Hey Reader, how often do you defrost your freezer at home? And in the lab?
Whether it’s cleaning or sample organization, it often feels tedious.
But that’s only because most people lack a clear strategy.
Here’s a ready-to-use outline to help you tackle both efficiently.
Today's Lesson: Freezer Maintenance
Underestimated actions to keep freezers healthy
Number Of The Day
According to a study by Farley and colleagues, leaving your freezer door open for 60 seconds increases the internal temperature by up to 4.8°C on average. Although temperature variations occur between the top and bottom shelves, keeping your freezer at -70°C only results in a 1.2°C increase. Thus, sample organization is critical to minimize door openings (we all know the problem of thinking "the sample should be there").
4.8
Maintaning Freezers Sustainably
Although Proper freezer and sample maintenance can save a lot of energy, it also will:
A) Safeguard samples from being lost.
B) Prevent unnecessary failures and reduce search time.
C) Maintain freezer health, as frequent openings and insufficient cleaning are the main causes of failure.
Farley and colleagues showed that opening a freezer door for just 1 minute can lead to significant temperature drops. However, the stark variation in data comes from temperature differences from measuring bottom vs middle vs top shelf within the freezer. Of note, how severe the differences are depends on the model.
If your freezer fails, you have only a few hours before it reaches temperatures that could harm your samples. Therefore, prevention is key.
Sample Organization
Each time the door is opened, warm air enters, forcing the compressor restore lower temperatures. Additionally, this leads to ice buildup on the lid, increasing the risk of compressor overload due to constant warm air exposure.
However, a well-organized system comes with further advantages for your science:
1. Reduces time needed for searching samples.
2. Prevents samples from being lost or forgotten (consider the high turnover of people in laboratories).
3. Ensures detailed sample metadata, which, if missing, might lead to misleading results:
Experiment-specific notes (e.g., genetic variations in bacterial strains, passage number for cell cultures, source of biological material).
Treatment conditions (e.g., exposure to chemicals, storage buffer composition).
Tracking expiration dates to prevent unnecessary rework or contamination from degraded samples.
How to?
The simplest and cheapest approach is an Excel-based tracking system.
In short, you use one sheet to track each type of sample/reagent and one for each freezer.
While an Excel system is highly customizable and cost-effective, it requires manual updates and is prone to human error.
Otherwise, you can decide for an automated solution - using a sample management software and QR codes that are readable with with a smartphone.
These systems also enable enhanced data storage, including full experimental history and direct links to references or protocols.
Some software options even synchronize with electronic lab notebooks (ELNs) or provide real-time tracking of reagent usage
However, no matter how well-organized your freezer is, you will still have to open it. Each time you do, humid air enters.
How to Maintain & Clean Your Freezer
The most common cause of freezer failure is compressor overload, often due to blocked ventilation or insufficient heat transfer.
This is the filter you’ll find at the base or back of your freezer. Just like your computer slows down when the filter in front of the fan is full of dust, the freezer's compressor has to work harder to maintain low temperatures. Cleaning it with a vacuum or a gentle detergent is best. The picture is taken from the Eppendorf guide to freezer maintenance.
While the former is typically caused by dust accumulation on the filter, the latter is linked to dust on the condenser coils. Additionally, ice buildup on the gasket/rubber seal can prevent proper closure, forcing the freezer to run constantly to compensate for the air exchange.
The key steps to keeping your freezer in good condition are:
Cleaning the condenser filter (usually located at the base/back).
Cleaning the condenser coils.
Defrosting the freezer.
Cleaning the vacuum relief port/auto vent port.
Discarding unnecessary samples
A condenser in a freezer helps release heat absorbed from the inside of the freezer to the surrounding environment. It works by allowing the refrigerant, which has absorbed heat from inside the freezer, to release that heat as it changes from a gas back into a liquid. This process helps maintain low temperatures inside the freezer.
Also, this NIH video explains quite well how to clean the filters.
Applying The Knowledge
While these activities do not generate new data, they ensure your work runs efficiently and that samples remain well-preserved.
Interestingly, the studythat investigated how long it would take freezers to warm up after a power outage found that the difference between -80 and -70 is just 3 hours. PS: I thought I would go fancy with a Heat Map instead of yet another bar chart : )
Even if your lab members aren’t actively participating, I highly recommend setting up a sample organization system and basic freezer maintenance procedures for yourself. The benefits will become clear once you've worked on a project for more than six months.
If you receive positive feedback from your team, use that momentum:
Schedule routine cleaning in your lab’s maintenance calendar.
Ensure guides on freezer cleaning and sample documentation are easily accessible. Ideally, store them in the same folder as the actual software/Excel file.
Provide proper training for team members. If people feel uncertain, they might either avoid the task or do it half-heartedly, leading to mistakes.
Gumapas, L., Simons, G., 2012. Factors affecting the performance, energy consumption, and carbon footprint for ultra-low temperature freezers: Case study at the National Institutes of Health. World Review of Science, Technology and Sustainable Development, (), –. doi:10.1504/WRSTSD.2013.050786.
Studies:
Farley, M., McTeir, B., Arnott, A., Evans, A., 2015. Efficient ULT freezer storage: An investigation of ULT freezer energy and temperature dynamics. The University of Edinburgh
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Edited by Patrick Penndorf Connection@ReAdvance.com Lutherstraße 159, 07743, Jena, Thuringia, Germany Data Protection & Impressum If you think we do a bad job: Unsubscribe
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