2011 Baths and Chillers Survey Results

Water Baths are used in industrial and clinical laboratories, academic facilities, government research laboratories, environmental applications, as well as food technology and wastewater plants. Check out the water bath survey results here.

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By Lab Manager

Water Baths are used in industrial and clinical laboratories, academic facilities, government research laboratories, environmental applications, as well as food technology and wastewater plants. Because water retains heat so well, using water baths was one of the very first means of incubation. Applications include sample thawing, bacteriological examinations, warming reagents, coliform determinations and microbiological assays.

Chillers are refrigerators that cool down samples or processes to preset temperatures by removing heat from one element and transferring it to another, typically air or water. The term “recirculating” refers to the cooling liquid— typically water, water/ glycol, or silicone fluids— that is pumped through the system to be cooled and returned to the chiller. Choice of cooling fluid is critical: The liquid must remain fluid at low temperatures or it will not recirculate; and some good circulators, like ethanol, are highly flammable.

Most general laboratory water baths go from ambient temperatures of +5°C to 99.9°C, with temperature uniformity as tight as ±0.2°C at 37°C. Many vendors offer temperature preset buttons for quick selection of frequently used temperature set points. Chillers operating down to about -40ºC are relatively inexpensive and use a single compressor. The price jumps significantly for the -40ºC to -95ºC temperature range because these systems use two compressors. Units cooling to below -100ºC require three compressors and may cost in excess of $100,000. Some chillers also provide modest heating, to about 40ºC. These units, which may also cool to about -20ºC, are replacements for water cooling systems?

Temperature ranges respondents operate their water baths or chillers.

Less than -100 C 2%
-50 C to -100 C 2%
0 C to -50 C 14%
0 C to +50 C 50%
+50 C to +100 C 30%
More than +100 C 2%

Choosing the right size water bath depends on the volume and size of samples. Water bath sizes can range from 1.5 to 43 liters. To compare different bath volumes, it is best to compare internal tank dimensions. The new waterless bead bath aims to tackle the problem of contamination in water baths by utilizing a dry, metallic thermal media comprised of small beads instead of water.

Different types of water baths may be required, depending on the application. Below is a list of the different types of water baths used by the respondents.

Plan to
Circulating water baths
Standard (general purpose) water baths
Waterless bead baths
Cooled water baths
Shaking water baths
Unstirred water baths
Stirred water baths
Boiling water baths
Steaming water baths

Choosing the right water bath often comes down to economics, yet price is not the only factor. The most important factors in the decision-making process for a new water bath or chiller are performance, low maintenance, greater temperature uniformity, and price. Digital control systems provide greater temperature uniformity, stability and control. Constant temperature digital water baths are suited to a host of applications, including bacteriological examinations, food processing/QC procedures and microbiology assays. Analog systems offer easy-to-use control and are best suited to fixed set-point applications.

If outside contaminants are a concern, it is important to consider a water bath cover. Rounded, seamless, stainless steel reservoir construction resists rust, chemical damage and contamination. An epoxy-powder-coated exterior simplifies cleanup. The exterior also needs to remain cool, to prevent accidental burns even after extended use.

Safety features may include secondary thermostats that automatically disconnect heater power should the bath temperature get too high or the liquid level drop too low, as well as alarm indicators.

In purchasing a chiller, applications should determine the specifications - most laboratory customers have unique applications and need equipment designed specifically for their needs. Vendors suggest that factors to consider include ambient operating temperature, desired process temperature range, temperature control tolerance, process fluid type, process fluid pumping volume, process fluid supply pressure, and most importantly, the amount of heat to be dissipated from the process. Most lab managers will be put off by the calculations required for sizing a chiller. However, if the user knows the general parameters of heat removal required, vendors can perform those calculations. Vendors can also help specify a chiller based on its intended application.

Top twelve factors/features
Performance of product 98%
Low maintenance / easy to clean 95%
Greater temperature uniformity, stability and control 93%
Value for price paid 92%
Low Operating costs 85%
Total cost of ownership 80%
Ease of use; ergonomic operation 79%
Digital temperature control 78%
Warranties 77%
Size of water bath 76%
Covers / lids 73%
Safety and health features 70%

Completed Surveys: 284

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Published In

Go, Go Gadgets Magazine Issue Cover
Go, Go Gadgets

Published: July 5, 2011

Cover Story

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