Water baths are used to hold lab specimens or reagents at desired temperatures. The relatively high heat retention of water allows it to maintain its temperature. The applications of water baths span a wide range and include coliform determination, immunohistochemistry and microbiological assays. Some of these applications, such as biochemical experiments, require high temperature precision and uniformity in water temperature because temperature can affect reaction rates and efficacy.

Circulating water baths are able to provide temperature uniformity. The circulating units are either integrated into the construction of the baths or purchased as external add-ons. Unlike their simpler counterparts, many water baths with integrated circulation units are capable of both cooling and heating the water. Typically, the units operate between -25 °C and 150 °C. A high-end unit can achieve temperature stability as precise as ±0.005 °C with a digital temperature controller. In addition to this ability, an integrated circulator can be designed to distribute water flow around the perimeter of a water bath to avoid unwanted agitation of samples.

External circulators can be used to improve control over the temperature uniformity of basic water baths and are available as immersion or standalone units. Immersion circulators are placed directly into water, while standalone units are external pumps that require tubing to be connected to a water bath. Immersion circulators are typically heating systems, while standalone units can be for heating or cooling. External circulators do not control temperature as precisely as integrated circulators can—high-end immersion units top out at ±0.015 °C temperature stability.

The features of circulating water baths have been updated as demand for improved automation and user-friendliness has increased. They are commonly available with large digital temperature readouts, and some have glass chambers, allowing end-users to visually inspect their samples during heating or cooling. Wireless controls are also an option, with Thermo Fisher Scientific going as far as to develop a mobile-phone companion application for their VersaCool circulating bath (see IBO 8/15/14). Advanced temperature controllers often include additional software functionality. For example, among other functions, PolyScience’s Performance Programmable controller offers automatic performance optimizations, event scheduling, and temperature trend collection and viewing.

Thermo holds the largest share of the market for circulating water baths, with many brands consolidated under its name. Lauda and Julabo follow, each with product lines that focus on temperature control. Other vendors include PolyScience and Boekel Scientific. The total market demand for circulating water baths was estimated to be just under one hundred million dollars in 2014.

Circulating Water Baths at a Glance:

Leading Suppliers

• Thermo Fisher Scientific

• Lauda

• Julabo

Largest Markets

• Biotechnology

• Pharmaceuticals

• Academia

Instrument Cost

• $500–$9,000