Awater bath is laboratory equipment made from a container filled with heated water. It is used to incubate samples in water at a constant temperature over a long period of time. Most water baths have a digital or ananalogue interface to allow users to set a desired temperature, but some water baths have their temperature controlled by a current passing through a reader.
Uses include warming ofreagents, melting ofsubstrates, determination ofboiling point, or incubation of cell cultures. It is also used to enable certain chemical reactions to occur at high temperature.
Water baths are preferred heat sources for heating flammable chemicals, as their lack of open flame preventsignition.[1] Different types of water baths are used depending on application. For all water baths, it can be used up to 99.9 °C.[2][3]
When the required temperature is above 100 °C, alternative methods such as oil bath,silicone oil bath or sand bath may be used.[4]
It is not recommended to use water bath withmoisture sensitive orpyrophoric reactions.[5] Do not heat a bath fluid above its flash point.[5][6] Water level should be regularly monitored, and filled with distilled water only.[7][8] This is required to prevent salts fromdepositing on the heater.[8]Disinfectants can be added to prevent growth of organisms.[6][7] If application involves liquids that give offfumes, it is recommended to operate water bath in fume hood or in a well ventilated area.[9] The cover is closed to prevent evaporation and to help reaching high temperatures.[9]
Circulating water baths (also calledstirrers[10]) are ideal for applications when temperature uniformity and consistency are critical, such asenzymatic andserologic experiments. Water is thoroughly circulated throughout the bath resulting in a more uniform temperature.
This type of water bath relies primarily onconvection instead of water being uniformly heated. Therefore, it is less accurate in terms of temperature control. In addition, there are add-ons that provide stirring to non-circulating water baths to create more uniform heat transfer.[4]
This type of water bath has extra control for shaking, which moves liquids around. This shaking feature can be turned on or off. Inmicrobiological practices, constant shaking allows liquid-growncell cultures grown to constantly mix with the air.
Some key benefits of shaking water bath are user-friendly operation via keypad, convenient bath drains, adjustable shaking frequencies, bright LED-display, optional lift-up bath cover, power switch integrated in keypad and warning and cut-off protection for low/high temperature.
The bath is a fundamental product in any laboratory. Over the years, water baths have evolved from basic analog tools to advanced digital machines capable of sophisticated and programmable controls, functions, and capabilities.
Key features in water baths often include:
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