Construction of a crosswalk using polymer modified cement slurry

A propane torch is a

tool A tool is an Physical object, object that can extend an individual's ability to modify features of the surrounding environment or help them accomplish a particular task. Although many Tool use by animals, animals use simple tools, only human bei ...

normally used for the application of

flame A flame () is the visible, gaseous part of a fire. It is caused by a highly exothermic chemical reaction made in a thin zone. When flames are hot enough to have ionized gaseous components of sufficient density, they are then considered plasm ...

heat In thermodynamics, heat is energy in transfer between a thermodynamic system and its surroundings by such mechanisms as thermal conduction, electromagnetic radiation, and friction, which are microscopic in nature, involving sub-atomic, ato ...

which uses

propane Propane () is a three-carbon chain alkane with the molecular formula . It is a gas at standard temperature and pressure, but becomes liquid when compressed for transportation and storage. A by-product of natural gas processing and petroleum ref ...

, a hydrocarbon

gas Gas is a state of matter that has neither a fixed volume nor a fixed shape and is a compressible fluid. A ''pure gas'' is made up of individual atoms (e.g. a noble gas like neon) or molecules of either a single type of atom ( elements such as ...

, for its

fuel A fuel is any material that can be made to react with other substances so that it releases energy as thermal energy or to be used for work (physics), work. The concept was originally applied solely to those materials capable of releasing chem ...

and ambient air as its combustion medium. Propane is one of a group of by-products of the

natural gas Natural gas (also fossil gas, methane gas, and gas) is a naturally occurring compound of gaseous hydrocarbons, primarily methane (95%), small amounts of higher alkanes, and traces of carbon dioxide and nitrogen, hydrogen sulfide and helium ...

and

petroleum Petroleum, also known as crude oil or simply oil, is a naturally occurring, yellowish-black liquid chemical mixture found in geological formations, consisting mainly of hydrocarbons. The term ''petroleum'' refers both to naturally occurring un ...

industries known as

liquefied petroleum gas Liquefied petroleum gas, also referred to as liquid petroleum gas (LPG or LP gas), is a fuel gas which contains a flammable mixture of hydrocarbon gases, specifically propane, Butane, ''n''-butane and isobutane. It can also contain some ...

(LPG). Propane and other fuel torches are most commonly used in the manufacturing, construction and metal-working industries.

Fuels

Propane is often the fuel of choice because of its low price, ease of storage and availability, hence the name "propane torch". The gasses

MAPP gas MAPP gas was a trademarked name, belonging to The Linde Group, a division of the former global chemical giant Union Carbide, for a fuel gas based on a stabilized mixture of methylacetylene (propyne), propadiene and propane. The name comes from ...

and Map-pro are similar to propane, but burn hotter. They are usually found in a yellow canister, as opposed to propane's blue, black, or green. Alternative fuel gases can be harder to store and more dangerous for the user. For example,

acetylene Acetylene (Chemical nomenclature, systematic name: ethyne) is a chemical compound with the formula and structure . It is a hydrocarbon and the simplest alkyne. This colorless gas is widely used as a fuel and a chemical building block. It is u ...

needs a porous material mixed with acetone in the tank for safety reasons and cannot be used above a certain pressure and withdrawal rate.

Natural gas Natural gas (also fossil gas, methane gas, and gas) is a naturally occurring compound of gaseous hydrocarbons, primarily methane (95%), small amounts of higher alkanes, and traces of carbon dioxide and nitrogen, hydrogen sulfide and helium ...

is a common fuel for household cooking and heating but cannot be stored in liquid form without cryogenic refrigeration.

Mechanism

Small air-only torches normally use the

Venturi effect The Venturi effect is the reduction in fluid pressure that results when a moving fluid speeds up as it flows from one section of a pipe to a smaller section. The Venturi effect is named after its discoverer, the Italian physicist Giovanni Ba ...

to create a pressure differential which causes air to enter the gas stream through precisely sized inlet holes or intakes, similar to how a car's

carburetor A carburetor (also spelled carburettor or carburetter) is a device used by a gasoline internal combustion engine to control and mix air and fuel entering the engine. The primary method of adding fuel to the intake air is through the Ventu ...

works. The fuel and air mix sufficiently, but imperfectly, in the burner's tube before the flame front is reached. The flame also receives some further oxygen from the air surrounding it. Oxygen-fed torches use the high pressure of the stored oxygen to push the oxygen into a common tube with the fuel.

Uses

Propane torches are frequently employed to

solder Solder (; North American English, NA: ) is a fusible alloy, fusible metal alloy used to create a permanent bond between metal workpieces. Solder is melted in order to wet the parts of the joint, where it adheres to and connects the pieces aft ...

copper water pipes. They can also be used for some low temperature

welding Welding is a fabrication (metal), fabrication process that joins materials, usually metals or thermoplastics, primarily by using high temperature to melting, melt the parts together and allow them to cool, causing Fusion welding, fusion. Co ...

applications, as well as for

brazing Brazing is a metal-joining process in which two or more metal items are joined by melting and flowing a filler metal into the joint, with the filler metal having a lower melting point than the adjoining metal. Brazing differs from welding in ...

dissimilar metals together. They can also be used for annealing, for heating metals up in order to bend them more easily, bending glass, and for doing

flame test A flame test is relatively quick test for the presence of some elements in a sample. The technique is archaic and of questionable reliability, but once was a component of qualitative inorganic analysis. The phenomenon is related to pyrotechnics ...

Complete and incomplete combustion

With oxygen/propane torches, the air/fuel ratio can be much lower. The

stoichiometric Stoichiometry () is the relationships between the masses of reactants and products before, during, and following chemical reactions. Stoichiometry is based on the law of conservation of mass; the total mass of reactants must equal the total m ...

equation for complete combustion of propane with 100%

oxygen Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...

is: :C₃H₈ + 5 (O₂) → 4 (H₂O) + 3 (CO₂) In this case, the only products are CO₂ and

water Water is an inorganic compound with the chemical formula . It is a transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance. It is the main constituent of Earth's hydrosphere and the fluids of all known liv ...

. The balanced equation shows to use 1 mole of propane for every 5 moles of oxygen. With air/fuel torches, since air contains about 21% oxygen, a very large ratio of air to fuel must be used to obtain the maximum flame temperature with air. If the propane does not receive enough oxygen, some of the carbon from the propane is left unburned. An example of incomplete combustion that uses 1 mole of propane for every 4 moles of oxygen: :C₃H₈ + 4 (O₂) → 4 (H₂O) + 2 (CO₂) + 1 C The extra carbon product will cause

soot Soot ( ) is a mass of impure carbon particles resulting from the incomplete combustion of hydrocarbons. Soot is considered a hazardous substance with carcinogenic properties. Most broadly, the term includes all the particulate matter produced b ...

to form, and the less oxygen used, the more soot will form. There are other unbalanced ratios where incomplete combustion products such as

carbon monoxide Carbon monoxide (chemical formula CO) is a poisonous, flammable gas that is colorless, odorless, tasteless, and slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the si ...

(CO) are formed, such as: :6 (C₃H₈) + 29 (O₂) → 24 (H₂O) + 16 (CO₂) + 2 CO

Flame temperature

An air-fed torch's maximum

adiabatic flame temperature In the study of combustion, the adiabatic flame temperature is the temperature reached by a flame under ideal conditions. It is an upper bound of the temperature that is reached in actual processes. There are two types of Adiabatic process, adiab ...

is assumed to be around . However, a typical primary flame will only achieve to . Oxygen-fed torches can be much hotter at up to .

References

Bibliography

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External links

How to Silver Solder Steel with a Propane Torch

How To properly Heat Up Copper Pipe Using A Propane Torch
{{DEFAULTSORT:Propane Torch Burners Metalworking tools Welding

Torch A torch is a stick with combustible material at one end which can be used as a light source or to set something on fire. Torches have been used throughout history and are still used in processions, symbolic and religious events, and in juggl ...