As mentioned in our posts “Six Steps to Better Circulating” and “Five Steps to Better Chilling,” the fluid selected for your water baths, circulators, and chillers is very important as it can either enhance or reduce performance. Even further, in some cases, the wrong fluid can cause harm to the equipment.
Here are some things to keep in mind when selecting a fluid:
- Chemical compatibility with the wetted parts of the equipment through which the fluid will circulate. The wetted parts are usually listed in the manual for the equipment.
- Viscosity at your desired temperature. The equipment manufacturer will provide minimum and/or maximum viscosity for their equipment.
- Boiling point and
- Flash point for fluids to be used at high temperatures.
- Freezing point for fluids to be used at low temperatures.
- Safety considerations like fume potential, protective and other special equipment required for use.
- Storage and disposal.
Additionally, remember to review the Material Safety Data Sheet for the fluid before using it. Keep the MSDS near where the fluid is being used and be sure everyone using the equipment is educated on the fluids and knows the location of the MSDS.
Here are some common fluids:
Algaecide: This kills algae. Algae grows in warm, wet areas. It grows in both light and dark (think about lighted fish tanks and the dark corners of ponds for the two extremes). Therefore, the equipment in your lab that has fluid and heat should also have algaecide. You can put it in right from the beginning as preventive maintenance or you can start using it when you see the first signs of algae.
PolyScience polyclean ALGAECIDE is EPA approved.
Bath Cleaner: Now that you are keeping your equipment algae-free (see algaecide above), you want something to keep it clean, too. You can use a bath cleaner diluted into your fluid to run through the system to remove oxidation, mineral, and other deposits that accumulate during daily use. You can start use at any time and then establish a maintenance schedule to meet your needs. Once a month might be a good starting point.
PolyScience’s polyclean BATH CLEANER is citrus based.
Circulating Fluids – Heating:
Silicon oils are ideal for high temperature use. Silicon oil doesn’t evaporate and maintains its thermal properties over long use.
Mineral oil is also well-suited for high temperature use. While it is significantly less expensive than silicon oils, mineral oil will break down quicker and will need to be replaced more often.
PolyScience polytherm fluids include the high-end temperature in the name to make selection easy.
Circulating Fluids – Cooling:
When working with refrigerated and other cooling equipment, it is important to use a fluid that will not freeze because the temperature inside the cooling equipment may be significantly colder than the set temperature.
Water-based synthetic fluids are popular choices for cooling. They can be used across a broad temperature range, especially when used in sealed or vacuum systems.
Glycols, when mixed with water, become antifreeze. This does not mean that you can buy and use automotive antifreeze. What’s good for your car is not necessarily good for your lab equipment.
There are two glycols which are commonly used: Ethylene glycol (EG) and propylene glycol (PG). Of the two, EG has slightly better thermal properties and can cool in a broader temperature range. However, it is highly toxic and not usable in all applications. In those cases, PG is a good alternative. We recommend mixing with distilled water; the best mix rate is 50/50.
PolyScience polycool fluids include the low-end temperature in the name to make selection easy.
Circulating Fluids – Mixes:
Mixes are offered as a convenience and are made up of one or more of the fluids, described above, like a mix of ethylene glycol, water, and algaecide. They are usually sold in volumes that make sense for filling common-sized equipment like chillers.
PolyScience polycool MIX -25 is an antifreeze mix of ethylene glycol, distilled water, and algaecide. It can be used when you need antifreeze for your equipment and application.
PolyScience polyclear MIX 30 is a mix of distilled water and algaecide and can be used in heating applications, and other equipment as directed by the manufacturer.