The terms LPG, propane, and butane might seem interchangeable, but while they share commonalities, each serves distinct purposes and has unique properties. It is essential to understand these before you fuel up any piece of lawn care equipment to ensure that you have chosen the right one for your machinery.
Keep reading to discover the differences and why they matter from the Hughie Willett Machinery team…
What is LPG?
To kick things off, we will look at defining LPG.
Liquefied Petroleum Gas - or LPG - is a fuel type that has become an integral part of our daily lives. This specific product is a mixture of hydrocarbon gases, primarily composed of propane (C₃H₈) and butane (C₄H₁₀), which are by-products of natural gas processing and petroleum refining. The reason it's called “liquefied” is that it can be easily converted into a liquid form under moderate pressure or at low temperatures, which makes it more convenient for storage and transportation.
From a chemical standpoint, LPG is composed of saturated hydrocarbons, meaning they have single bonds between carbon atoms. This makes them relatively stable and less reactive compared to unsaturated hydrocarbons, which have double or triple bonds.
LPG is popular because of its clean-burning properties. When it burns, it produces relatively low levels of carbon dioxide (CO₂) and other pollutants compared to other fossil fuels, which makes it a popular choice for a variety of applications.
Another key advantage of LPG is its high energy content. It provides a substantial amount of heat per unit of fuel, making it an efficient energy source.
What are propane and butane?
Propane and butane are two of the primary components of LPG.
Propane is a three-carbon alkane with the chemical formula C₃H₈. It is a gas at standard temperature and pressure, but can be liquefied under moderate pressure. Propane's boiling point is -42 °C, which means it remains a gas even in very cold environments.
Its high energy content and clean-burning nature make it a popular choice for both residential and commercial applications, and is commonly used in heating systems, grills, and portable stoves.
Butane, on the other hand, is a four-carbon alkane with the chemical formula C₄H₁₀. It has a higher boiling point of -0.5 °C, which means it can be easily liquefied at room temperature.
This property makes butane suitable for use in portable applications where storage in low-pressure containers is advantageous, such as lighters, portable stoves, and as a propellant in aerosol sprays.
In terms of chemical properties, both propane and butane are relatively stable, non-toxic, and colourless gases. They are odourless in their pure form, but for leak detection purposes in LPG, an odourant, such as ethyl mercaptan, is added to give it a distinctive smell.
Energy content
Now that we’ve covered the differences between LPG, propane, and butane, let’s look at how the three compare in different categories, starting with their energy content.
LPG
LPG has an average calorific value of around 50 MJ/kg (megajoules per kilogram). This high energy content makes LPG a highly efficient fuel for various applications. The precise calorific value of LPG can vary based on the ratio of propane to butane in the mixture, but it consistently offers a robust energy output.
The efficiency of LPG as a fuel is further improved by its clean-burning properties, which results in fewer emissions of pollutants and greenhouse gases when compared to traditional fossil fuels.
Propane
Propane has a calorific value of approximately 50.35 MJ/kg, which delivers more energy per unit of fuel compared to butane. This higher energy density is contributed to the molecular structure of propane, with three carbon atoms and eight hydrogen atoms (C₃H₈).
The efficiency of propane is further amplified by its ability to remain gaseous at lower temperatures, ensuring consistent energy delivery even in colder conditions. The higher calorific value makes propane a more energy-dense fuel, providing substantial heat output for a given volume or mass.
Butane
Butane, with a calorific value of around 49.52 MJ/kg, is slightly lower in energy content compared to propane, due to the molecular composition consisting of four carbon atoms and ten hydrogen atoms (C₄H₁₀).
However, it is highly efficient for specific applications. Its ease of liquefaction at room temperature allows for compact and convenient storage in low-pressure containers. While butane releases slightly less energy per kilogram compared to propane, its performance is improved in conditions where moderate temperatures are maintained.
Storage and transportation
The storage and transportation of LPG, propane, and butane are critical aspects to consider, as each gas has specific requirements which must be meticulously observed.
LPG
As it is a mixture of propane and butane, LPG is stored in pressurised tanks or cylinders. These containers are usually made of steel or aluminium and are designed to maintain the LPG in a liquid state under moderate pressure.
The pressure inside LPG tanks is carefully managed, with safety mechanisms such as pressure relief valves to prevent accidents in case of excessive pressure build-up.
Propane
Propane's ability to stay gaseous at low temperatures makes storage in various climates much easier, which is why it is such a reliable fuel source even in the harshest winter conditions.
To ensure it can be used efficiently, propane is stored in pressurised tanks or cylinders designed to withstand high pressures. These tanks can maintain the liquid state of propane under moderate pressure, with pressures inside propane tanks reaching up to 200 psi (pounds per square inch) at 37.8 °C (100 °F).
Butane
Since it has a higher boiling point of -0.5 °C, butane can be stored in low-pressure containers. These containers aren’t as robust as propane tanks because butane liquefies at lower pressures, which makes butane storage more straightforward and cost-effective in milder climates.
However, butane can become ineffective in colder environments due to its higher boiling point, limiting its use in such conditions.
Common applications
LPG, propane and butane, are used in a wide array of applications spanning multiple sectors. Let’s explore how each can be used in various scenarios.
LPG
LPG is a highly versatile fuel used extensively across residential, commercial, and industrial sectors.
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In homes: LPG powers central heating systems, from space heaters and water heaters, to hobs and ovens. Its clean-burning nature makes it an environmentally-friendly choice for households.
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In the automotive sector: LPG - commonly known as autogas - functions as a low emission alternative to petrol and diesel. Many vehicles in the UK are equipped with LPG conversion kits, which allows them to switch between petrol and LPG.
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In the culinary world: commercial kitchens use it for a consistent and controllable heat output, which is essential for high-demand cooking environments. Additionally, food vans and outdoor caterers benefit from its portability.
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In the industrial industry: LPG is used for processes like metal cutting, welding, and brazing, where a high-temperature, clean-burning fuel is vital. It also functions well in manufacturing to power machinery and production lines.
Propane
Propane is a popular fuel choice for a wide range of applications, particularly in residential, industrial, and agricultural settings. Its high energy content and ability to remain gaseous at low temperatures make it ideal for residential heating. In the kitchen, propane powers hobs, ovens, and barbecues, for a consistent and controllable heat.
In industrial applications, propane is used as a fuel for forklifts, agricultural equipment, and various machinery, reducing engine maintenance and extending equipment lifespan due to its clean-burning properties.
Propane is also used in metal cutting and brazing operations where precise, high-temperature heat is required. On farms, it is an essential component for grain drying, pest control, and heating livestock barns.
Butane
Butane has unique properties that make it an ideal fuel for portable applications, chemical production, and refrigeration. The ease of liquefaction at room temperature allows it to be used in compact and convenient storage in low-pressure canisters.
Butane is also widely used in lighters, and camping stoves, providing a light, steady flame. In the chemical industry, butane serves as a feedstock for the production of plastics, including butadiene, a key component in synthetic rubber.
It is also used as a propellant in aerosol sprays due to its ability to liquefy easily under pressure; and as a refrigerant in certain cooling applications, thanks to its low boiling point and efficiency in heat transfer.
Environmental Impact
LPG (Liquefied Petroleum Gas), propane, and butane all offer significant environmental benefits over traditional fossil fuels:
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LPG is considered a cleaner alternative to other fossil fuels such as coal and oil, as it produces lower levels of carbon dioxide, nitrogen oxides, and particulate matter. The combustion process also results in less unburned hydrocarbons and carbon monoxide, and its high energy density means that less fuel is required to produce the same amount of energy.
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Propane is specially chosen for its lower carbon content. With a carbon-to-hydrogen ratio of 3:8, propane generates less CO₂ per unit of energy produced. Plus, its clean-burning characteristics mean that it produces fewer pollutants and particulate matter. The efficient combustion of propane also results in less formation of ground-level ozone.
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Butane still offers environmental advantages over traditional fossil fuels, despite having a higher carbon content than propane. Its combustion produces lower levels of CO₂, NOₓ, and particulate matter, and the higher boiling point of butane means it is often used in enclosed or controlled environments, where its emissions can be managed more effectively.
Meet your gas needs at Hughie Willett Machinery
If you are in need of fuel for heating, lighting, or cooking then why not check out our collection of LPG or propane and butane gas at Hughie Willett? With various propane and butane bottle sizes available, call us today to confirm your size and price.
We have decades of experience providing high-quality ground care equipment at Hughie Willett Machinery. We believe you should never compromise on quality, which is why we only offer you the best products from industry-leading manufacturers.
Shop LPG, butane, and propane gas bottles today
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