Care and Preventive Maintenance for Water Baths and Chillers

Water Baths and Chillers Best Practices

laboratory water bathWater baths and recirculating heaters and chillers a are laboratory staples. Whether heating up samples or cooling them down, at some point, all lab professionals need to use this type of equipment. These units are often shared, which can cause problems like contamination or improper use and upkeep. Adhering to best practices can help ensure correct use and consistent maintenance, thus providing reliable temperature and optimal performance for many years.

Proper unit operation

Operate units with caution. Monitor temperature and water levels daily. To prevent temperature loss, always use the lid. Before following these recommendations, make sure there are no exceptions in the manual provided with your specific equipment.

Cleaning is critical

Today’s water baths and chillers are easy to clean. Water baths and chillers need to be kept clean. Before cleaning equipment, make sure the unit is unplugged from the outlet.

Drain, clean, and refill water-filled baths weekly to avoid buildup of salts and contamination. Regularly adding fresh water will replenish the oxygen, which helps maintain the protective chromium oxide layer on baths manufactured with stainless steel. This is especially important if the water is stationary or has been boiled.

Baths that are used for biological applications and heated to physiological temperatures can create breeding grounds for algae, fungi, and harmful pathogens Regular heating for 30 minutes to the temperature for your specific equipment can be used to thermally disinfect the bath before cleaning. If this is not possible, then a chemical biocide may be used. Check that the agent is suitable for use with the material such as stainless steel. Do not use bleach (sodium hypochlorite) or other chlorine-based solutions as a disinfectant.

Make sure the bath contains sufficient liquid to cover the heating element to avoid running dry.

Turn the bath off overnight or when not in use. If a bath will not be used for some time, it should be emptied, cleaned, and kept dry.

Baths should be cleaned with a very mild household or laboratory detergent using a sponge or soft cloth. Never use scouring powders, steel wool, or other abrasive pads. Metal buildup can be removed using a mild household de-scaler and soft brush. Rinse thoroughly after cleaning and be sure to dry the bath.

Keep contaminants to a minimum

Wipe down and sanitize containers, work benches, and anything that comes in contact with the water. Use and change gloves frequently. Use distilled water in the unit, as tap water may contain bacteria and other particles that could corrode the unit over time. Deionized water should not be used as it can cause corrosion in your bath. Float the sample so the lid stays dry. Use a sample rack to prevent samples from tipping and contaminating the water.

Metallic bath beads can be used instead of water for certain baths, or baths specifically made to be used with beads. The use of beads instead of water avoids splashing, dripping, and the majority of transfer contamination. Beads make it easy to hold a container at almost any angle without damaging the sample. If you use beads that do not collect moisture, it’s easier to keep them clean. Beads need to be cleaned as well.

While these best practices can ensure the longevity and safety of water baths and chillers, always read the manufacturer’s instructions for your particular piece of equipment to make sure you are getting the most out of the equipment in your lab.

What liquid should be used in a recirculating chiller or heater?

Make sure to use distilled water as this is least likely to cause corrosion.

Fifty/fifty water with laboratory-grade ethylene glycol should be used with temperatures below 5 °C. The amount of glycol added should cover a temperature range around 5 °C lower than the operating temperature of the application. This will prevent the water/glycol from gelling (freezing) near the evaporating coil. The maximum recommendation is 50% ethylene glycol. Excess glycol can ruin the temperature accuracy due to its high viscosity. All heat transfer fluids are supplied with a data sheet explaining the usage temperature.

For higher temperatures, outside the water’s range, silicone bath fluid is usually recommended. However, silicone tubing is not compatible with silicone bath fluid. As always, consult the operation manual of your device to make sure you are following safe operating procedure.

Electrical safety

Water baths and recirculating heaters or chillers will protect the user from electrical shock by grounding appropriate metal parts. The protection will not function unless the power cord is undamaged and connected to a properly grounded, dedicated outlet. It is the user's responsibility to maintain a proper ground connection. Please consult your unit’s manual for further details. Also, make sure the cord is accessible at all times, but do not allow cords to hang from counters in a manner that the cords could cause a hazard for someone to trip over and cause the equipment to fall.


Following these best practices—proper operation, consistent cleaning, keeping contaminants at bay, using the correct liquids, and electrical safety awareness—can help mitigate common problems and keep your equipment working at optimal performance over and over again.

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