An oil bath is a thermostatic equipment used in chemical research laboratories to transfer heat indirectly, by thermal convection, to a sample that requires analysis. Thanks to these equipments, the heat transfer is carried out in a uniform way to the sample.
They are generally equipped with stainless steel trays and covered on the inside by an antibacterial layer, this bath allows controlled temperature management and total uniformity thanks to its pump.
How do oil baths work?
Oil baths are essentially the same as water baths with the difference that some oil is used instead of water. They are suitable when the temperatures to be reached exceed 100 ° C. For these baths it is important to use very thick-walled beakers to contain the oil.
Because oils have a high heat capacity and heat slowly, it may be helpful to partially heat the bath oil while the experiment is being set up.
What kinds of oils do these laboratory equipments use?
Ordinary mineral oil should not be used for baths in which the temperature exceeds 200 ° C, above that temperature the bath may self-ignite and the combustion of hot oil is not easily extinguished. If the oil begins to smoke, it is because it is very close to spontaneous ignition and heating must be discontinued immediately.
Water should never fall into the hot oil, this will cause splashes that cause serious burns. Never use an oil in which the presence of water is obvious and keep in mind that the life of the oil in the bath is limited, when it begins to turn dark it is better to discard it because in these conditions the auto-ignition point lowers.
In addition to ordinary mineral oil, there are other oils that are used for baths, including silicone oils, polyethylene glycol in various degrees of polymerization, certain waxes or paraffins, and even edible oil. High molecular weight polyethylene glycols as well as waxes and paraffins are solid at room temperature and this can be an advantage in spill-free handling as well as storage.