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Lifting gas
A lifting gas or lighter-than-air gas is a gas that has a density lower than normal atmospheric gases and rises above them as a result, making it useful in lifting lighter-than-air aircraft. Only certain lighter-than-air gases are suitable as lifting gases. Dry air has a density of about 1.29 g/L (gram per liter) at standard conditions for temperature and pressure (STP) and an average molecular mass of 28.97 g/mol, and so lighter-than-air gases have a density lower than this.
Heated atmospheric air is frequently used in recreational ballooning. According to the ideal gas law, an amount of gas (and also a mixture of gases such as air) expands as it is heated. As a result, a certain volume of gas has a lower density as its temperature increases. The temperature of the hot air in the envelope will vary depending upon the ambient temperature, but the maximum continuous operating temperature for most balloons is 250 °F (121 °C).
Hydrogen, being the lightest existing gas (7% the density of air, 0.08988 g/L at STP), seems to be the most appropriate gas for lifting. It can be easily produced in large quantities, for example with the water-gas shift reaction or electrolysis, but hydrogen has several disadvantages:
Helium is the second lightest gas (0.1786 g/L at STP). For that reason, it is an attractive gas for lifting as well.
A major advantage is that this gas is noncombustible. But the use of helium has some disadvantages, too:
In the past, coal gas, a mixture of hydrogen, carbon monoxide, and other gases, like Blau gas, was also used in balloons.[better source needed] It was widely available and cheap. Disadvantages include a higher density (reducing lift), its flammability and the high toxicity of the carbon monoxide content.
Ammonia has been used as a lifting gas in balloons, but while inexpensive, it is relatively heavy (density 0.769 g/L at STP, average molecular mass 17.03 g/mol), poisonous, an irritant, and can damage some metals and plastics.
Methane (density 0.716 g/L at STP, average molecular mass 16.04 g/mol), the main component of natural gas, is sometimes used as a lift gas when hydrogen and helium are not available.[citation needed] It has the advantage of not leaking through balloon walls as rapidly as the smaller molecules of hydrogen and helium. Many lighter-than-air balloons are made of aluminized plastic that limits such leakage; hydrogen and helium leak rapidly through latex balloons. However, methane is highly flammable and like hydrogen is not appropriate for use in passenger-carrying airships. It is also relatively dense and a potent greenhouse gas.
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Lifting gas AI simulator
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Lifting gas
A lifting gas or lighter-than-air gas is a gas that has a density lower than normal atmospheric gases and rises above them as a result, making it useful in lifting lighter-than-air aircraft. Only certain lighter-than-air gases are suitable as lifting gases. Dry air has a density of about 1.29 g/L (gram per liter) at standard conditions for temperature and pressure (STP) and an average molecular mass of 28.97 g/mol, and so lighter-than-air gases have a density lower than this.
Heated atmospheric air is frequently used in recreational ballooning. According to the ideal gas law, an amount of gas (and also a mixture of gases such as air) expands as it is heated. As a result, a certain volume of gas has a lower density as its temperature increases. The temperature of the hot air in the envelope will vary depending upon the ambient temperature, but the maximum continuous operating temperature for most balloons is 250 °F (121 °C).
Hydrogen, being the lightest existing gas (7% the density of air, 0.08988 g/L at STP), seems to be the most appropriate gas for lifting. It can be easily produced in large quantities, for example with the water-gas shift reaction or electrolysis, but hydrogen has several disadvantages:
Helium is the second lightest gas (0.1786 g/L at STP). For that reason, it is an attractive gas for lifting as well.
A major advantage is that this gas is noncombustible. But the use of helium has some disadvantages, too:
In the past, coal gas, a mixture of hydrogen, carbon monoxide, and other gases, like Blau gas, was also used in balloons.[better source needed] It was widely available and cheap. Disadvantages include a higher density (reducing lift), its flammability and the high toxicity of the carbon monoxide content.
Ammonia has been used as a lifting gas in balloons, but while inexpensive, it is relatively heavy (density 0.769 g/L at STP, average molecular mass 17.03 g/mol), poisonous, an irritant, and can damage some metals and plastics.
Methane (density 0.716 g/L at STP, average molecular mass 16.04 g/mol), the main component of natural gas, is sometimes used as a lift gas when hydrogen and helium are not available.[citation needed] It has the advantage of not leaking through balloon walls as rapidly as the smaller molecules of hydrogen and helium. Many lighter-than-air balloons are made of aluminized plastic that limits such leakage; hydrogen and helium leak rapidly through latex balloons. However, methane is highly flammable and like hydrogen is not appropriate for use in passenger-carrying airships. It is also relatively dense and a potent greenhouse gas.