Characteristics of Gas

Natural Gas

Natural gas has the chemical formula of CH4. Natural gas, also known as processed natural gas, is a dry gas which means it has all the heavier hydrocarbons removed and stored in underground storage tanks for use. Natural gas has no color, no taste, no odor (your distributor adds mercaptan for safety which gives a rotten egg smell), is non-toxic (although you may die from insufficient oxygen if there is too much natural gas in the air), and is transparent.

The specific gravity of natural gas is .55, although some go by .6. This means a weight of a volume of a vapor gas weighs less than an equal volume of air. This is why when you have a natural gas leak, the vapor will rise towards the ceiling since the gas weighs less than air.

The ignition temperature for natural gas is between 1200°F and 1300°F, and the limits of flammability are 4% to 15%. This means if you have below 4% natural gas in the air, combustion cannot happen. Likewise, if you have above 15% gas in the air combustion cannot occur either. Opening a window during a gas leak can be dangerous due to this.

The products of incomplete combustion are carbon monoxide and aldehydes.

Aldehydes are irritating to the eyes, throat, and nose. They smell terrible. Aldehydes taste somewhat metallic and are likely accompanied by carbon monoxide.

Carbon monoxide (CO) is the most harmful product of incomplete combustion. It’s colorless, odorless, tasteless, and toxic. In large quantities, it can be combustible.

The products of complete combustion for natural gas are heat, water vapor, and carbon dioxide.

The calorific value of natural gas is 1000 which may vary from location to location. This means 1 ft³ of natural gas gives off 1000 BTUh.

The flame speed for natural gas is 12’’/second.

Natural gas has a boiling point of -260°F and an expansion ratio of 1:600 when boiling from a liquid to vapor.

Propane

Propane has the chemical formula of C3H8 and is a wet gas containing the heavier hydrocarbons. Propane has no color, no taste, no odor (your distributor adds mercaptan for safety which gives a rotten egg smell), is non-toxic (although you may die from insufficient oxygen if there is too much natural gas in the air), and is transparent.

Propane as a vapor has a specific gravity of 1.52. The specific gravity of a gas is the weight of a volume of a gas compared to an equal weight of a volume of air. This means propane as a vapor is heavier than air and during a leak will build up closer to the ground.

Propane as a liquid has a specific gravity of .51, which is less dense than water. The specific gravity of a liquid is the weight of the liquid, propane, compared to the weight of an equal volume of water.

The ignition temperature of propane is lower than natural gas. It takes about 920°F to ignite.

The limits of flammability for propane are 2.4% to 9.5%. So less than 2.4% or over 9.5% of propane in the air will not be enough for combustion to take place.

The products of incomplete combustion are carbon monoxide and aldehydes.

Aldehydes are irritating to the eyes, throat, and nose. They smell terrible. Aldehydes taste somewhat metallic and are likely accompanied by carbon monoxide.

Carbon monoxide (CO) is the most harmful product of incomplete combustion. It’s colorless, odorless, tasteless, and toxic. In large quantities, it can be combustible.

The products of complete combustion are heat, water vapor, and carbon dioxide.

The calorific value of propane is 2500. This means 1 ft³ of propane gives off 2500 Btuh.

The flame speed for propane is 11’’/second.

Propane has a boiling point of -44°F and an expansion ratio of 1:270 when converting from a liquid to vapor.

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