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What is LPG or LP Gas?

LPG or LP Gas is Liquefied Petroleum Gas. This is a general description of Propane (chemical formula C3H8) and Butane (chemical formula C4H10), either stored separately or together as a mix.

Why is it called Liquefied Petroleum Gas?

This is because these gases can be liquefied at normal temperature by application of a moderate pressure increase, or at normal pressure by application of cooling using refrigeration.

Where does LPG come from?

LPG comes from two sources. It occurs naturally in oil and gas fields and is separated from the other components during the extraction process from the oil or gas field. LPG is also one of the by-products of the oil refining process.

What is LPG used for?

LPG is used as a fuel for domestic, industrial, horticultural, agricultural, cooking, heating and drying processes. LPG can be used as an automotive fuel or as a propellant for aerosols, in addition to other specialist applications. LPG can also be used to provide lighting through the use of pressure lanterns.

What are the advantages of LPG?

The advantages of LPG are as follows:

• Because of it's relatively few components, it is easy to achieve the correct fuel to air mix ratio that allows the complete combustion of the product. This gives LPG it's clean burning characteristics.
• Both Propane and Butane are easily liquefied and stored in pressure containers. These properties make the fuel highly portable, and hence, can be easily transported in cylinders or tanks to end-users.
• LPG is a good substitute for petrol in spark ignition engines. Its clean burning properties, in a properly tuned engine, give reduced exhaust emissions, and extended lubricant and spark plug life.
• As a replacement for aerosol propellants and refrigerants, LPG provides alternatives to fluorocarbons which are known to cause deterioration of the earth's ozone layer.
• The clean burning properties and portability of LPG provide a substitute for indigenous fuels such as wood, coal, and other organic matter. This provides a solution to de-forestation and the reduction of particulate matter in the atmosphere (haze), caused by burning the indigenous fuels.

What are the Properties of LPG?

LPG is:

• Colourless.
• Odourless. (It's normal to odorise LPG by adding an odorant prior to supply to the user, to aid the detection of any leaks).
• Flammable.
• Heavier than air.
• Approximately half the weight of water.
• Non toxic but can cause asphyxiation.
• LPG expands upon release and 1 litre of liquid will form approximately 250 litres of vapour.

Is there any difference between LP Gas supplied from different companies?

Yes, depending on the source of supply, the quality of the LP Gas will vary. Users should seek an LP Gas supplier who will provide LP Gas which meets the local or country LP Gas specification.

Why does the price of LP Gas change during the year?

LP Gas is a commodity which varies in price, depending on the supply conditions. The demand and supply availability of LP Gas causes this price change. It is normal that the price of LP Gas should rise during the winter as the increased demand reduces product availability, and that LP Gas prices should ease during the summer.

Sometimes I see condensate or ice forming on the outside surface of the LPG cylinder. What causes this?

This is called 'sweating', and is caused by the process of LPG changing from its liquid state to a vapour state. LPG in a stable state consists of both liquid and vapour. When vapour is drawn from the cylinder the vapour pressure in the cylinder is reduced and alters this stability between the vapour pressure and the pressure required maintaining the LPG as a liquid. In this condition, the liquid LPG boils releasing vapour which stabilises the pressure within the cylinder. In order for LPG to boil, it must draw in heat through the cylinder wall. As this happens the wall of the cylinder is cooled and moisture in the air condenses on the wall of the cylinder. In extreme cases, the cylinder may have ice forming on the surface of the cylinder. Interestingly, the top edge of the sweating or ice, reveals the level of the LPG remaining in the cylinder.

How can I tell how much LPG is left in the cylinder?

There are a number of ways to check this:

• Firstly, a cylinder can be weighed to check how much product is left in the cylinder. The weight of the LPG remaining in the cylinder is total weight of the cylinder plus the LPG, less the empty weight or tare weight, of the cylinder. (The regulator and any other fittings should be removed prior to weighing the cylinder).
• Secondly, some cylinders have gauges which show the amount of LPG contained within the cylinder.
• Thirdly, liquid crystal gauges, which stick to the outer surface of the LPG cylinder are available, and these show the level of the liquid LPG within the cylinder by indicating a colour change at the interface between the liquid and vapour levels caused by the temperature variation.
• Fourthly, if the cylinder is being used, then it may be possible to see the level of the LPG in the cylinder by observing the level of the sweating on the cylinder wall.
• Lastly, it is possible to see the level of the LPG liquid within a cylinder by pouring boiling water down the side of the LPG cylinder. The liquid level is revealed where a condensate or frost line occurs.

Sometimes the flame on the appliance is not at a constant height and varies. Why does this happen?

This can be caused by several reasons:

• The cylinder is low on LPG and will need refilling soon.
• The draw-off rate is greater than the cylinder can deliver.
• The regulator is wrongly sized for your application.

In all cases you should contact your supplier for a refill, or inform your supplier about the application requirements.

How do I know that my supplier is providing me with the correct weight of LPG?

Always ensure that the cylinder has the company seal fitted and has not been tampered with. You can weigh the cylinder and verify that you have purchased the amount that the cylinder contains. The total weight, less the weight of the cylinder, known as the Tare Weight, is the amount of LPG that you have purchased. Note that generally the tare weight (TW), is stamped onto the valve protection ring or painted onto the cylinder.

Where should I store my LP Gas cylinder?

Your LP Gas cylinder should be stored in a location which is well ventilated and accessible so that it is easy to change. Remember that the hose connection to the appliance should not be excessively long as this will make the hose prone to damage. In addition the LP Gas cylinder should not be in direct sunlight or located close to any direct heat source such as an open fire. Always ensure that the LP Gas cylinder is stored in an upright position.

How should I select my LPG supplier?

Of course you will want the best price, but you should select your LPG provider on the basis of someone who will provide the services that you require.

• Cylinder delivered at the time it was promised.
• Cylinders well maintained and the valve sealed, assuring that the quantity of LPG that you were charged for is in the cylinder.
• The provider should be knowledgeable to assist you with any LPG supply or appliance problems both during business hours and outside normal business hours.
• The provider should also be aware of your usage and be proactive in providing a replacement cylinder.

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