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Bath and Chiller Design Derives from Both Capacity and Utility

Bath and Chiller Design Derives from Both Capacity and Utility

How design features in the latest baths and chillers make life easier in the lab

Brandoch Cook, PhD

Baths

The water bath is both the most ubiquitous, and sadly the most forgotten, piece of research laboratory equipment. If your laboratory space is anything like the suite I’m in, you may even still have the same holdover Precision 183 model from about 1987 backed into a corner, with the crusted asterisk of tape over the temperature dial warning potential meddlers: Do Not Touch. However, its quotidian nature and homely design belie its durability through almost constant use, and may allude to the longevity and parsimony of your principal investigator, who can pass it on when he retires, telling his favorite junior successor, “Here, take this. I’ve had it since before the university computerized its inventory and tagged equipment with bar codes.” While indestructible and inarguably useful, these bellwethers of established laboratories can also be as frustrating as the appendix or the pinky toe. We know they are there for an evolutionary reason, but we don’t notice them until neglect or abuse mark them as glaring and tragic vestiges in an otherwise sleek body.

For example, if you have assigned lab jobs to your personnel, and the water bath designee has forgotten to clean them and apply germicide, chances are high that any contamination you discover in your tissue culture reagents, or sensitive molecular biology experiments, is coming from those baths. Alternatively, if someone walks by and bumps the dial with her elbow, they may inadvertently change the temperature dramatically. Now your enzymes or your thawing vials of precious cells are cooking instead of making their contributions to science, and by the time you notice, it will take a couple of days of tinkering with the dial to get it back to exactly the right place. (Note: always keep an accurate thermometer in any bath, and check it before you put any reagents or samples in there). Conveniently, it turns out that the technology advanced to digital temperature control many years ago. Moreover, the specialized provider Lab Armor began offering bead-based baths around a decade ago, mitigating much of the maintenance and contamination worries associated with water baths. Although retail prices are higher, the cost of replacing a water bath with a bead bath is often less than the cost of lost time and reagents due to one contamination event.

Like water baths, bead baths allow temperature control of reagents and samples from ambient to 100 degrees Celsius. The switch from water to thermal, non-uniform, metallic alloy beads, however, creates an ergonomically favorable situation in which tubes, vials, and flasks can stand upright with openings and cap threads well above the surface of the heating medium, with no potential for seepage into or out of those containers. Bead baths also eliminate the need for liquid germicides, removing potentially powerful environmental and biological pollutants from their inevitable disposal and distribution through the water cycle. The dry medium obviates the risk of splashback hazards when baths are hot, or burn hazards when heated steel reservoirs need to be dumped and refilled. Instead, beads are in principle eternal, with no need to replace or clean them other than an intermittent ethanol spray. Finally, bead baths just somehow look cool and futuristic, even though they have inhabited the present since it was the somewhat-recent past. The near future of the technology may include the introduction of novel alloys that allow compatibility with temperatures greater than boiling, in a way that can compete with the greater scalability and temperature control of circulating baths. Correspondingly, there may be forthcoming changes in bead design to better mimic the heat transfer and bath uniformity properties of water so that the depth and volume of beads have less of an impact on discrepancies between gauge temperatures and measured temperatures.

Chillers

A chiller, in its simplest iteration, removes heat from a liquid via vapor compression or a refrigeration/absorption cycle, and circulates the chilled liquid to cool associated equipment, samples, or another effluent stream. Similar to an air conditioner, its cooling power is measured in BTUs, representing the amount of heat removed over time. Chillers are, of course, more versatile and the scale of cooling needed in the laboratory, medical, or industrial environment is a consideration unique to the experiment being done or to the equipment requiring temperature control. Chillers can be used by any biomedical laboratory to precisely specify a low temperature for a given experiment, such as optimizing DNA ligations at 16 degrees. However, their power and versatility come into better focus as temperature control modules for expensive and sensitive equipment. Such equipment includes electron microscopes and LC-MS apparatuses that exude and would otherwise trap heat in closet-sized rooms, as well as MRI, particle accelerators, and experimental lasers that function optimally within narrow temperature ranges.

Because of this wide variability in chiller applications, calculations to determine power needs are necessary to optimize solutions and obtain the right sizes and configurations. Although these calculations are relatively straightforward, when customizing chiller solutions, you should expect your product rep to be able to accurately complete them for you and develop an appropriate design solution. Therefore, chiller optimization also requires analyzing available space and how chiller configurations fit within that footprint. Additionally, this includes an assessment of whether air-cooled or water-cooled configurations are best, and whether a benchtop chiller is adequate, as they typically provide a maximum of 4000 BTUs (1/3 ton or 1051 Watts). Because air-cooled condensers release heat directly to the surrounding environment, they are generally more suitable for large laboratory spaces—confined equipment rooms therefore will normally necessitate water-cooled condensers. Customization of chillers to associated processes or equipment implies a vast potential for scalability. Accordingly, one configuration can faithfully maintain temperature control of miniscule enzymatic reactions, while another can preserve the function of production equipment in industrial facilities. For example, OptiTemp offers the generalist OTC series of air-cooled and water-cooled chillers, which can be rack-mounted in series or wheeled individually around the research space. At the other extreme, they offer the OTM series of stationary, industrial-capacity chillers, as well as custom solutions to fit both power and space requirements unique to end-user specifications.

The principles of function and the nature of end-user needs have driven the design of both baths and chillers. At opposing ends of temperature control, they offer scaled, precise, and affordable options for laboratory, medical, and industrial capacities.


For additional resources on baths and chillers, including useful articles and a list of manufacturers, visit www.labmanager.com/baths-chillers