Health care facilities use ultra-low temperature freezers to store large quantities of high-value samples such as genomic material, cell lysates, tissue homogenates, or vaccines that need to be maintained at temperatures of -80oC or lower. These freezers can protect the integrity of samples for months, or even years—provided they maintain regular, stable temperatures.
Because this inventory is often irreplaceable—or extremely costly—the contents of the freezer far surpass the cost of the equipment itself. But, as with any other equipment in a medical or research facility, an unexpected power outage can result in damage to samples stored in the freezer due to temperature excursions.
Because of this the industry is rapidly shifting towards a two-pronged approach to maintaining temperature uniformity inside ULT freezers by getting both:
To prevent a potentially disastrous loss of inventory, we have detailed the steps you can take and equipment you can have professionally installed to modernize your facility’s medical cold storage program.
A CO2 backup system is a backup kit that supplies a pathway into an ultralow temperature freezer unit. It relies on liquid gases to maintain the low temperatures of samples stored in the freezer. Another system that works like this is an LN2 backup system. The systems have a backup module that controls the addition of coolant to the freezer chamber when the temperature rises above a preset threshold.
A CO2 backup system differs from its LN2 counterpart in that while liquid CO2 can maintain temperatures in the region of -55oC to -70oC and lasts for months, LN2 can drop temperatures to about -85oC, but it depletes faster over time and requires constant monitoring.
Equipping your ultra-low temperature freezer with a battery backup system ensures that the freezer retains power during a power outage. By ensuring continuous power to a ULT system you guarantee that:
While in normal times the utility company powers the freezer, its backup power system stays in standby mode, continually charging its batteries while passing energy through to the appliance. However, when an outage occurs, the system automatically detects the drop in voltage begins powering the freezer's electronics (including the alarm system) and compressor.
Once power is restored, the battery system will once again automatically detect the change in voltage and return to standby mode—allowing the appliance to run on building power while the backup system begins to recharge itself for the next time it is needed.
Another benefit you enjoy when you connect your freezer to a backup power system is the provision of surge suppression. The surge suppression feature protects the freezer from sudden power spikes that could damage the freezer’s compressor. They are especially valuable for facilities found in regions where the power supply is known to fluctuate, such as areas prone to hurricanes.
Because ULT freezers need to maintain their temperatures constantly, they have extremely high duty cycles. The duty cycle of an appliance is the amount of time (expressed as a percentage) that it is actively drawing power from its source in significant amounts.
A typical medical refrigerator will run on a 35% duty cycle. That means its drawing energy 35% of the time it is on to power the compressors which produce the cold air. By contrast 65% of the time, it draws little power. Because of this Refrigerators can get by for a long time with a surprisingly small backup power system due to their high efficiency and the lower overall refrigerator temperature.
Naturally, because a typical upright freezers and ultra-low freezers produce much colder air then a refrigerator and run at a lower freezer temperature, they need more power. A typical freezer has a duty cycle of 65%. So almost 2/3s of the time its on it actively needs energy to maintain its temperature. For ULTs total duty cycle usage often reaches 85-90%.
Because of their much higher energy needs, a ULT freezer can expect to need a backup power system that, at a minimum, will be larger in size than the appliance itself. But just because it has a higher duty cycle does not mean that a backup power solution is an inefficient or poor choice.
On the contrary, the primary goal of a backup power solution is not to ensure the protection of the appliance, but the contents inside (which cost more than the freezer or backup system in many cases). So, even if a slightly larger system is required, the investment is well worth it.
Especially as (according to the US EIA) the average power customer has seen their outage time double in the last 10 years due to increased frequency of major weather events.
The most comprehensive and integrated approach for protection against the effects of power outages on your ultra-low freezers would be combining a battery backup system with a CO2 backup system, as this guarantees you added peace of mind, especially on long weekends away from the facility.