Dry Heating Blocks and Their Use in Laboratories

Dry heat blocks are amongst the most important apparatus in laboratories. They are used to heat delicate samples offering wide temperature ranges and are adaptable to different tube or flask sizes. Dry heat blocks are advantageous because they provide a more hygienic heating environment. 

Various laboratories including molecular biology, clinical, histology, genetic, biochemistry, and environmental laboratories extensively utilize dry heat blocks.

Introduction

Scientific researches include numerous complex steps that require precision. Every laboratory needs different pieces of equipment to help delicate procedures on the way to discoveries, scientific or technological developments. Some of these procedures are specific to a certain research area while some of them are almost universal in all laboratories. One of the most frequently used procedures in laboratories is heating/cooling processes. The temperature change can cause chemical changes, encourage biological growth, or change the physical properties of a material. Consequently, heating types of equipment are amongst the key pieces in a laboratory. 

Properties of Dry Heat Blocks

There is a plateau of heating equipment ranging from basic stove-like apparatus to much more sophisticated ones. Among these, dry heating blocks are used to heat delicate samples in flasks, tubes, and vials. Dry heating blocks, also known as dry baths or dry bath incubators, consist of a stainless steel chamber and aluminum heating blocks. The commercial dry heating blocks are separated into two categories: digital and analog. Digital dry heating blocks incorporate a microchip and a digital interface to the conventional stainless steel chamber and aluminum blocks. Before the introduction of digital dry heating blocks, laboratories and research centers had extensively relied on analog dry heating blocks. Even though analog dry baths provided rapid and even heating of the samples, the temperature control was problematic. The temperature of the blocks was controlled by incremental knobs that the user could turn to change the temperature. Furthermore, monitoring the temperature of the samples required the use of external thermometers. The digital features offer easier temperature selection and display however, they don’t necessarily offer precision since only the temperature of heating blocks can be tracked. In order to obtain, precise temperature control a temperature probe or external thermometer must be used to monitor the temperature of the samples. Dry heating blocks do not take up a lot of space, are lightweight, and can be accommodated directly on the benchtop or any flat surface where testing is performed. The capacity of dry heat blocks is determined by the number of blocks. Depending on the size of the block, a specific number of tubes can be fit into each block. Typically, the block sizes are categorized as 1, 2, and 4 block models. Furthermore, different sizes of tubes ranging from 0.2 to 50 ml can be placed in the blocks. The temperature accuracy/uniformity of the dry bath equipment is usually ± 0.3ᵒC. The digital dry heat blocks also incorporate a timer function to help streamline the heating or cooling processes. Often, dry heat blocks are compared with wet heat blocks that use liquids such as water or oil as the heating media. It is important to establish the differences between these types of heating equipment and utilize them accordingly. In wet heating blocks, tubes, or any specimen to be heated are immersed in the liquid set to a specific temperature. These types of heating equipment are commonly used for routine laboratory applications such as warming reagents, melting substrates, or incubation. Additionally, wet heating blocks are preferred for heating flammable chemicals since the risk of ignition is lower. The biggest drawbacks of wet heating blocks include long heating times to reach the required temperature and lower maximum temperature limits. The wet heating blocks can only heat up to 99.9°C. This limit might be exceeded by using oil as the heating medium however, oil is harder to clean and impractical. On the other hand, dry heat blocks provide rapid and even heating. The temperature range of dry heating blocks is often around 5°C-150°C. Some modern dry heating blocks combine heating and cooling features at the same time and provide negative temperatures. Dry heat blocks are ideal to create sanitary conditions where contamination can be a great problem. Furthermore, since most of the pieces are removable dry heat blocks provide versatility, convenient replacement, cleaning, and disinfection. Dry heat blocks also consume less power than wet heating blocks and are generally smaller in size than wet heating blocks. Heating up dry heat blocks generally only takes 15 to 30 minutes. An important drawback of dry heating blocks is the temperature fluctuations since metals cannot store heat as good as liquids. Hence, dry heating blocks not be able to provide different temperatures at the same time. The fast and even heating features and the superior hygiene of the dry heat blocks make them a fundamental part of laboratories carrying our various studies.

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When to Use Dry Heat Blocks?

Dry heating blocks are extensively utilized in laboratories for precise heating and cooling applications. They are frequently used in molecular biology, clinical, histology, genetic, biochemistry, and environmental laboratories. Additionally, the development of sensitive industrial products also often requires the use of dry heating blocks.

Several different biology and molecular biology processes in which dry heat blocks hold an important place include incubation and activation of cultures, coagulation studies, inactivation of Sera, chain reactions, incubation of enzyme reactions, restriction digests, incubating DNA samples, thermal cycling in hot-start PCR, assay preparation, tissue and cell culture, cross-matching, denaturing DNA, BUN, and antibody IDs. The cooling feature of dry baths is utilized for molecular biology samples that require near freezing medium. Due to their excellent performance in these studies dry heat blocks have also become an important part of vaccine development studies.

The clinical laboratories working with samples such as blood, urine, etc. also widely utilize dry heat blocks. The controlled temperature provides suitable conditions for the preservation of the samples and holds an important place in the execution of in-vitro diagnostics. The dry heat blocks are also utilized in the screening tests of donated blood.

Other important uses of dry heat blocks include residue tests for emulsions such as milk, environmental residues, etc. coagulation studies, hematology, and so on.

Conclusion

Dry heat blocks are laboratory equipment used to heat or cool the samples in a controlled manner. The earlier versions of dry heat blocks were analog heat blocks which included a stainless steel chamber and aluminum blocks. Even though analog dry heat blocks are still used in some laboratories, the technology has moved on to digital dry heat blocks. Digital versions incorporate a microchip and a digital interface to the conventional dry heat blocks. The advantages of digital heat blocks are easy temperature selection and monitoring, and the option of setting a time limit on the heating operation. Digital heat blocks are also smaller, lighter, and safer. However, since only the temperature of blocks can be traced digitally, the inclusion of a temperature probe is necessary to track the temperature of the samples. The most important advantages of dry heat blocks over other types of heating apparatus are rapid and even heating, less power consumption, versatility, and ability to create sanitary conditions since each part can be removed and cleaned separately. However, dry heat blocks can cause temperature fluctuations. Hence, they are not suitable for heating different samples to different temperatures. Dry heat blocks can also cater to different sized tubes, vials, and flasks.

These types of heating apparatus are widely used in laboratories focused on different studies including molecular biology, clinical, histology, genetic, biochemistry, and environmental. In molecular biology and biology labs, dry heat blocks are used for incubation, assay preparation, enzyme or chain reactions, and denaturation. Dry heat blocks also hold an important place in vaccine development studies. Clinical labs utilize dry heat blocks for sample preservation and diagnostics. Laboratories working on environmental studies use dry heat blocks for tests on environmental residues and coagulation studies. These are just some examples of the uses of dry heat blocks in laboratories. But surely there is still a lot more to add to this list since dry heat blocks have proved useful in most sensitive heating or cooling processes.

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References

1.Innovative Dry baths for constant heating of diverse range of tubes. (2019, August 27). Retrieved October 11, 2020, from https://conductscience.com/specimen-lab/benchtop-equipment/dry-baths/

2.Systems, B., 2020. Water Bath Or Heat Blocks (Dry Bath) - What Wins? | BT Labs. [online] Blog.btlabsystems.com. Available at: <https://blog.btlabsystems.com/blog/heat-block-or-waterbath> [Accessed 11 October 2020].

3.The Laboratory People. 2020. Dry Heat Blocks - The Facts - The Laboratory People. [online] Available at: <https://camblab.info/dry-heat-blocks-the-facts/> [Accessed 11 October 2020].

4.Systems, B., 2020. When To Use A Heat Block. [online] Blog.btlabsystems.com. Available at: <https://blog.btlabsystems.com/blog/when-to-use-a-heat-block> [Accessed 12 October 2020].