Despite their maturity as a product category, chillers and baths continue their slow evolution, particularly in terms of controls and user interface.
Cole-Parmer (Vernon Hills, IL) and other vendors provide units with a temperature stability of 0.1°C that use force-only (also called force gravity) 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 options for chillers and baths have multiplied well beyond digital/ analog. Advanced controllers offer a greater number of programmable setpoints, greater temperature control, higher circulation capacity, touchscreen options, and a USB port for controlling the device from a computer.
A greater demand for traceability and data logging has given rise to a variety of communication protocols applicable to chillers and baths – Ethernet, USB-A, USB-2, RS242, and RS-485 interfaces. Some can even communicate wirelessly with an iPhone or other handheld device.
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.
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,” says Mike McLane, Sheldon sales director. “But you don’t have the problem of dealing with a compressor.”
Manufacturers have also already deployed new materials for chillers and baths, such as clear plastics and composites, while upgrading refrigeration compressors to be more energyefficient and utilize less environmentally harmful compressor gases.
Next to advanced controllers, user interface 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 Joseph Costello, Grant Instruments (Hillsboro, NJ) North American sales and marketing manager. “Today we have touch screens and membrane- covered controls, smooth surfaces that keep water out.”
But users, Mr. Costello says, are more likely to purchase based on the interface rather than advanced controls because instruments from reputable manufacturers already provide adequate temperature control and uniformity.
RCB20-PLUS Refrigerated/Heated Circulation Bath
- Temperature control ranges from -10°C to +100°C and regulated to ±0.03°C
- 12 L per minute circulation pump rate
- Outfitted with a low liquid volume sensor to prevent damage to unit
- Compressor uses R134A refrigerant and includes a sensor that identifies irregular temperatures
LS Series Benchtop Chillers
- Optimized for high performance at low temperatures
- Capable of cooling multiple rotary evaporators
- Features WhisperCool environmental control system
- Includes large, easy-to-read LED display
- Space-saving design
- Temperature stability of ±0.2 or ±0.02 °C
- Adjustable shaking frequency 20 to 200 rpm
- Many accessories including lids, flask & rack holders
- Dry-running safety protection
- Removable shaking insert
EchoTherm™ RIC20 Series Chilling/ Heating Dry Bath
- Settable from -20.0ºC TO 110.0ºC
- Allows the user to run their complex temperature/time profiles by leaving the computer attached to the RIC20
- Takes up as little bench space as possible with the units measuring 6.5” (165 mm) long by 4.75” (120 mm) wide by 3.5” (89 mm) tall without a sample block.
Torrey Pines Scientific