How Gases Are Measured

The amount of gas used or sold is given by one of:

• Kilogram (kg) - only for gases that are stored as liquids.
• Cubic metre (m3) - Since gas is compressible, we specify standard temperature and pressure.
• Megajoule (MJ) - this is the amount of energy it contains. 1 kilowatt hour equals 3.6 Megaj'oules.

The properties of gas are given by

Heating Value - Megajoules per cubic metre of gas. Propane has a heating value of 94MJ/m3, compared to Natural gas 40 MJ/ m3.

• Density - kilograms per litre of gas. Natural gas is lighter than air, so floats. LPG is denser than air, so tends to sink and form potentially explosive pools of gas near leaking appliances.

Chemical Composition Of Gas

Gas is made of small chains of carbon atoms. The simplest unit is methane - one central carbon, with four hydrogen atoms attached to it.

As you chain methane units together, you get heavier gases, such as ethane, propane and butane.

As the gas gets heavier, less pressure is required to compress it into a liquid at room temperature: methane becomes liquid under extreme pressure, propane becomes liquid at 640 kPa, and butane becomes liquid at 80 kPa.

Types of Gas

For purposes of discussing commercially useful sources of energy, the most important gases are:

• Natural gas - mostly methane, found naturally underground, often near oil reserves. Once extracted, impurities are removed, and it is piped over long distances to the end user.
• LPG (Liquefied Petroleum Gas) - a mixture of propane and butane, produced as a by-product of oil refining. It is liquefied, and sold in high pressure cylinders. These cylinders are either sold or rented to the consumer or to industrial installations.

In addition, 4 other types of gas are still in use today:

• Town gas - Originally based on coal gas, now produced from natural gas, LPG or oil. Made centrally and distributed by pipes to the end user. Largely being replaced by natural gas.
• TLP (Tempered LPG) - a mixture of LPG and air, compatible with town gas, but easier to produce.
• SNG (Simulated Natural Gas) - a mixture of LPG and air, but compatible with natural gas. Used in new estates where natural gas will soon become available.
• PNG (Processed Natural Gas) - natural gas which has been altered to make it compatible with town gas. Used in areas where there is resistance to modifying town gas appliances.

Gas Distribution

Natural gas is not universally available around Australia. Cities and regional centres differ in the penetration of natural gas, and the percentage of households and businesses that have gas connected. Whether gas becomes available to an'area is determined by an economic assessment of cost of laying pipes versus expected future revenue flows from gas appliance usage.

Since LPG is readily transportable by road and installations do not require significant capital outlay, we can regard LPG as almost universally available around Australia. However, the higher cost of LPG relative to natural gas, as well as the need to refill or exchange cylinders both tend to limit the usage of the gas.

How Natural Gas Is Sold

Owing to deregulation, gas retailing has developed in a similar way to electricity over the last few years, with most energy companies now offering both gas and electricity to consumers and businesses.

Natural Gas is typically sold by the megajoule. Most providers have different tariff structures for different purposes, such as for heating of water and space heating. Many have a block type tariff structure in which the first block of heat units in the billing period is sold at a higher tariff than subsequent blocks in order to obtain a more equitable return on basic capital costs. Still other tariffs may consist of a standing charge (to cover capital costs) and an additional charge for the gas consumed (to cover production costs).

How LPG Is Sold

Liquefied gases are typically sold by the kilogram or cubic metre. Gas suppliers may have special tariffs for special purposes or differential tariffs according to usage. In many cases the storage vessel is rented to the consumer and the value of this rental should be included as part of the cost of LPG when comparing it with other fuels.

Gas Combustion

Similar to the respiration of living organisms, gas appliances use oxygen to burn the fuel, and produce carbon dioxide and water vapour, plus minor quantities of other gases, as by-products. In the process, energy is released.

Removal Of Combustion By-Products

It is important that all by-products of gas combustion be removed not only from the combustion area but also where people or animals are breathing.

Large fixed appliances are installed with flues to remove such products from the appliances. Smaller appliances may be permitted for unflued installation, but this is only allowed where there is adequate ventilation.

Inadequate ventilation of an unflued appliance will produce undesirable or dangerous effects such as smothering of the flames, imperfect combustion, condensation on walls and ceilings, sooting, smells, and discolouration of painted surfaces or textiles.

In particular, imperfect combustion can produce excessive quantities of carbon monoxide, a colourless, odourless, invisible but highly poisonous gas. There have been cases in recent years of consumer fatalities as a result of improper combustion due to poor appliance installation or servicing. In addition, other combustion by-products such as nitrous oxides or NOx, are irritant gases and are known to exacerbate respiratory conditions such as asthma.

Detecting Improper Combustion

The easiest way to determine if a gas burner is operating correctly is to look at the flame. A well burning gas flame should be sharp and blue. A small amount of yellow tipping is permissible. Excessive yellow tipping is a sign of inadequate oxygen, which results in free carbon particles (ie not combined with oxygen) which colour the flame yellow. Concentrations of carbon monoxide will also be much higher than is safe. Since this represents significant under-combustion, the flame will be cooler than it is designed to be, resulting in lower efficiency.

Gas Appliance Certification

All gas water heaters are required to meet the Certification Requirements for Gas Appliances as published by Standards Australia. Rheem gas water heaters up to 500 MJ/h are all certified to comply with the requirements of AS4552 - Gas Water Heaters. Water heaters exceeding 500 MJ/h input comply with the requirements of AS 3814-2005 - Industrial And Commercial Gas-Fired Appliances. Certification is signified by the certifying body's unique badge.

In addition, all installations must comply with AS5601 - Gas Installations.

Gas Appliance Characteristics

Natural Gas Appliances:
In addition to the requirements for compliance and proper gas combustion, all natural gas appliances have the following properties in common:

• Must be fitted with a gas governor. This is a regulating device that prevents the build up of increased gas pressure at the appliance and over gassing of the burner.
• May operate on SNG but will not operate on town gas, PNG, TLP gas or LPG without modification.
• Designed for normal operation at a gas inlet pressure of 1.13 kPa.

LPG Appliances:
In addition to the requirements for appliance approval and proper gas combustion, all LPG appliances have the following properties in common:

• LPG appliances do not necessarily have gas governors. However, the installation will have a regulator installed near the cylinder which serves the same purpose.
• LPG appliances should be fitted with 100% safety shut off devices to stop all gas flow should the pilot flame become extinguished.
• LPG appliances are designed for normal operation at a gas supply pressure of 2.75 kPa.

Certification is available in three categories:

• propane only
• butane only
• LPG

Note: A propane only unit will not operate on butane. A butane only unit will operate on propane, but at a much reduced input. The LPG approval is normally at a much lower rating than either propane only or butane only and in effect is the propane rating of a butane only appliance.

Conversion Of Appliances For Different Gases

Due to differences in pressure and heating value between different gases, appliances which are designed for one type of gas will usually need to be converted before being connected to any other type of gas. Injector sizes and port size for both the main burner and pilots will need to be changed, and which type of gas governor (if any is needed) will also need to be considered.

Simon Totterdell - Owner

Call Now - 99043074

How Gases Are Measured

The amount of gas used or sold is given by one of:

• Kilogram (kg) - only for gases that are stored as liquids.
• Cubic metre (m3) - Since gas is compressible, we specify standard temperature and pressure.
• Megajoule (MJ) - this is the amount of energy it contains. 1 kilowatt hour equals 3.6 Megaj'oules.

The properties of gas are given by

Heating Value - Megajoules per cubic metre of gas. Propane has a heating value of 94MJ/m3, compared to Natural gas 40 MJ/ m3.

• Density - kilograms per litre of gas. Natural gas is lighter than air, so floats. LPG is denser than air, so tends to sink and form potentially explosive pools of gas near leaking appliances.

Chemical Composition Of Gas

Gas is made of small chains of carbon atoms. The simplest unit is methane - one central carbon, with four hydrogen atoms attached to it.

As you chain methane units together, you get heavier gases, such as ethane, propane and butane.

As the gas gets heavier, less pressure is required to compress it into a liquid at room temperature: methane becomes liquid under extreme pressure, propane becomes liquid at 640 kPa, and butane becomes liquid at 80 kPa.

Types of Gas

For purposes of discussing commercially useful sources of energy, the most important gases are:

• Natural gas - mostly methane, found naturally underground, often near oil reserves. Once extracted, impurities are removed, and it is piped over long distances to the end user.
• LPG (Liquefied Petroleum Gas) - a mixture of propane and butane, produced as a by-product of oil refining. It is liquefied, and sold in high pressure cylinders. These cylinders are either sold or rented to the consumer or to industrial installations.

In addition, 4 other types of gas are still in use today:

• Town gas - Originally based on coal gas, now produced from natural gas, LPG or oil. Made centrally and distributed by pipes to the end user. Largely being replaced by natural gas.
• TLP (Tempered LPG) - a mixture of LPG and air, compatible with town gas, but easier to produce.
• SNG (Simulated Natural Gas) - a mixture of LPG and air, but compatible with natural gas. Used in new estates where natural gas will soon become available.
• PNG (Processed Natural Gas) - natural gas which has been altered to make it compatible with town gas. Used in areas where there is resistance to modifying town gas appliances.

Gas Distribution

Natural gas is not universally available around Australia. Cities and regional centres differ in the penetration of natural gas, and the percentage of households and businesses that have gas connected. Whether gas becomes available to an'area is determined by an economic assessment of cost of laying pipes versus expected future revenue flows from gas appliance usage.

Since LPG is readily transportable by road and installations do not require significant capital outlay, we can regard LPG as almost universally available around Australia. However, the higher cost of LPG relative to natural gas, as well as the need to refill or exchange cylinders both tend to limit the usage of the gas.

How Natural Gas Is Sold

Owing to deregulation, gas retailing has developed in a similar way to electricity over the last few years, with most energy companies now offering both gas and electricity to consumers and businesses.

Natural Gas is typically sold by the megajoule. Most providers have different tariff structures for different purposes, such as for heating of water and space heating. Many have a block type tariff structure in which the first block of heat units in the billing period is sold at a higher tariff than subsequent blocks in order to obtain a more equitable return on basic capital costs. Still other tariffs may consist of a standing charge (to cover capital costs) and an additional charge for the gas consumed (to cover production costs).

How LPG Is Sold

Liquefied gases are typically sold by the kilogram or cubic metre. Gas suppliers may have special tariffs for special purposes or differential tariffs according to usage. In many cases the storage vessel is rented to the consumer and the value of this rental should be included as part of the cost of LPG when comparing it with other fuels.

Gas Combustion

Similar to the respiration of living organisms, gas appliances use oxygen to burn the fuel, and produce carbon dioxide and water vapour, plus minor quantities of other gases, as by-products. In the process, energy is released.

Removal Of Combustion By-Products

It is important that all by-products of gas combustion be removed not only from the combustion area but also where people or animals are breathing.

Large fixed appliances are installed with flues to remove such products from the appliances. Smaller appliances may be permitted for unflued installation, but this is only allowed where there is adequate ventilation.

Inadequate ventilation of an unflued appliance will produce undesirable or dangerous effects such as smothering of the flames, imperfect combustion, condensation on walls and ceilings, sooting, smells, and discolouration of painted surfaces or textiles.

In particular, imperfect combustion can produce excessive quantities of carbon monoxide, a colourless, odourless, invisible but highly poisonous gas. There have been cases in recent years of consumer fatalities as a result of improper combustion due to poor appliance installation or servicing. In addition, other combustion by-products such as nitrous oxides or NOx, are irritant gases and are known to exacerbate respiratory conditions such as asthma.

Detecting Improper Combustion

The easiest way to determine if a gas burner is operating correctly is to look at the flame. A well burning gas flame should be sharp and blue. A small amount of yellow tipping is permissible. Excessive yellow tipping is a sign of inadequate oxygen, which results in free carbon particles (ie not combined with oxygen) which colour the flame yellow. Concentrations of carbon monoxide will also be much higher than is safe. Since this represents significant under-combustion, the flame will be cooler than it is designed to be, resulting in lower efficiency.

Gas Appliance Certification

All gas water heaters are required to meet the Certification Requirements for Gas Appliances as published by Standards Australia. Rheem gas water heaters up to 500 MJ/h are all certified to comply with the requirements of AS4552 - Gas Water Heaters. Water heaters exceeding 500 MJ/h input comply with the requirements of AS 3814-2005 - Industrial And Commercial Gas-Fired Appliances. Certification is signified by the certifying body's unique badge.

In addition, all installations must comply with AS5601 - Gas Installations.

Gas Appliance Characteristics

Natural Gas Appliances:
In addition to the requirements for compliance and proper gas combustion, all natural gas appliances have the following properties in common:

• Must be fitted with a gas governor. This is a regulating device that prevents the build up of increased gas pressure at the appliance and over gassing of the burner.
• May operate on SNG but will not operate on town gas, PNG, TLP gas or LPG without modification.
• Designed for normal operation at a gas inlet pressure of 1.13 kPa.

LPG Appliances:
In addition to the requirements for appliance approval and proper gas combustion, all LPG appliances have the following properties in common:

• LPG appliances do not necessarily have gas governors. However, the installation will have a regulator installed near the cylinder which serves the same purpose.
• LPG appliances should be fitted with 100% safety shut off devices to stop all gas flow should the pilot flame become extinguished.
• LPG appliances are designed for normal operation at a gas supply pressure of 2.75 kPa.

Certification is available in three categories:

• propane only
• butane only
• LPG

Note: A propane only unit will not operate on butane. A butane only unit will operate on propane, but at a much reduced input. The LPG approval is normally at a much lower rating than either propane only or butane only and in effect is the propane rating of a butane only appliance.

Conversion Of Appliances For Different Gases

Due to differences in pressure and heating value between different gases, appliances which are designed for one type of gas will usually need to be converted before being connected to any other type of gas. Injector sizes and port size for both the main burner and pilots will need to be changed, and which type of gas governor (if any is needed) will also need to be considered.

Simon Totterdell - Owner

Call Now - 99043074