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Choosing a CO2 Incubator

July 25, 2016

To a certain extent, choosing a CO2 incubator is largely a personal preference on the part of the researcher. Whether Air jacketed or water jacketed, CO2 incubators remain an integral part of many labs.

Water Jacket CO2 Incubators
A traditional CO2 Incubator uses a water jacket to help stabilize temperature, a HEPA filter to help remove contaminates, and a fan for circulating air. The circulating air helps stabilize temperature and draw air across the HEPA filter. The chamber is surrounded by walls filled with hot water. Due to the fact that water holds heat longer than air, the water jacket incubator will hold temperature longer than an air jacketed incubator in the event of a power failure. The temperature uniformity overall can be better in an water jacketed, however due to recent improvements in air circulation, some air jacketed incubators are also devoid of any “cool spots” , There are a few downsides to water jacketed incubators—they take longer for the initial set up (since it takes a while to fill the jacket with water and get the water up to temperature for the first use) and they are also heavier, so more cumbersome to move. In fact, MUST drain the water before moving the unit. In addition, even though sterile distilled water is often used in the water jacket, bacterial and fungal growth can still occur. When this happens, the water jacket itself could become a source of cell culture contamination—a fact that has deterred many from water jacketed incubators. Water-jacked incubators at one time were the most popular option. However, due to improvements in temperature uniformity in air jacketed and a lower threat of contamination, air jacketed have become more and more popular.

Forced air CO2 incubator
Air jacketed incubators, also known as Forced Air CO2 Incubators are easy to set up and reach temperature quickly. A popular option for air jacketed incubators is high heat sterilization. With this option, units reach upwards of 180° C effectively sterilizing the unit and greatly decreasing the threat of contamination. The high heat sterilization is not an option on water jacketed incubators due to the extended time for the water to cool down from such extreme temperatures. The one downside to the forced-air air jacketed incubator is that in the event of a power outage, it will cool more rapidly than a water jacketed. The cooler temperatures could have a detrimental effect on cell growth if left without power for a prolonged period of time. Because of this reason, many labs will purchase a back-up power option or generator. As stated earlier, air jacketed incubators have made significant strides in the last 10 years, allowing for better temperature uniformity and less “cool spots”. It is important for a lab to inquire about the air flow within an air jacketed incubator. Normal maintenance and checkup on the incubator will ensure better temperature uniformity. A cracked or worn out door gasket is one of the main causes of temperature inconsistency. Gaskets should be inspected at least monthly and replaced every year or so (depending on use and how many times the door is opened).

More Information
Another decision that needs to be made in choosing an incubator is what type of CO2 controller to choose TC (thermal conductivity) controls are no longer common as they do not precisely monitor the CO2 levels. IR (infrared) on the other hand, offer. a much tighter control, less variability, and allows the incubator to recalibrate its CO2 more quickly as it does not depend on temperature & humidity. An IR sensor is unaffected by changes in temperature and humidity and is the ideal choice for situations where the incubator door is opened frequently.

Last step
Once a researcher has chosen what type of incubator best suits his or her lab, the next big decision is where to place it. Incubators should not be placed in direct sunlight, near heat sources (i.e. ovens or autoclaves) or near fast moving air currents, such as heating/cooling ducts or near a door. To optimize air circulation around the unit, the incubator should have a minimum of 4 inches of space between a wall or partition on all sides, as anything closer could obstruct airflow. All units come with leveling feet to insure that the unit sits level and solid on the floor (or on top of another unit, in the case of stacked incubators).

To increase longevity of the lab’s CO2 incubator, it is important to clean and decontaminate regularly. As discussed earlier, a forced air incubator can ‘self-decontaminate’ by turning the heat to 180 ° C. For a water-jacketed incubator, remove all parts, wash with soap and water, and disinfect with 70% alcohol solution. The shelves can also be autoclaved to ensure full sterilization. Never use a chlorine based bleach or abrasive cleaner as these will damage the stainless steel finish. For all units, it is recommended that the HEPA and CO2 filters, along with the door gasket, be replaced once a year to ensure optimal functionality of the incubator. Questions? Please contact our product manager, Elise Ambrose at This email address is being protected from spambots. You need JavaScript enabled to view it..

MIDSCI Offers both Water Jacketed and High Heat Sterilization CO2 Incubators! Below is a small sampling of our offerings. Contact us to learn more about our full cell culture offerings!