Ultra-low temperature (ULT) freezers are used within many labs to ensure the safety of valuable samples. ULT freezers come in a range of options that operate between -86°C and -45°C, but most ULTs create a consistent environment where the internal temperature of the freezer remains between -70°C and -80°C.
ULT freezers are used to protect high value sample collections, with some sample collections inside freezers being worth hundreds of thousands of dollars. While there are many factors that govern the usable lifetime of an ULT freezer, most last for around 12-15 years, so they don’t last forever. It’s not just age that can be a factor for freezer replacement. There are now many more energy efficient options on the market than there were years ago, so even if your model is not old or broken, it might be time to upgrade to something that will save more energy and be better for the planet.
Whether you are looking to purchase your first freezer, or are looking to replace an existing model, there are a number of factors from freezer type to space requirements and maintenance protocols that should be considered and discussed before a purchase is made. Once you combine the many factors with your budget, then you need to work out which model is best for you.
Because it can be time-consuming to work out how you should go about purchasing a new ULT Freezer, we have put together this article to go through some of the key questions that you should ask yourself when buying a new ULT freezer, to understand which ULT freezer is best for you, how you can get the most out of your new model, and how you can streamline your buying process.
What ULT Freezer Options Are Available to Me?
There are many different types of ULT freezers available to suit all budgets and needs. Some models might be cheaper, but they won’t offer as many features, whereas some models will come with extra features to keep the internal temperature more constant and safer from fluctuation, but might come at a more premium price.
ULT freezers come in two main types—chest and upright—and there are a number of popular options that are commonly chosen. One popular option is an ULT freezer that has vacuum insulated panel (VIP) insulation, which has more capacity within a small footprint and is a good option where floor space is limited. Another popular option is a twin ULT freezer with separate compressors, but the most popular option where performance is the key driver over cost is a ULT freezer that has two compressors.
When looking at the cost side of things, there are low-cost freezers on offer, but the lower costs eliminate some of the components, making them a riskier option if you need a stable and reliable performance.
For those who are not constrained by budgets and need better performance, there are various mid-range and high-end models that can be chosen from, so it’s always good to not only understand your budget but also the needs of the freezer for your lab. When you know this, you can make a more informed choice on the range of ULT freezers that are suitable.
Mid-range freezers will provide consistent -85°C temperatures and protect against oil logging, which is when the oil clogs in the capillary tubes, compromising the essential cascade system within the freezer, and raising the temperature of the freezer. Some mid-range freezers will also come with other features such as USB ports to plug in and manually download operation data, and VIP insulated freezers are also available in this price range.
Higher end freezers are available for those who need a certain level of quality control to validate their product or maintain histories. Higher end freezers provide better refrigeration and automated data logging that tracks the operations, events, temperatures, and alarms of the ULT freezer. The best ULT freezers available have a number of features that help to maintain the temperature and reduce frost build up.
Some of the key features that can be purchased with high-end freezers include claw latches for securing the inner freezer doors and tightening the hinge against the gasket, low wattage halo bypass heaters that help to keep gaskets around the outer door clean, and extra layers of insulation on the inner and outer doors to help maintain the temperature inside the freezer.
Is It the Right Time to Buy?
Knowing when it’s the right time is something that is personal to each lab manager but understanding if you need to upgrade for better energy efficiency, or if your existing model is getting old and dropping in performance, is key to understanding when you should buy a new freezer.
For example, if it’s taking hours for the freezer to get back up to temperature after closing the door, then it can be a sign of poor performance and an early indicator for impending compressor failure. If this is something that’s not fixable, then the freezer should be replaced before it breaks. There are a number of metrics, such as pull down and warm up time, that can be used to assess whether a freezer is running optimally (it should be 10 minutes to cool the freezer down after closing) and to determine if the unit needs replacing soon.
If it’s looking like there may be a chance of the unit performing poorly in the near future, and you have a lot of money’s worth of samples in the freezer, it might also be time to think about replacing the freezer before it breaks and spoils the samples. You could implement protocols in your lab that state that a freezer should be replaced in X number of years, so that this never becomes an issue, as it can be a lot more costly to replace spoiled samples than it is to buy a new freezer unit. If you’re also looking to upgrade to a more energy efficient unit, then it’s certainly the right time to buy as well, as freezers increase in energy consumption by around 3% each year of use, so a newer unit could bring about lower running costs.
Finally, another scenario that shows it’s the right time for you to buy is when the replacement costs for a freezer (when a component breaks) is a high percentage of the cost of a new freezer. For example, replacing a compressor could be as much as 50% the cost of a new freezer. The general rule of thumb is that if the repair and replacement is going to cost 25% or more of the cost to buy a new freezer, then it's more cost-effective to purchase a new freezer (especially if the freezer in question is old).
Where Will I Put It?
There are a number of factors that need to be considered when determining where you’re going to put a new freezer, and the space available could potentially limit which freezers you can buy. So, it’s good to know what your space requirements are, as well as how well suited any potential location is for containing a freezer.
For example, wherever you put the ULT freezer, the local temperature needs to be less than 90°F (32°C), otherwise it will be too hot for the freezer. Additionally, if you plan to place more than one ULT freezer in a room, then the ULTs will need space to ventilate. The recommended ventilation clearance is 8 inches (203 millimeters) above a ULT and 5 inches (127 millimeters) on the sides and back. If the options for placing a ULT cannot meet the environmental requirements in your lab, water-cooled condensers can be added to prevent them from overheating.
In addition to considering the local environmental factors for a freezer location, you also need to account for the size of the freezer itself. Aside from finding a space large enough, and appropriate enough, you need to ensure that the freezer will fit through all doorways to the lab. Most freezers are built to international standards of 90 cm (35 1/2”) wide and 2 m (78 3/4”) high. Given that larger freezers are more cost-effective than smaller freezers, you need to be able to work out what size will get through your facility, as this will help to determine the costs and cost effectiveness of your potential purchase.
Are There Any Facility Concerns I Should Be Aware of?
As well as finding the right location, you need to ensure that your facility is well equipped to handle an ULT freezer. ULT freezers need chilled process water, reliable power, and access to a vacuum, so you need to ask yourself if your chosen location will provide access to those for your freezer. If you’re looking to purchase a higher end freezer, you will also need to make sure that you have the right data ports to communicate logged data and/or some space for a backup battery.
You also need to understand your facility's power sources, as most are 208V-230V at 60 Hz, 15Amp single-phase circuits. If you are in a region where the voltage is lower, you may need to also look into adding a voltage booster as the freezer will not get up to temperature easily at lower voltages and it's more likely that the freezer will fail quickly. You also need to analyze whether you are in a region where power is not reliable, or if there are a lot of natural disasters, because it’s then worthwhile to look into adding backup kit options that provide alerts on power problems and maintain a set temperature for a short time.
What Are the Best Ways to Extend the Life of My ULT Freezer?
Even though this has more to do with protocols once you have your freezer, it's good to understand this area and ask yourself how you’re going to use your freezer, as it will provide you with insights into how long your freezer is likely to last and how cost-effective each option is going to be. You will also need to ask some questions to the researchers in the lab to make sure they are fully aware of how to best take care of your new freezer.
First off, you need to make sure that any researchers intend to use the ULT freezer properly, and not use it as a blast freezer. Additionally, you need to make sure that researchers are aware that warm samples shouldn’t be placed in the freezer, and while ULT freezers can accommodate some unfrozen samples, if you abuse the ULT, the compressor can break in only a few years.
Finally, there are a number of maintenance procedures that can help to keep the freezer clean and dust free. By employing preventative measures — such as cleaning the condenser filter and coil, cleaning the door gaskets, storing materials properly, defrosting the chamber, paying attention to freezer alarms, replacing the backup battery every 2.5 years, removing any frost build up, and monitoring the vacuum relief port — you can extend the lifetime of the freezer. So, you need to ask your researchers if they fully understand the maintenance requirements surrounding ULT freezers.
If you understand these factors beforehand and ask questions about how the freezer is going to be treated after purchase, then you will be able to get the maximum amount of lifetime out of your new freezer.