Need a Dry Bath for your lab?
Laboratory dry baths are scientific equipment that provides users with a temperature-controlled environment, allowing them to incubate samples and perform tests or experiments at a specific temperature.
In terms of design, dry baths are stainless steel chambers with sealed microprocessor controlling units, a digital or analog user interface on the outside front, and (an) aluminum heat block(s) embedded on the chamber top.
The heat block is connected to the heating control unit and contains several conical pockets of various sizes where users can place the samples in fitting containers and incubate them at the desired temperature. Learn more about dry baths (strengths and limitations) here.
Factors to Consider When Choosing a Laboratory Dry Bath
Most contemporary dry baths are digital, possessing a microchip technology that allows users to define a precise temperature point, and monitor the temperature and temperature shift in real-time through a touch screen user interface. The digital elements eliminate the need for an external thermometer, previously required to adjust and monitor analog dry baths.
Modern digital dry baths have various customizable features to suit users’ needs. Here are some things to consider when purchasing a digital dry bath:
1. Multiple Dry Baths or Multiple Heat Blocks?
Dry baths are suitable for various settings. However, laboratories requiring dry baths for one specific routine work may consider dry baths with multiple heat blocks rather than having multiple dry baths.
For example, our two-block dual-chamber digital dry bath has two heat blocks that can be customized to suit the size of the sample containers – it can accommodate many samples incubated at one temperature at a time.
Conversely, research laboratories with multiple users but no shared protocol for dry baths may benefit more from having many dry baths than one with several heat blocks.
2. Fixed or Removable Heat Block?
Another factor to consider is the number and construction of the heat blocks. Laboratories working with specific samples and testing protocols should consider choosing a dry bath with a fixed heat block. Users can determine the most frequently used container sizes and select a fixed heat block with compatible pocket sizes.
On the contrary, laboratories handling various sample types or container sizes can benefit from dry baths with removable heat blocks like the four-block digital dry bath, which has four removable aluminum heat blocks that can accommodate 0.5, 1.5, 2.0, 15, and 50mL conical tubes used in most research, analytical, and clinical settings.
3. Temperature Range
Typical dry baths can create temperatures from 5°C above the ambient temperature up to 105°C to 130°C. Some newer models have cooling features, providing temperatures lower than the room temperature. The choice of the temperature range is based solely on the intended applications.
4. Temperature Fluctuation
Most dry baths create temperatures in 0.1 to 0.3°C increments and have similar ranges of temperature accuracy and uniformity. As a rule of thumb, temperature fluctuation should not exceed ±0.5°C as it can affect the biological and chemical tests.
Nowadays, digital dry baths have a built-in user recalibration function, enabling users to test and reestablish the accuracy of the displayed temperature.
5. Additional Features
Other than heat block and temperature-related features, most digital dry baths also have a timer function. It allows users to set a timer on how long the dry bath should maintain a specific temperature or measure how long the dry bath has been operating at a specific temperature.
Many also have a built-in buzzer or an alarm function to alert users of important events such as reaching the predefined temperature, and failure to regulate fluctuating temperate.
The timer and built-in alarm allow users to set and walk away from the dry bath and come back to it when the work is finished or when the device needs attention.
Shaking dry baths, also known as thermo-shakers or thermo-mixers, are combined shaker incubators and dry baths. The construction is much like dry baths but with an additional oscillating chamber. Samples packed in heat block pockets of shaking dry baths can be swirled and mixed as if they are being incubated in a shaker incubator.
In addition to functional elements, accessory elements make dry baths easier to use. Examples include insulated handles, block lifters, and a removable transparent hinged lid. The handles and block lifters allow users to change the heat blocks when hot, while the removable lid creates a layer of air above the heat block to reduce temperature stratification and bolster temperature uniformity.
Dry Baths, Water Baths, or Lab Incubators?
Dry baths are functionally similar to laboratory incubators and water baths. However, lab incubators and water baths are different from dry baths because they are more universal.
Both lab incubators and water baths can accommodate any number and size of samples, given that they can fit the inside of the chamber. In dry baths, the number and size of samples are limited to the number and shape of the pockets in the heat block.
From a practical perspective, water baths are functionally more similar to dry baths. Both water and dry baths possess a stainless steel body containing microprocessor-controlling units and a digital or analog user interface.
Like dry baths, the temperature in water baths is uniform. This is because it is used to transduce thermal energy in water baths, so they do not suffer from having cold spots in some areas like the lab incubator chamber.
Dry Baths or Water Baths? What’s the Difference?
In general, dry baths can substitute water baths in applications that require heat to be transferred to samples. Nonetheless, both have certain benefits and drawbacks, and the following points should be taken into consideration when deciding between the two:
1. Temperature Range
In water baths, water, instead of air, transfers thermal energy from the source to samples. Thus, typical water baths can accommodate temperatures above the ambient temperature up to 99.9°C. Dry baths are more suitable if the desired temperatures are above or below this range.
2. Temperature Sensitivity
Since water has a higher heat capacity, it can act as an insulator and retain the desired temperature longer than air. Once the water in the water bath reaches the pre-defined temperature, samples are heated faster, and the sample temperature is less fluctuated.
Therefore, water baths are more suitable for temperature-sensitive applications such as enzymatic and serology tests and for incubating large sample volumes.
Nonetheless, having a high heat capacity also means that water baths consume higher energy and take a longer time than dry baths to reach the chosen temperature.
3. Chemical Compatibility and Risk of Ignition
The chemical properties of the samples are also essential when deciding between water and dry baths. Flammable liquid is a case in point for choosing water baths over dry baths.
If sample containers break, the flammable liquid can be mixed with water, diluting the chemical and reducing the risk of ignition. By the same token, dry baths are more suitable for water-incompatible chemicals such as alkaline metals.
4. Risks of Sample Contamination
Most of the water bath volume is filled with water mixed with preservatives. For this reason, they are generally more prone to microbial contamination and require more effort to decontaminate and keep them clean. Thus, dry baths are preferable for sterile or contagious samples due to the ease of sterilization and cleaning.
5. Container Size or Sample Volume
One major limitation of dry baths is that the size or volume of the sample container is restricted by the size and number of the heating block pockets. For this reason, dry baths can only hold standard-sized containers such as test tubes and vials.
Dry baths offer users a means to conduct biochemical tests at a predefined temperature. However, testing samples must be in standard-sized tubes or vials that fit the pocket of the heat blocks.
Modern digital dry baths possess several customizable features such as interchangeable heat blocks, built-in recalibration, and alarm functions, which enhance their functionality and provide convenience for users.
Check out our dual-chamber digital dry bath if you need a high-end dry bath that offers you several customizable features.
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- Johns, W.L. and El-Nageh, M.M. (2000). Selection of basic laboratory equipment for laboratories with limited resources., WHO Regional Publications, Eastern Mediterranean Series 17, World Health Organization.