Baths and Circulators
What are Laboratory Baths?
A water 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 an analogue interface to allow users to set a desired temperature, but some water baths have their temperature controlled by a current passing through a reader. Utilisations include warming of reagents, melting of substrates 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 prevents ignition. Different types of water baths are used depending on application. For all water baths, it can be used up to 99.9 °C. When temperature is above 100 °C, alternative methods such as oil bath, silicone bath or sand bath may be used.
Application
Water bath is a preferred heat source for heating flammable chemicals instead of an open flame to prevent ignition. The other areas of its utilizations include warming of reagents, melting of substrates, or incubation of cell cultures
Different Types of Laboratory Baths
General Baths: 
This type of water bath relies primarily on convection 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. No refrigeration options. Accessories: Lid, Flask holders, Tube Holders
Circulating water baths
Circulating water baths are ideal for applications when temperature uniformity and consistency are critical, such as enzymatic and serologic experiments. Water is thoroughly circulated throughout the bath resulting in a more uniform temperature. Also have refrigeratrion options. Accessories: Lid, Flask holders, Tube Holders
Shaking Water Baths
This type of water bath has extra control for shaking, which moves liquids around. This shaking feature can be turned on or off. In microbiological practices, constant shaking allows liquid-grown cell 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. Accessories: Spring wire rack, Flask holders.
Recirculators and Chillers
Offer thermostatic control across their temperature range capability. They circulate fluid to demanding closed loop applications with a temperature range of –10 to 80°C that typically require higher flow and pressure requirements with heat loads up to 5000 watts.
Viscosity Baths
Ideal for maintaining constant temperature required for Kinematic Viscosity measurements. Baths meet ASTM D445 requirements.
What is the Working Principle of a Water Bath?
In a laboratory the unit is fitted with a temperature sensor, which works by transferring the water temperature to the resistance value and amplifying and comparing with an integrated amplifier. The output is the control signal which efficiently controls the average heat power for the heating tube. This works to maintain the constant temperature within the water bath.
How Do You Prepare A Water Bath?
To prepare a water bath, you need to fill the container to the desired level with distilled water. You can then switch the water bath on and set your required temperature on the temperature controller. Wait until the water has reached the set temperature; the length of time this takes will depend on the temperature you need the water to be. You can use the thermometer to monitor the water temperature. Once it has reached the temperature, you are ready to start using the water bath.
How Do You Use A Water Bath?
Using a water bath is straightforward, but it is crucial you get it right to avoid damaging or compromising your samples. The basic steps for a hot water bath are:
- Ensure the surrounding area is dry and clean.
- Connect the power supply.
- Make sure the water is at the desired level and high enough to cover the heating element.
- Switch the water bath on.
- Set the temperature controls to the desired temperature and wait until the thermostat shows it has heated enough.
- When heating, insert your samples carefully. The temperature sensor will maintain the temperature during use.
- After use, remove the samples and switch off the water bath.
How to Maintain A Water Bath?
No matter the type of water bath you are using, proper maintenance is essential for a prolonged life. Firstly, you must consider the type of water you are going to be using. Distilled water works best because tap water can contain minerals that build up over time. Secondly, make sure you drain the water bath each time to keep it in good condition. You need to take the time to clean this equipment regularly. To clean a water bath, make sure it is switched off and remove the container. Wipe down the seal to clear any debris and be very careful not to spill water into the unit, as it can damage electrical components. Never use corrosive cleaning agents on a water bath, and only clean with a damp cloth and mild detergent.
Information required to to quote on an Autoclave
- What temperature do you require?
- If heated. Do you require a general bath or a circulated bath? A circulated bath has a better temperature accuracy
- What tank capacity do you require?
- Do you require other accessories? Eg Lid, Flask holder, Viscosity Tube holders etc
- Do you require shaking?
Further Reading
https://www.labcompare.com/10-Featured-Articles/127452-Buyer-s-Guide-to-Water-Baths-and-Chillers/
https://www.weighinginstru.com/how-to-choose-a-suitable-thermostatic-water-bath-201.html