Despite their maturity as a product category, chillers and baths continue their slow evolution, particularly in the areas of controls and user interface.
Cole-Parmer (Vernon Hills, IL) has introduced a new product line that includes immersion circulators, circulating baths, recirculators, and chillers. The immersion circulators (also known as thermal immersion circulators) can maintain a bath temperature from ambient up to 200°F. Cole-Parmer and other vendors provide units with a temperature stability of 0.1°C that use force-only (also called forcegravity) or force-suction pumping.
The pumping mode depends on the application. The force-only mode pumps fluid out and relies on gravity to deliver fluid back to the inlet, whereas force-suction pumps push the bath fluid out and then actively draw it back into the pump. “Force suction provides stronger, more robust pumping,” says Ben Wilbert, product group manager at Cole-Parmer. “Particularly with viscous thermal fluids, or when you are pumping out to an open or closed external loop where you need more pressure or velocity.”
“External loop” refers to an external device or vessel that aids in temperature control. If the fluid flows into an open vessel, the process would be termed “open-loop”. But if the flow line is contained, such as with radiator coolant in a car, then it’s described as a “closed-loop” application.
Controller and data options
Controller options for chillers and baths have multiplied well beyond digital/ analog. Cole-Parmer offers digital controllers with programmable setpoints, high-temperature cutoffs, user-defined limit values, minimum/maximum temperature limits, and adjustable pump nozzles that allow the user to adjust the angle of the flow of the liquid in the bath’s reservoir. This feature can help reduce splashing or excessive agitation, which is significant when the reservoir contains samples.
Advanced controllers offer a greater number of programmable setpoints, greater temperature control, higher circulation capacity, and a USB port for controlling the device from a computer.
Of all vendors, PolyScience (Niles, IL) has perhaps innovated the most on control options and user interface. The company offers four levels of sophistication: the Basic digital controller reaches a maximum temperature of 135°C using a single-speed pump; the Standard digital controller reaches 170°C via a two-speed pump.
Two models in the Performance digital controller line use PolyScience’s SmartTouch™ icon-driven color touchscreen display and controls, which experts agree is the most advanced heating bath interface on the market. Finally, the Performance Programmable digital controller adds unlimited time and temperature programmability to the Performance controller features.
A greater demand for traceability and data logging has given rise to a variety of communication protocols applicable to chillers and baths, for example, Ethernet, USB-A, USB-2, RS242, and RS-485 interfaces. Some can even communicate wirelessly with an iPhone or other handheld device. The PolyScience Performance Programmable controller, for example, exports data via an RS-232 to Microsoft Excel, National Instruments’ LabView™ software, or the PalmOS™ handheld operating system.
Industries or companies requiring top-down documentation, particularly regulated industries, will value these features, particularly as food and drug regulators continue to emphasize safety.
Enter the “chiller/ incubator”
Within the heating and cooling products marketplace, Sheldon Manufacturing (Cornelius, OR) specializes in water baths, including entry-level digital baths, high-temperature baths, and specialty models.
Although the company does not manufacture chillers, it has adapted cooling recirculation technology to one of its CO2 incubator models for customers who wish to operate at or below ambient temperature.
“There isn’t a lot of choice for refrigerated CO2 incubators,” says Mike McLane, sales director.
In a conventional water-heated incubator, the working volume is surrounded by an insulating chamber containing water. In this retrofitted product, coils are inserted into the insulating chamber and circulated to an external chiller that maintains the insulating chamber at a preset temperature.
“Circulating water through an external chiller constantly cools the incubator similar to how coils cool down a refrigerator,” Mr. McLane explains. “But you don’t have the problem of dealing with a compressor.”
Waste not, want not
Ongoing environmental awareness, novel materials of construction, and user-interface upgrades will be key features in the upcoming redesign of chiller equipment at Grant Instruments (Hillsboro, NJ), according to North American sales and marketing manager Joseph Costello. “The industry trend is away from the use of dials and pushbuttons [and toward] touch screens and sealed membrane controls,” he tells Lab Manager Magazine.
Manufacturers have already deployed new materials for chillers and baths, such as clear plastics and composites, while upgrading refrigeration compressors to be more energy-efficient and utilize less environmentallyharmful compressor gases.
“As more eco-friendly gases become available, vendors will want to get them into their equipment as soon as possible,” Mr. Costello says.
Grant is part of a British company and, as such, follows the RoHS (Restriction of the Use of Certain Hazardous Substances in Electrical and Electronic Equipment) directive of 2002. Through this guidance, manufacturers of electrical and electronic equipment are expected to limit or eliminate their use of materials such as lead, cadmium, mercury, hexavalent chromium, polybrominated biphenyl, and polybrominated diphenyl ether flame retardants. The company prevails upon its suppliers as well, even those not subject to RoHS, to comply with the directive. Grant is also at the forefront of recycling equipment that has fulfilled its earthly mission and designing recyclability into its chillers, baths, and other equipment.
Next to advanced controllers, userinterface improvements have been the top technological upgrades in chillers and baths. “Ten years ago, chillers featured LED screens, then LCD displays that held more information,” says Mr. Costello. “Today we have touch screens and membrane- covered controls, smooth surfaces that keep water out.”
But users, Mr. Costello says, are more likely to be swayed to purchase based on the interface rather than advanced controls. The reason is that instruments from reputable manufacturers already provide adequate temperature control and uniformity.