gases. Natural gas is also considered the most commonly used fuel gas type today. Meanwhile, manufactured types of fuel gases include hydrogen, acetylene, biogas, coal gas, and blast furnace gas among others.

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