An oil bath is a type of heated bath used in a

laboratory A laboratory (; ; colloquially lab) is a facility that provides controlled conditions in which scientific or technological research, experiments, and measurement may be performed. Laboratories are found in a variety of settings such as schools ...

, most commonly used to heat up chemical reactions. It is a container of

oil An oil is any nonpolar chemical substance that is composed primarily of hydrocarbons and is hydrophobic (does not mix with water) and lipophilic (mixes with other oils). Oils are usually flammable and surface active. Most oils are unsaturate ...

that is heated by a

hot plate A hot plate or hotplate is a heated flat surface on a stove or electric cooker on which food may be cooked, either built into an electric cooker or kitchen stove, or portable, plugged into an electric outlet. Hot plates can also be used as a h ...

or (in rare cases) a

Bunsen burner A Bunsen burner, named after Robert Bunsen, is a kind of ambient air gas burner used as laboratory equipment; it produces a single open gas flame, and is used for heating, sterilization, and combustion. The gas can be natural gas (which is main ...

Use

These baths are commonly used to heat

reaction Reaction may refer to a process or to a response to an action, event, or exposure. Physics and chemistry *Chemical reaction *Nuclear reaction *Reaction (physics), as defined by Newton's third law * Chain reaction (disambiguation) Biology and ...

mixtures more evenly than would be possible with a hot plate alone, as the entire outside of the reaction flask is heated. Generally,

silicone oil A silicone oil is any liquid polymerized siloxane with organic side chains. The most important member is polydimethylsiloxane. These polymers are of commercial interest because of their relatively high thermal stability and their lubricating prop ...

is used in modern oil baths, although

mineral oil Mineral oil is any of various colorless, odorless, light mixtures of higher alkanes from a mineral source, particularly a distillate of petroleum, as distinct from usually edible vegetable oils. The name 'mineral oil' by itself is imprecise, ...

cottonseed oil Cottonseed oil is cooking oil from the seeds of cotton plants of various species, mainly ''Gossypium hirsutum'' and ''Gossypium herbaceum'', that are grown for cotton fiber, animal feed, and oil. cottonseed, Cotton seed has a similar structure to ...

and even

phosphoric acid Phosphoric acid (orthophosphoric acid, monophosphoric acid or phosphoric(V) acid) is a colorless, odorless phosphorus-containing solid, and inorganic compound with the chemical formula . It is commonly encountered as an 85% aqueous solution, ...

have been used in the past.

Hazards

Overheating the oil bath can result in a fire hazard, especially if mineral oil is being used. Generally, the maximum safe operating temperature of a mineral oil bath is approximately , the oil's flash point. Mineral oil cannot be used above due to the compound's boiling point. If higher temperatures are needed, a silicone oil or a

sand bath A sand bath is a common piece of laboratory equipment made from a container filled with heated sand. It is used to evenly heat another container, most often during a chemical reaction. A sand bath is most commonly used in conjunction with a ho ...

may be used instead. Silicone oil baths are effective in the 25 °C (77 °F) - 230 °C (446 °F) range. Sand baths are effective from 25 °C (77 °F) to above 500 °C (932 °F).

In mechanics

Another use of an oil bath is to filter

particulate Particulate matter (PM) or particulates are microscopic particles of solid or liquid matter suspended in the air. An ''aerosol'' is a mixture of particulates and air, as opposed to the particulate matter alone, though it is sometimes define ...

s out of air, by leading the air stream through an unheated oil bath. This type of

air filter A particulate air filter is a device composed of fibrous, or porous materials which removes particulates such as smoke, dust, pollen, mold, viruses and bacteria from the air. Filters containing an adsorbent or catalyst such as charcoal (carbo ...

was used in car and tractor engines, but has been replaced by modern paper air filters; some

small engine A small engine is the general term for a wide range of small-displacement, low-powered internal combustion engines used to power lawn mowers, generators, concrete mixers and many other machines that require independent power sources. These engin ...

s continue to use this system. In some cases oil baths are used to heat bearings so they expand before installing them on shafts of aircraft engines and tractors.

References

Laboratory equipment Filters Particulate control {{chemistry-stub

Use

Hazards

In mechanics

See also

References